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[MCQ] Computer Communication Networks

Exit Intent

Module 1

1. OSI stands for __________
a) open system interconnection
b) operating system interface
c) optical service implementation
d) open service Internet
Answer: a
Explanation: OSI is the abbreviation for Open System Interconnection. OSI model provides a structured plan on how applications communicate over a network, which also helps us to have a structured plan for troubleshooting. It is recognized by the ISO as the generalized model for computer network i.e. it can be modified to design any kind of computer network.

2. The number of layers in ISO OSI reference model is __________
a) 4
b) 5
c) 6
d) 7
Answer: d
Explanation: In OSI reference model, there are 7 layers namely Application, Presentation, Session, Transport, Network, Data Link and Physical layer. Each layer uses a protocol to perform its designated function, for example, the data link layer uses error detection protocols for error control functions.

3. TCP/IP model does not have ______ layer but OSI model have this layer.
a) session layer
b) transport layer
c) application layer
d) network layer
Answer: a
Explanation: In OSI reference model, there are two layers which are not present in TCP/IP model. They are Presentation and Session layer. The functions of Presentation and Session layer in the OSI model are handled by the transport layer itself in TCP/IP.

4. Which layer is used to link the network support layers and user support layers?
a) session layer
b) data link layer
c) transport layer
d) network layer
Answer: c
Explanation: Physical, data link and network layers are network support layers and session, presentation and application layers are user support layers. The transport layer links these layers by segmenting and rearranging the data. It uses protocols like TCP and UDP.

5. Which address is used on the internet for employing the TCP/IP protocols?
a) physical address and logical address
b) port address
c) specific address
d) all of the mentioned
Answer: d
Explanation: The physical, logical, port and specific addresses are used in TCP/IP protocol. All the addressing schemes, that is physical (MAC) and logical address, port address and specific address are employed in both TCP/IP model and OSI model. In TCP/IP, the addresses are more focused on the internet implementation of these addresses.

6. TCP/IP model was developed _____ the OSI model.
a) prior to
b) after
c) simultaneous to
d) with no link to
Answer: a
Explanation: Several TCP/IP prototypes were developed at multiple research centers between 1978 and 1983, whereas OSI reference model was developed in the year 1984. TCP/IP was developed with the intention to create a model for the Internet while OSI was intended to be a general network model.

7. Which layer is responsible for process to process delivery in a general network model?
a) network layer
b) transport layer
c) session layer
d) data link layer
Answer: b
Explanation: The role of Transport layer (Layer 4) is to establish a logical end to end connection between two systems in a network. The protocols used in Transport layer is TCP and UDP. The transport layer is responsible for segmentation of the data. It uses ports for the implementation of process-to-process delivery.

8. Which address is used to identify a process on a host by the transport layer?
a) physical address
b) logical address
c) port address
d) specific address
Answer: c
Explanation: A port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server. Some examples of port numbers are port 20 which is used for FTP data, port 22 which is used for SSH remote login ,and port 23 which is used for TELNET.

9. Which layer provides the services to user?
a) application layer
b) session layer
c) presentation layer
d) physical layer
Answer: a
Explanation: In networking, a user mainly interacts with application layer to create and send information to other computer or network. Application layer provides the interface between applications and the network. It is the top-most layer in both the TCP/IP and the OSI model.

10. Transmission data rate is decided by ____________
a) network layer
b) physical layer
c) data link layer
d) transport layer
Answer: b
Explanation: Physical layer is a layer 1 device which deals with network cables or the standards in use like connectors, pins, electric current used etc. Basically the transmission speed is determined by the cables and connectors used. Hence it is physical layer that determines the transmission speed in network. Some of the cables used for high speed data transmission are optical fiber cables and twisted pair cables.

11. How many layers are present in the Internet protocol stack (TCP/IP model)?
a) 5
b) 7
c) 6
d) 10
Answer: a
Explanation: There are five layers in the Internet Protocol stack. The five layers in Internet Protocol stack is Application, Transport, Network, Data link and Physical layer. The internet protocol stack model is also called the TCP/IP model and it’s used in modern Internet Communication.

12. The number of layers in ISO OSI reference model is __________
a) 5
b) 7
c) 6
d) 10
Answer: b
Explanation: The seven layers in ISO OSI reference model is Application, Presentation, Session, Transport, Network, Data link and Physical layer. OSI stands for Open System Interconnect and it is a generalized model.

13. Which of the following layers is an addition to OSI model when compared with TCP IP model?
a) Application layer
b) Presentation layer
c) Session layer
d) Session and Presentation layer
Answer: d
Explanation: The only difference between OSI model and TCP/IP model is that the functions of Presentation and Session layer in the OSI model are handled by the transport layer itself in TCP/IP. OSI is a generalized model and TCP/IP is an application specific model.

14. Application layer is implemented in ____________
a) End system
b) NIC
c) Ethernet
d) Packet transport
Answer: a
Explanation: Not only application layer, but presentation layer, session layer and transport layer are also implemented in the end system. The layers below are implemented outside the end system, for example, the network layer is implemented on the routers and the physical layer is implemented for the medium.

15. Transport layer is implemented in ______________
a) End system
b) NIC
c) Ethernet
d) Signal transmission
Answer: a
Explanation: Application, Presentation, Session and Transport layer are implemented in the end system. The transport layer handles the process to process delivery of the packet through ports.

16. The functionalities of the presentation layer include ____________
a) Data compression
b) Data encryption
c) Data description
d) All of the mentioned
Answer: d
Explanation: Some functions of the presentation layer include character-code translation, data conversion, data encryption and decryption, and data translation. It connects the application layer with the layers below converting the human readable text and media to machine readable format and vice-versa.

17. Delimiting and synchronization of data exchange is provided by __________
a) Application layer
b) Session layer
c) Transport layer
d) Link layer
Answer: b
Explanation: The session layer provides the mechanism for opening, closing and managing a session between end-user application processes. The session layer 5 is responsible for establishing managing synchronizing and terminating sessions. In TCP/IP protocol stack, the functions of the session layer are handled by the transport layer itself and thus the session layer is missing from the TCP/IP model.

18. In OSI model, when data is sent from device A to device B, the 5th layer to receive data at B is _________
a) Application layer
b) Transport layer
c) Link layer
d) Session layer
Answer: d
Explanation: In OSI reference model, the fifth layer is Session layer. Session layer provides the mechanism for opening, closing and managing a session between end-user application processes. In TCP/IP protocol stack, the functions of the session layer are handled by the transport layer itself and thus the session layer is missing from the TCP/IP model.

19. In TCP IP Model, when data is sent from device A to device B, the 5th layer to receive data at B is ____________
a) Application layer
b) Transport layer
c) Link layer
d) Session layer
Answer: a
Explanation: In TCP/IP model, the fifth layer is application layer. When data is sent from device A to device B, the 5th layer to receive data at B is application layer. Application layer provides the interface between applications and the network. The user interacts with only this layer.

20. In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______
a) Added
b) Removed
c) Rearranged
d) Randomized
Answer: b
Explanation: In OSI reference model, when data packet moves from lower layers to higher layer, headers get removed. Whereas when the data packet moves from higher layer to lower layers, headers are added. These headers contain the essential control information for the protocols used on the specific layer.

21. The acronym OSI stands for ____ in computer networking.
A) Organization for Standards Institute
B) Open Systems Interconnection
C) Organizing Systems Interconnection
D) Open Systems Interworking
answer: B
Explanation:OSI refers to Open Systems for Interconnection.

22. Who developed standards for the OSI reference model?
A) ANSI – American National Standards Institute
B) ISO – International Standards Organization
C) IEEE – Institute of Electrical and Electronics Engineers
D) ACM – Association for Computing Machinery
answer:  B
Explanation:Yes. It is ISO (International Standards Organization) that developed standards for operating OSI model layers in the year 1984.

23. How many layers are there in the OSI reference model of networking?
A) 5
B) 6
C) 7
D) 8
answer:  C
Explanation: 7 Layers in total.

24. Each layer of the OSI model receives services or data from a ___ layer.
A) below layer
B) above layer
C) –
D) –
answer: A
Explanation: Layers receive data or services from the below layers.

2.5 In the OSI model, each layer gives services or data to the __ layer.
A) below
B) above
C) –
D) –
answer: B
Explanation: In other words, the upper layers always receive services or data from the below layers.

26. A layer of the OSI model on one system communicates with the ___ layer of its peer system.
A) above
B) below
C) same
D) None
answer: C
Explanation: So, any given OSI layer can communicate with the same layer of its peer node.

27. Choose the correct layer numbers and names of the OSI model below.
A) Layer 7 – Application Layer, Layer 6 – Presentation Layer
B) Layer 5 – Session Layer, Layer 4 – Transport Layer
C) Layer 3 – Network Layer, Layer 2 – Data Link Layer, Layer 1 – Physical Layer
D) All the above.
answer:  D
Explanation: The matching order is as follows. Layer 7 = Application Layer, Layer 6 = Presentation Layer, Layer 5 = Session Layer, Layer 4 = Transport Layer, Layer 3 = Network Layer, Layer 2 = Data Link Layer, Layer 1 = Physical Layer.

28 In an OSI model, the lowest layer is the ___ layer.
A) Application Layer
B) Physical Layer
C) Presentation Layer
D) Data Link Layer
answer:  B
Explanation:Yes, the Physical layer is the lowest.

29 In the OSI model, which is the highest layer?
A) Application Layer
B) Physical Layer
C) Presentation Layer
D) Network Layer
answer: A
Explanation:Yes, the Application Layer or Layer-7 is the highest layer.

30 In the OSI model, the bottom 3 layers assist in ___.
A) converting data
B) transporting data
C) –
D) –
answer: B
Explanation:
It is because of the bottom 3 layers of OSI, the data gets transferred from one node to another through the network.

31. What are the advantages of 7 layers of OSI model?
A) Troubleshooting the network is easy.
B) Developing new functions or services for a particular layer is easy.
C) Developing hardware devices targetting certain layers is easy because the services to be offered are fixed.
D) All the above
answer: D

32 A set of standards that define how to communicate with each layer of the OSI model are ___.
A) functions
B) protocols
C) data formats
D) All the above.
answer: D

33 The layer that transmits data in the form of bit streams using electrical and mechanical systems is ___ in the OSI model.
A) Physical layer
B) Data Link Layer
C) Network Layer
D) Transport Layer
answer: A
Explanation: Physical Layer

34 The physical layer involves ___
A) Optical, electrical and mechanical properties
B) Voltage levels, timing and frequency
C) Physical connections
D) All the above
answer: D

35 The transmission media like ___ are part of the Physical layer of OSI model.
A) Copper cables
B) OFC – Optical Fiber Cables
C) RF – Radio Frequency waves including Microwaves
D) All the above
answer: D

36 An ethernet cable is part of __ layer in the OSI model.
A) Physical layer
B) Data Link Layer
C) Network Layer
D) Transport Layer
answer: A

37 The protocols working in the physical layer of the OSI Model are ___.
A) USB, Bluetooth, IEEE 802.3, IEEE 802.11, IEEE 802.15, IEEE 802.16
B) POTS, PDH, SONET, SDH, PON, OTN, DSL, ITU-T V series, ITU-T G.hn PHY
C) I.430, I.431, EIA/TIA-232, EIA/TIA-449
D) All the above
answer: D
Explanation:
All the above protocols are worth remembering for competitive exams.

38 Which is the layer of the OSI reference model that employs Error Detection?
A) Physical Layer
B) Data Link Layer
C) Network Layer
D) Session Layer
answer: B
Explanation: Data Link Layer

39 Which is the layer that converts Packets to Frames and Frames to Packets in the OSI model?
A) Physical Layer
B) Data Link Layer
C) Network Layer
D) Transport Layer
answer: C
Explanation: Network Layer

40 Which is the layer that converts Raw Bits to Frames and Frames to Raw Bits in the OSI model?
A) Physical Layer
B) Data Link Layer
C) Network Layer
D) Transport Layer
answer: B
Explanation:Data Link Layer

41. Which methods are commonly used in Server Socket class?
a) Public Output Stream get Output Stream ()
b) Public Socket accept ()
c) Public synchronized void close ()
d) Public void connect ()
Answer: b
Explanation: The Public socket accept () method is used by the ServerSocket class to accept the connection request of exactly one client at a time. The client requests by initializing the socket object with the servers IP address.

42. Which constructor of Datagram Socket class is used to create a datagram socket and binds it with the given Port Number?
a) Datagram Socket(int port)
b) Datagram Socket(int port, Int Address address)
c) Datagram Socket()
d) Datagram Socket(int address)
Answer: b
Explanation: Datagram Socket (int port, Int Address address) is used to create a datagram socket. A datagram socket is created for connection-less communication between the server and the client. There is no accept() method in this class.

43. The client in socket programming must know which information?
a) IP address of Server
b) Port number
c) Both IP address of Server & Port number
d) Only its own IP address
Answer: c
Explanation: The client in socket programming must know IP address of Server as it has to use that IP address in order to initialize the socket class constructor. That is how the client requests a connection to the server.

44. The URL Connection class can be used to read and write data to the specified resource that is referred by the URL.
a) True
b) False
Answer: a
Explanation: The URL Connection class can be used to read and write data to the specified resource referred by the URL. A connection to the URL is initialized by the OpenConnection() method of the class.

45. Datagram is basically just a piece of information but there is no guarantee of its content, arrival or arrival time.
a) True
b) False
Answer: a
Explanation: Datagram is basically some information travelling between the sender and the receiver, but there is no guarantee of its content, arrival or arrival time. A Datagram socket class object is created to make a datagram connection between the server and the client.

46. TCP, FTP, Telnet, SMTP, POP etc. are examples of ___________
a) Socket
b) IP Address
c) Protocol
d) MAC Address
Answer: c
Explanation: TCP, FTP, Telnet, SMTP, POP etc. are examples of Protocol. Out of them, TCP is a transport layer protocol and FTP, TELNET, SMTP and POP are application layer protocols.

47. What does the java.net.InetAddress class represent?
a) Socket
b) IP Address
c) Protocol
d) MAC Address
Answer: b
Explanation: The java.net.InetAddress class represents IP Address of a particular specified host. It can be used to resolve the host name from the IP address or the IP address from the host name.

48. The flush () method of Print Stream class flushes any un-cleared buffers in the memory.
a) True
b) False
Answer: a
Explanation: The flush () method of Print Stream class flushes any un cleared buffers in memory.

49. Which classes are used for connection-less socket programming?
a) Datagram Socket
b) Datagram Packet
c) Both Datagram Socket & Datagram Packet
d) Server Socket
Answer: c
Explanation: Datagram is basically some information travelling between the sender and the receiver, but there is no guarantee of its content, arrival or arrival time. Datagram Socket, Datagram Packet are used for connection-less socket programming, while Server Socket is used for connection-oriented socket programming.

50. In Inet Address class, which method returns the host name of the IP Address?
a) Public String get Hostname()
b) Public String getHostAddress()
c) Public static InetAddress get Localhost()
d) Public getByName()
Answer: a
Explanation: In Inet Address class public String getHostname() method returns the host name of the IP Address. The getHostAddress() method returns the IP address of the given host name.

51.In the OSI model, as a data packet moves from the lower to the upper layers, headers are _______
A.) Added
B.) Rearranged
C.) Removed
D.) None of these
Answer: ‘C’

52.The number of layers in ISO OSI reference model
A.) 5
B.) 7
C.) 6
D.) 8
Answer:  ‘B’

53.In Internet protocol stack, when data is sent from device A to device B, the 5th layer to receive data at B is
A.) Application layer
B.) Transport layer
C.) Link layer
D.) Session layer
Answer:  ‘A’

54.Which address is used in an internet employing the TCP/IP protocols?
A.) physical address and logical address
B.) port address
C.) specific address
D.) all of these
Answer: Option ‘D’

5.TCP/IP model does not have ______ layer but OSI model have this layer.
A.) session layer
B.) presentation layer
C.) application layer
D.) both (a) and (b)
Answer: Option ‘D’

56.The functionalities of presentation layer includes
A.) Data compression
B.) Data encryption
C.) Data description
D.) All of these
Answer: Option ‘D’

57.Transmission data rate is decided by
A.) network layer
B.) physical layer
C.) data link layer
D.) transport layer
Answer: Option ‘B’

58.This layer in an addition to OSI model
A.) Application layer
B.) Presentation layer
C.) Session layer
D.) Both b and c
Answer: Option ‘D’

59.OSI stands for
A.) open system interconnection
B.) operating system interface
C.) the optical service implementation
D.) none of these
Answer: Option ‘A’

60.The number of layers in ISO OSI reference model
A.) 5
B.) 7
C.) 6
D.) 8
Answer: Option ‘B’

61. When collection of various computers seems a single coherent system to its client, then it is called _________
a) computer network
b) distributed system
c) networking system
d) mail system
Answer: b
Explanation: A Computer network is defined as a collection of interconnected computers which uses a single technology for connection.
A distributed system is also the same as computer network but the main difference is that the whole collection of computers appears to its users as a single coherent system.
Example:- World wide web

62. Two devices are in network if __________
a) a process in one device is able to exchange information with a process in another device
b) a process is running on both devices
c) PIDs of the processes running of different devices are same
d) a process is active and another is inactive
Answer: a
Explanation: A computer network, or data network, is a digital telecommunications network which allows nodes to share resources. In computer networks, computing devices exchange data with each other using connections between nodes. The nodes have certain processes which enable them to share a specific type of data using a distinct protocol.

63. Which of the following computer networks is built on the top of another network?
a) prior network
b) chief network
c) prime network
d) overlay network
Answer: d
Explanation: An overlay network is a computer network that is built on top of another network. Some examples of an overlay network are Virtual Private Networks (VPN) and Peer-to-Peer Networks (P2P).

64. In computer network nodes are _________
a) the computer that originates the data
b) the computer that routes the data
c) the computer that terminates the data
d) all of the mentioned
Answer: d
Explanation: In a computer network, a node can be anything that is capable of sending data or receiving data or even routing the data to its destination. Routers, Computers and Smartphones are some examples of network nodes.

65. Communication channel is shared by all the machines on the network in ________
a) broadcast network
b) unicast network
c) multicast network
d) anycast network
Answer: a
Explanation: In a broadcast network, information is sent to all stations in a network whereas in a multicast network the data or information is sent to a group of stations in the network. In unicast network, information is sent to only one specific station. The broadcast address of the network is the last assigned address of the network.

66. Bluetooth is an example of __________
a) personal area network
b) local area network
c) virtual private network
d) wide area network
Answer: a
Explanation: Bluetooth is a wireless technology used to create a wireless personal area network for data transfer up to a distance of 10 meters. It operates on 2.45 GHz frequency band for transmission.

67. A __________ is a device that forwards packets between networks by processing the routing information included in the packet.
a) bridge
b) firewall
c) router
d) hub
Answer: c
Explanation: A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. They make use of routing protocols like RIP to find the cheapest path to the destination.

68. A list of protocols used by a system, one protocol per layer, is called ________
a) protocol architecture
b) protocol stack
c) protocol suite
d) protocol system
Answer: b
Explanation: A protocol stack refers to a group of protocols that are running concurrently that are employed for the implementation of network protocol suite. Each layer in the network model has to use one specific protocol from the protocol stack.

69. Network congestion occurs _________
a) in case of traffic overloading
b) when a system terminates
c) when connection between two nodes terminates
d) in case of transfer failure
Answer: a
Explanation: Network congestion occurs when traffic in the network is more than the network could handle. To avoid network congestion, the network management uses various open-loop and closed-loop congestion control techniques.

70. Which of the following networks extends a private network across public networks?
a) local area network
b) virtual private network
c) enterprise private network
d) storage area network
Answer: b
Explanation: A virtual private network extends a private network across a public network, and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network.VPN provides enhanced security and online anonymity to users on the internet. It is also used to unblock websites which are unavailable in certain regions.

Module 02

1. The physical layer is concerned with ___________
a) bit-by-bit delivery
p) process to process delivery
c) application to application delivery
d) port to port delivery
Answer: a
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.

2. Which transmission media provides the highest transmission speed in a network?
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable
Answer: c
Explanation: Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.

3. Bits can be sent over guided and unguided media as analog signal by ___________
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation
Answer: a
Explanation: In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.

4. The portion of physical layer that interfaces with the media access control sublayer is called ___________
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) physical transport sublayer
Answer: a
Explanation: The portion of physical layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions. It handles which media connection the signal should be forwarded to physically.

5. The physical layer provides __________
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned
Answer: d
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1). Physical layer deals with bit to bit delivery of the data aided by the various transmission mediums.

6. In asynchronous serial communication the physical layer provides ___________
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) only start signalling
Answer: c
Explanation: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed. Unlike asynchronous serial communication, in synchronous serial communication a clock signal is used for communication, so the start and stop method is not really required.

7. The physical layer is responsible for __________
a) line coding
b) channel coding
c) modulation
d) all of the mentioned
Answer: d
Explanation: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information. The physical configuration including pins, connectors and the electric current used is dealt in the physical layer based on the requirement of the network application.

8. The physical layer translates logical communication requests from the ______ into hardware specific operations.
a) data link layer
b) network layer
c) trasnport layer
d) application layer
Answer: a
Explanation: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables. Some examples of the cables used are optical fiber cables, twisted pair cables and co-axial cables.

9. A single channel is shared by multiple signals by ____________
a) analog modulation
b) digital modulation
c) multiplexing
d) phase modulation
Answer: c
Explanation: In communication and computer networks, the main goal is to share a scarce resource. This is done by multiplexing, where multiple analog or digital signals are combined into one signal over a shared medium. The multiple kinds of signals are designated by the transport layer which is the layer present on a higher level than the physical layer.

10. Wireless transmission of signals can be done via ___________
a) radio waves
b) microwaves
c) infrared
d) all of the mentioned
Answer: d
Explanation: Wireless transmission is carried out by radio waves, microwaves and IR waves. These waves range from 3 Khz to above 300 Ghz and are more suitable for wireless transmission. Radio waves can penetrate through walls and are used in radio communications, microwaves and infrared (IR) waves cannot penetrate through walls and are used for satellite communications and device communications respectively.

11. Physical or logical arrangement of network is __________
a) Topology
b) Routing
c) Networking
d) Control
Answer: a
Explanation: Topology in networks is the structure or pattern in which each and every node in the network is connected. There are many topologies in networking like bus, tree, ring, star, mesh, and hybrid topology. There is no particular best topology and a suitable topology can be chosen based on the kind of application of the network .

12. Which network topology requires a central controller or hub?
a) Star
b) Mesh
c) Ring
d) Bus
Answer: a
Explanation: In star topology, no computer is connected to another computer directly but all the computers are connected to a central hub. Every message sent from a source computer goes through the hub and the hub then forwards the message only to the intended destination computer.

13. _______ topology requires a multipoint connection.
a) Star
b) Mesh
c) Ring
d) Bus
Answer: d
Explanation: In bus topology, there is a single cable to which all the network nodes are connected. So whenever a node tries to send a message or data to other nodes, this data passes through all other nodes in the network through the cable. It is really simple to install but it’s not secure enough to be used in most of the computer network applications.

4. Data communication system spanning states, countries, or the whole world is ________
a) LAN
b) WAN
c) MAN
d) PAN
Answer: b
Explanation: WAN is the abbreviation for Wide Area Network. This network extends over a large geographical area. WANs are used to connect cities, states or even countries. A wireless connection is required to build a WAN. The best example of WAN is the Internet.

15. Data communication system within a building or campus is________
a) LAN
b) WAN
c) MAN
d) PAN
Answer: a
Explanation: LAN is an abbreviation for Local Area Network. This network interconnects computers in a small area such as schools, offices, residence etc. It is the most versatile kind of data communication system where most of the computer network concepts can be visibly used.

16. WAN stands for __________
a) World area network
b) Wide area network
c) Web area network
d) Web access network
Answer: b
Explanation: WAN is the abbreviation for Wide Area Network. This network extends over a large geographical area. These are used to connect cities, states or even countries. They can be connected through leased lines or satellites.

17. In TDM, slots are further divided into __________
a) Seconds
b) Frames
c) Packets
d) Bits
Answer: b
Explanation: TDM is the abbreviation for Time division multiplexing. It is technique for combining several low rate channels to a single high rate channel. For a certain time slot, the several channels could use the maximum bandwidth. Each channel is inactive for a period of time too. Some other multiplexing techniques are Frequency division multiplexing and Phase division multiplexing.

18. _____ is the multiplexing technique that shifts each signal to a different carrier frequency.
a) FDM
b) TDM
c) Both FDM & TDM
d) PDM
Answer: a
Explanation: FDM is an abbreviation for Frequency Division Multiplexing. This technique is used when the bandwidth of the channel is greater than the combined bandwidth of all the signals which are to be transmitted. The channel is active at all times unless a collision occurs with another channel trying to use the same frequency. Some other multiplexing techniques are Time division multiplexing and Phase division multiplexing.

19. The sharing of a medium and its link by two or more devices is called _________
a) Fully duplexing
b) Multiplexing
c) Micropleixng
d) Duplexing
Answer: b
Explanation: Multiplexing is a method using which one can send multiples signals through a shared medium at the same time. This helps in using less resources and thus saving the cost of sending messages.

20. Multiplexing is used in _______
a) Packet switching
b) Circuit switching
c) Data switching
d) Packet & Circuit switching
Answer: b
Explanation: Circuit switching is a switching method by which one can obtain a physical path between end points. Circuit switching method is also called a connection oriented network. Two nodes must be physically and logically connected to each other to create a circuit switching network.

21. Which multiplexing technique used to transmit digital signals?
a) FDM
b) TDM
c) WDM
d) FDM & WDM
Answer: b
Explanation: TDM abbreviation for Time Division Multiplexing is a method used for digital signals. Whereas FDM and WDM abbreviation for Frequency Division Multiplexing, and Wavelength Division Multiplexing, are used for analog signals. TDM is used in applications like ISDN (Integrated Services Digital Network) and PSTN (Public Switched Telephone Network).

22. If there are n signal sources of same data rate, then the TDM link has _______ slots.
a) n
b) n/2
c) n*2
d) 2n
Answer: a
Explanation: In TDM, the total unit of time is divided equally among all the signal sources and each and every source has access to the complete channel bandwidth during its allotted time slot. When the time slot of the source is not active, it remains idle and waits for its slot to begin.

23. If link transmits 4000frames per second, and each slot has 8 bits, the transmission rate of circuit this TDM is _________
a) 32kbps
b) 500bps
c) 500kbps
d) 32bps
Answer: a
Explanation: Transmission rate= frame rate * number of bits in a slot.
Given: Frame rate = 4000/sec and number of bits in slot = 8
Thus, Transmission rate = (4000 * 8) bps
= 32000bps
= 32kbps

24. The state when dedicated signals are idle are called __________
a) Death period
b) Poison period
c) Silent period
d) Stop period
Answer: c
Explanation: There are instances when connection between two endpoints has been established, but no communication or transfer of messages occurs. This period of time is called silent period. The silent period ends when either of the two endpoints starts the communication.

25. Multiplexing provides _________
a) Efficiency
b) Privacy
c) Anti jamming
d) Both Efficiency & Privacy
Answer: d
Explanation: Multiplexing helps us to transfer our messages over a shared channel. This brings up the issue of privacy and efficiency. Fortunately, Multiplexing has high efficiency and high privacy when implemented because in the implementation, the transport layer of the OSI network model handles the function of multiplexing through interfaces called ports which provide the required efficiency and privacy.

27. In TDM, the transmission rate of a multiplexed path is always _______ the sum of the transmission rates of the signal sources.
a) Greater than
b) Lesser than
c) Equal to
d) Equal to or greater than
Answer: a
Explanation: In TDM the transmission rate provided by the path that is multiplexed will always be greater than the sum of transmission rates of the single sources. This happens because the transmission rate is provided to each source only for a small period of time.

28. In TDM, slots are further divided into _________
a) Seconds
b) Frames
c) Packets
d) Bits
Answer: b
Explanation: TDM is the abbreviation for Time division multiplexing. It is technique for combining several low rate channels to a single high rate channel. For a certain time slot, the several channels could use the maximum bandwidth. Each channel is inactive for a period of time too. Some other multiplexing techniques are Frequency division multiplexing and Phase division multiplexing.

29. Which of this is not a guided media?
a) Fiber optical cable
b) Coaxial cable
c) Wireless LAN
d) Copper wire
Answer: c
Explanation: Wireless LAN is unguided media.

30. UTP is commonly used in __________
a) DSL
b) FTTP
c) HTTP
d) None of the mentioned
Answer: a
Explanation: Unshielded twisted pair(UTP) is commonly used in home access.

31. Coaxial cable consists of _______ concentric copper conductors.
a) 1
b) 2
c) 3
d) 4
Answer: b
Explanation: Coaxial cable has an inner conductor surrounded by a insulating layer, which is surrounded by a conducting shield. Coaxial cable is used to carry high frequency signals with low losses.

32. Fiber optics posses following properties __________
a) Immune electromagnetic interference
b) Very less signal attenuation
c) Very hard to tap
d) All of the mentioned
Answer: d
Explanation: In fibre optics the transmission of information is in the form of light or photons. Due to all above properties mentioned in options fibre optics can be submerged in water and are used at more risk environments.

33. If an Optical Carrier is represented as OC-n, generally the link speed equals(in Mbps) __________
a) n*39.8
b) n*51.8
c) 2n*51.8
d) None of the mentioned
Answer: b
Explanation: The base unit of transmission rates in optical fibre is 51.8 Mbits/s. So an optical carrier represented as OC-n has n*51.8 Mbits/s transmission speed. For eg. OC-3 has 3*51.8 Mbits/s speed.

34. Terrestrial radio channels are broadly classifed into _____ groups.
a) 2
b) 3
c) 4
d) 1
Answer: b
Explanation: The three types are those that operate over very short distance, those that operate in local areas, those that operate in the wide area.

35. Radio channels are attractive medium because __________
a) Can penetrate walls
b) Connectivity can be given to mobile user
c) Can carry signals for long distance
d) All of the mentioned
Answer: d
Explanation: Radio channels can penetrate walls, can be used to provide connectivity to mobile users and can also carry signals for long distances.

36. Geostationary satellites ___________
a) Are placed at a fixed point above the earth
b) Rotate the earth about a fixed axis
c) Rotate the earth about a varying axis
d) All of the mentioned
Answer: a
Explanation: They are placed in orbit at 36,000km above Earth’s surface.

371 _____________ allows LAN users to share computer programs and data.
a) Communication server
b) Print server
c) File server
d) Network
Answer: c
Explanation: A file server allows LAN users to share computer programs and data. It uses the File Transfer Protocol to provide this feature on ports 20 and 21. The file server works as a medium for the transfer.

38. With respect to physical media, STP cables stands for _________
a) Shielded Twisted Pair Cable
b) Spanning Tree Protocol Cable
c) Static Transport Protocol Cable
d) Shielded Two Power Cable
Answer: a
Explanation: For physical media, STP cable stands for Shielded twisted pair cable. 100 Mbps is the max data capacity of STP cable and its default connector is RJ45. It is popularly used in LANs due to its ease of maintenance and installation.

39. A standalone program that has been modified to work on a LAN by including concurrency controls such as file and record locking is an example of ___________
a) LAN intrinsic software
b) LAN aware software
c) Groupware
d) LAN ignorant software
Answer: a
Explanation: A standalone program that has been modified to work on a LAN by including concurrency controls such as file and record locking is an example of LAN intrinsic software. They are used to give better functionality of the program and the applications working over it to the users of the LAN.

40. The __________ portion of LAN management software restricts access, records user activities and audit data, etc.
a) Configuration management
b) Security management
c) Performance management
d) Recovery management
Answer: b
Explanation: The Security management portion of LAN management software restricts access, records user activities, and audit data. It is responsible for controlling access to the network based on predefined policy. The security management ensures authentication, confidentiality, and integrity in the LAN.

41. What is the max length of the Shielded twisted pair cable?
a) 100 ft
b) 200 ft
c) 100 m
d) 200 m
Answer: c
Explanation: The max the Shielded twisted pair cable is 100 meters. If the length exceeds 100 meters, the loss of signals flowing through the cable would be really high. Thus, STP cable is more suitable for smaller networks like LANs.

42. What is the max data transfer rate of STP cables?
a) 10 Mbps
b) 100 Mbps
c) 1000 Mbps
d) 10000 Mbps
Answer: b
Explanation: 100 Mbps is the max data transfer rate that can be handled by STP cables, and its default connector is RJ-45. 100 Mbps is a feasible data transfer rate for small networks like LANs.

43. Which connector does the STP cable use?
a) BNC
b) RJ-11
c) RJ-45
d) RJ-69
Answer: c
Explanation: RJ-45 is used for STP cable. 100 Mbps is the max data transfer rate that can be handled by STP. RJ-45 is popularly used to connect to modern-day routers, computer network cards, and other network devices.

44. What is the central device in star topology?
a) STP server
b) Hub/switch
c) PDC
d) Router
Answer: b
Explanation: In star topology, no computer is connected to another computer directly but all the computers are connected to a central switch or hub. Every message sent from a source computer goes through the switch or hub and the switch or hub then forwards the message only to the intended destination computer.

45. What is the max data transfer rate for optical fiber cable?
a) 10 Mbps
b) 100 Mbps
c) 1000 Mbps
d) 10000 Mbps
Answer: d
Explanation: Fiber channel speeds have been increasing over the years. 10000 Mbps is the max data transfer rate for optical fiber cables. It is said to be the fastest among the other kinds of cables like STP cables and co-axial cables. People are now using optical fiber cables instead of STP cables for LANs due to their fast data transfer capability.

46. Which of the following architecture uses the CSMA/CD access method?
a) ARC net
b) Ethernet
c) Router
d) STP server
Answer: b
Explanation: Collision detection is not possible in Ethernet without extensions. Collision detection techniques for multiple access like CSMA/CD are used to detect collisions in the Ethernet architecture.

Module 03

1.In _____ coding, we divide our message into blocks, each of k bits, called ___.
a.block; blockwords
b.linear; datawords
c.block; datawords
d.none of the above
answer: C. block; datawords

2. We add r redundant bits to each block to make the length n = k + r. The resulting n-bit blocks are called _________
a.datawords
b.blockwords
c.codewords
c.none of the above
answer: C. codewords

3. The ________ between two words is the number of differences between corresponding bits
a. Hamming code
b. Hamming distance
d. Hamming rule
d. none of the above
answer: B. Hamming distance

4. To guarantee the detection of up to 5 errors in all cases, the minimum Hamming distance in a block code must be _______
a. 5
b. 6
c. 11
d. none of the above
answer: B. 6

5. To guarantee correction of up to 5 errors in all cases, the minimum Hamming distance in a block code must be ________
a. 5
b. 6
c. 11
d. none of the above
answer: C. 11

6. In a linear block code, the _______ of any two valid codewords creates another valid codeword
a. XORing
b. ORing
c. ANDing
d. none of the above
answer: A. XORing

7. A simple parity-check code can detect __________ errors
* an even-number of
* two
* no errors
* an odd-number of
answer: D. an odd-number of

8. _______codes are special linear block codes with one extra property. If a codeword is rotated, the result is another codeword
a. Non-linear
b. Convolution
c. Cyclic
d. none of the above
answer: C. Cyclic

9. The _____of errors is more difficult than the ______
a. correction; detection
b. detection; correction
c. creation; correction
d. creation; detection
answer: A. correction; detection

10. In modulo-11 arithmetic, we use only the integers in the range ______, inclusive
a. 1 to 10
b. 1 to 11
c. 0 to 10
d. none of the above
answer: C. 0 to 10

11. In modulo-2 arithmetic, we use only ______
a. 1 and 2
b. 0 and 2
c. 0 and 1
d. none of the above
answer: C. 0 and 1

12. Adding 1 and 1 in modulo-2 arithmetic results in _________
a. 1
b. 2
c. 0
d. none of the above
answer: C. 0

13. In block coding, if k =2 and n =3, we have _______ invalid codewords
a. 8
b. 4
c. 2
d. none of the above
answer: B. 4

14. The Hamming distance between equal codewords is _________
a. 1
b. n
c. 0
d. none of the above
answer: C. 0

15. The Hamming distance between 100 and 001 is ________
a. 2
b. 0
c. 1
d. none of the above
answer: A. 2

16. In block coding, if n = 5, the maximum Hamming distance between two codewords is ________
a. 2
b. 3
c. 5
d. none of the above
C. 5

17. If the Hamming distance between a dataword and the corresponding codeword is three, there are _____ bits in error.
a. 3
b. 4
c. 5
d. none of the above
answer: A. 3

18. The _______ of a polynomial is the highest power in the polynomial
a. range
b. degree
c. power
d. none of the above
B. degree

19. The divisor in a cyclic code is normally called the _________
a. degree
b. generator
c. redundancy
d. none of the above
answer: B. generator

20. A generator that contains a factor of ____ can detect all odd-numbered errors.
a. x
b. x + 1
c. 1
d. none of the above
answer: B. x + 1

21. In layering, n layers provide service to
a) n layer
b) n-1 layer
c) n+1 layer
d) none of the mentioned
Answer: c
Explanation: In layering n layer provides service to n+1 layer and use the service provided by n-1 layer.

22. Which can be used as an intermediate device in between transmitter entity and receiver entity?
a) IP router
b) Microwave router
c) Telephone switch
d) All of the mentioned
Answer: d
Explanation: IP router, microwave router and telephone switch can be used as an intermediate device between communication of two entities.

23. Which has comparatively high frequency component?
a) Sine wave
b) Cosine wave
c) Square wave
d) None of the mentioned
Answer: c
Explanation: Square wave has comparatively high frequency component in them.

24. Which has continuous transmission?
a) Asynchronous
b) Synchronous
c) Asynchronous & Synchronous
d) None of the mentioned
Answer: b
Explanation: Synchronous has continuous transmission where as asynchronous have sporadic transmission.

25. Which requires bit transitions?
a) Asynchronous
b) Synchronous
c) Asynchronous & Synchronous
d) None of the mentioned
Answer: b
Explanation: Synchronous transmission needs bit transition.

6. In synchronous transmission, receiver must stay synchronous for
a) 4 bits
b) 8 bits
c) 9 bits
d) 16 bits
Answer: c
Explanation: In synchronous transmission, receiver must stay synchronous for 9 bits.

27. How error detection and correction is done?
a) By passing it through equalizer
b) By passing it through filter
c) By amplifying it
d) By adding redundancy bits
Answer: d
Explanation: Error can be detected and corrected by adding additional information that is by adding redundancy bits.

28. Which is more efficient?
a) Parity check
b) Cyclic redundancy check
c) Parity & Cyclic redundancy check
d) None of the mentioned
Answer: b
Explanation: Cyclic redundancy check is more efficient than parity check.

29. Which can detect two bit errors?
a) Parity check
b) Cyclic redundancy check
c) Parity & Cyclic redundancy check
d) None of the mentioned
Answer: b
Explanation: CRC is more powerful and it can detect various kind of errors like 2 bit errors.

30. CRC uses
a) Multiplication
b) Binary division
c) Multiplication & Binary division
d) None of the mentioned
Answer: c
Explanation: CRC uses more math like multiplication and binary division.

31. Control information in a system using _______ protocol can be just one or a multiple number of bits
a. an asynchronous
b. a character-oriented
c. a bit-oriented
d. b and c
answer: C. a bit-oriented

32. _______ is the basis for all bit-oriented protocols in use today
a. SDLC
b. HDLC
c. PPP
d. LAP
answer: B. HDLC

33. AN HDLC _______ station sends commands.
a. primary
b. secondary
c. combined
d. a and c
D. a and c

34. AN HDLC _______ station sends responses
a. primary
b. secondary
c. combined
d. b and c
answer: D. b and c

35. AN HDLC _______ station sends both commands and responses
a. primary
b. secondary
c. combined
d. none of the above
answer: C. combined

36. In a _______ configuration, an HDLC primary station and several secondary stations are connected
a. an unbalanced
b. a symmetrical
c. a balanced
d. an asymmetrical
answer: A. an unbalanced

37. In an HDLC _______ configuration, the connected stations each consist of two logical stations (primary and secondary)
a. unbalanced
b. symmetrical
c. balanced
d. asymmetrical
B. symmetrical

38. In an HDLC _______ configuration, both stations are of the combined type.
a. unbalanced
b. symmetrical
c. balanced
d. asymmetrical
answer: C. balanced

39. In an HDLC _______ configuration, a physical station can send both commands and responses
a. unbalanced
b. symmetrical
c. balanced
d. b and c
answer: C. balanced

40. In HDLC, the _______ describes which station has control of the link.
a. station type
b. configuration
c. mode of communication
d. any of the above
C. mode of communication

41. In the HDLC _______, the secondary device must have permission from the primary before it can transmit.
a. NRM (normal response mode)
b. ARM (asynchronous response mode)
c. ABM (asynchronous balanced mode)
d. any of the above
answer: A. NRM (normal response mode)

42. There are _______ types of HDLC frames.
a. 1
b. 2
c. 3
d. 4
answer: C. 3

43. An HDLC _______ is used to transport user data and control information.
a. I-frame
b. S-frame
c. U-frame
d. A-frame
answer: A. I-frame

44. An HDLC _______ can transport system management information.
a. I-frame
b. S-frame
c. U-frame
d. A-frame
answer: C. U-frame

45. The HDLC flag field is _______.
a. 01000010
b. 01010101
c. 10000001
d. 01111110
answer: D. 01111110

46. HDLC inserts a redundant 0 bit after the _______ consecutive 1 bit in the message data.
a. fifth
b. sixth
c. seventh
d. eighth
answer: A. fifth

47. If the HDLC flag field pattern is found in the message data field, it needs to be altered through _______
a. bit stuffing
b. byte stuffing
c. bit synchronization
d. byte synchronization
answer: A. bit stuffing

48. If the HDLC receiver counts more than six but less than fifteen consecutive 1s, this signifies _______
a. data
b. a flag
c. an abort
d. an idle channel
answer: C. an abort

49. If the HDLC receiver counts fifteen or more consecutive 1s, this signifies _______.
a. data
b. a flag
c. an abort
d. an idle channel
answer: D. an idle channel

50. If the HDLC receiver counts exactly six consecutive 1s, this signifies _______
a. data
b. a flag
c. an abort
d. an idle channel
answer: B. a flag

Module 04

1. We have categorized access methods into _______ groups.
a. two
b. three
c. four
d. five
answer: B. three

2. In ___________ methods, no station is superior to another station and none is assigned the control over another
a. random access
b. controlled access
c. channelization
d. none of the above
answer: A. random access

3. In ______, the chance of collision can be reduced if a station senses the medium before trying to use it.
a. MA
b. CSMA
c. FDMA
d. CDMA
answer: B. CSMA

4. _______ requires that each station first listen to the medium before sending.
a. MA
b. CSMA
d. FDMA
d. CDMA
answer: B. CSMA

5. __________ augments the CSMA algorithm to detect collision
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
answer: B. CSMA/CD

6. in ________, a station monitors the medium after it sends a frame to see if the transmission was successful. If so, the station is finished. If, however, there is a collision, the frame is sent again
a. CSMA/CA
b. CSMA/CD
c. both (a) and (b)
answer: B. CSMA/CD

7. To avoid collisions on wireless networks, ________was invented.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
answer: A. CSMA/CA

8. In _______, collisions are avoided through the use of three strategies: the interframe space, the contention window, and acknowledgments.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
answer: A. CSMA/CA

9. In _______ methods, the stations consult one another to find which station has the right to send
a. random access
b. controlled access
c. channelization
d. none of the above
answer: B. controlled access

10. In _______ methods, a station cannot send unless it has been authorized by other stations.
a. random access
b. controlled access
c. channelization
d. none of the above
answer: B. controlled access

11. We discussed ______ popular controlled-access methods
a. two
b. three
c. four
d. none of the above
answer: B. three

12. In the ________ method, a station needs to make a reservation before sending data. Time is divided into intervals.
a. reservation
b. polling
d. none of the above
answer: A. reservation

13. In the _____ method, time is divided into intervals. In each interval, a reservation frame precedes the data frames sent in that interval.
a. reservation
b. polling
c. token passing
d. none of the above
answer: A. reservation

14. In the ______ method, all data exchanges must be made through the primary device even when the ultimate destination is a secondary device.
a. reservation
b. polling
c. token passing
d. none of the above
B. polling

15. In the _______ method, the primary device controls the link; the secondary devices follow its instructions.
a. reservation
b. polling
c. token passing
d. none of the above
answer: B. polling

16. In the _______ method, the stations in a network are organized in a logical ring.
a. reservation
b. polling
c. token passing
d. none of the above
answer: C. token passing

17. In the _______ method, each station has a predecessor and a successor
a. reservation
b. polling
c. token passing
d. none of the above
answer: C. token passing

18. In the _________ method, a special packet called a ______ circulates through the ring.
a. reservation: control frame
b. polling: poll request
c. token passing: token
d. none of the above
answer: C. token passing: token

19. _______ is a multiple-access method in which the available bandwidth of a link is shared in time, frequency, or through code, between different stations
a. Random access
b. Controlled access
c. Channelization
d. none of the above
answer: C. Channelization

20. We discussed ________ channelization protocols
a. two
b. three
d. four
d. none of the above
answer: B. three

21. In ________, the available bandwidth is divided into frequency bands.
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: A. FDMA

22. In ______, each station is allocated a band to send its data. In other words, each band is reserved for a specific station, and it belongs to the station all the time.
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: A. FDMA

23. In _______, the stations share the bandwidth of the channel in time.
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: B. TDMA

24. In _____, each station is allocated a time slot during which it can send data. Each station transmits its data in its assigned time slot.
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: B. TDMA

25. In _____, each station transmits its data in its assigned time slot
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: B. TDMA

26. In ________ each station sends a frame whenever it has a frame to send.
a. pure ALOHA
b. slotted ALOHA
c. both (a) and (b)
d. neither (a) nor (b)
answer: A. pure ALOHA

27. In ______, the stations use different codes to achieve multiple access.
a. FDMA
b. TDMA
c. CDMA
d. none of the above
C. CDMA

28. In pure ALOHA, the vulnerable time is ______ the frame transmission time.
a. the same as
b. two times
c. three times
d. none of the above
answer: B. two times

29. _______ is based on coding theory and uses sequences of numbers called chips
a. FDMA
b. TDMA
c. CDMA
d. none of the above
answer: C. CDMA

30. The maximum throughput for pure ALOHA is ________ per cent.
a. 12.2
b. 18.4
c. 36.8
d. none of the above
answer: B. 18.4

31.In _______, the stations share the bandwidth of the channel in time.
A) FDMA
B) CDMA
C) TDMA
D)none of the above
Answer: C

32. In ______, the chance of collision can be reduced if a station senses the medium before trying to use it.
A) CSMA
B) MA
C) CDMA
D) FDMA
Answer: A

33. In the _______ method, the stations in a network are organized in a logical ring.
A) polling
B) token passing
C) reservation
D) none of the above
Answer: Option B

34. In _______, the sequences are generated using orthogonal codes such the Walsh tables.
A) TDMA
B) CDMA
C) FDMA
D) none of the above
Answer: B

35. __________ augments the CSMA algorithm to detect collision.
A) CSMA/CD
B) CSMA/CA
C) either (a) or (b)
D) both (a) and (b)
Answer: Option A

36. In the _________ method, after the station finds the line idle, it sends its frame immediately. If the line is not idle, it continuously senses the line until it finds it idle.
A) p-persistent
B) nonpersistent
C 1-persistent
D) none of the above
Answer: Option C

37. In the _____ method, time is divided into intervals. In each interval, a reservation frame precedes the data frames sent in that interval.
A) token passing
B) reservation
C) polling
D) none of the above
Answer: Option B

38. In the _______ method, each station has a predecessor and a successor.
A) token passing
B) polling
C) reservation
D) none of the above
Answer: Option A

39. The vulnerable time for CSMA is the ________propagation time.
A) three times
B) two times
C) the same as
D) none of the above
Answer: Option C

40. In the _________ method, a special packet called a ______ circulates through the ring.
A) polling: poll request
B) token passing: token
C) reservation: control frame
D) none of the above
Answer: Option B

41. The maximum throughput for pure ALOHA is ________ per cent.
A) 36.8
B) 18.4
C) 12.2
D) none of the above
Answer: Option B

42. In ________, the available bandwidth is divided into frequency bands.
A) TDMA
B) CDMA
C) FDMA
D) none of the above
Answer: Option C

43. In ___________ methods, no station is superior to another station and none is assigned the control over another.
A) controlled access
B) random access
C channelization
D none of the above
Answer: Option B

44. In the ________method, a station that has a frame to send senses the line. If the line is idle, it sends immediately. If the line is not idle, it waits a random amount of time and then senses the line again.
A) 1-persistent
B nonpersistent
C) p-persistent
D) none of the above
Answer: Option B

45. In ______, each station is allocated a band to send its data. In other words, each band is reserved for a specific station, and it belongs to the station all the time.
A) CDMA
B) FDMA
C) TDMA
D) none of the above
Answer: Option B

46. In the _______method, after the station finds the line idle it sends or refrain from sending based on the outcome of a random number generator. If the line is busy, it tries again.
A) p-persistent
B) nonpersistent
C) 1-persistent
D) none of the above
Answer: Option A

47. To avoid collisions on wireless networks, ________was invented.
A) CSMA/CD
B) CSMA/CA
C) either (a) or (b)
D) both (a) and (b)
Answer: Option B

48. In _____, each station is allocated a time slot during which it can send data. Each station transmits its data in its assigned time slot.
A) TDMA
B) CDMA
C) FDMA
D) none of the above
Answer: Option A

49. In the _______ method, the primary device controls the link; the secondary devices follow its instructions.
A) token passing
B) reservation
C) polling
D) none of the above
Answer: Option C

50. In _____, each station transmits its data in its assigned time slot.
A) TDMA
B) CDMA
C) FDMA
D) none of the above
Answer: Option A

Module 05

1. The network layer is concerned with __________ of data.
a) bits
b) frames
c) packets
d) bytes
Answer: c
Explanation: In computer networks, the data from the application layer is sent to the transport layer and is converted to segments. These segments are then transferred to the network layer and these are called packets. These packets are then sent to data link layer where they are encapsulated into frames. These frames are then transferred to physical layer where the frames are converted to bits.

2. Which one of the following is not a function of network layer?
a) routing
b) inter-networking
c) congestion control
d) error control
Answer: d
Explanation: In the OSI model, network layer is the third layer and it provides data routing paths for network communications. Error control is a function of the data link layer and the transport layer.

3. A 4 byte IP address consists of __________
a) only network address
b) only host address
c) network address & host address
d) network address & MAC address
Answer: c
Explanation: An ip address which is 32 bits long, that means it is of 4 bytes and is composed of a network and host portion and it depends on address class. The size of the host address and network address depends upon the class of the address in classful IP addressing.

4. In virtual circuit network each packet contains ___________
a) full source and destination address
b) a short VC number
c) only source address
d) only destination address
Answer: b
Explanation: A short VC number also called as VCID (virtual circuit identifier) is a type of identifier which is used to distinguish between several virtual circuits in a connection oriented circuit switched network. Each virtual circuit is used to transfer data over a larger packet switched network.

5. Which of the following routing algorithms can be used for network layer design?
a) shortest path algorithm
b) distance vector routing
c) link state routing
d) all of the mentioned
Answer: d
Explanation: The routing algorithm is what decides where a packet should go next. There are several routing techniques like shortest path algorithm, static and dynamic routing, decentralized routing, distance vector routing, link state routing, Hierarchical routing etc. The routing algorithms go hand in hand with the operations of all the routers in the networks. The routers are the main participants in these algorithms.

6. Which of the following is not correct in relation to multi-destination routing?
a) is same as broadcast routing
b) contains the list of all destinations
c) data is not sent by packets
d) there are multiple receivers
Answer: c
Explanation: In multi-destination routing, there is more than one receiver and the route for each destination which is contained in a list of destinations is to be found by the routing algorithm. Multi-destination routing is also used in broadcasting.

7. A subset of a network that includes all the routers but contains no loops is called ________
a) spanning tree
b) spider structure
c) spider tree
d) special tree
Answer: a
Explanation: Spanning tree protocol (STP) is a network protocol that creates a loop free logical topology for ethernet networks. It is a layer 2 protocol that runs on bridges and switches. The main purpose of STP is to ensure that you do not create loops when you have redundant paths in your network.

8. Which one of the following algorithm is not used for congestion control?
a) traffic aware routing
b) admission control
c) load shedding
d) routing information protocol
Answer: d
Explanation: The Routing Information Protocol (RIP) is used by the network layer for the function of dynamic routing. Congestion control focuses on the flow of the traffic in the network and uses algorithms like traffic aware routing, admission control and load shedding to deal with congestion.

9. The network layer protocol for internet is __________
a) ethernet
b) internet protocol
c) hypertext transfer protocol
d) file transfer protocol
Answer: b
Explanation: There are several protocols used in Network layer. Some of them are IP, ICMP, CLNP, ARP, IPX, HRSP etc. Hypertext transfer protocol is for application layer and ethernet protocol is for data link layer.

10. ICMP is primarily used for __________
a) error and diagnostic functions
b) addressing
c) forwarding
d) routing
Answer: a
Explanation: ICMP abbreviation for Internet Control Message Protocol is used by networking devices to send error messages and operational information indicating a host or router cannot be reached. ICMP operates over the IP packet to provide error reporting functionality as IP by itself cannot report errors.

11. Open Shortest Path First (OSPF) is also called as _____________
a) Link state protocol
b) Error-correction protocol
c) Routing information protocol
d) Border gateway protocol
Answer: a
Explanation: In OSPF, the link state of each path is checked, and then the shortest path is chosen among only the open state links. Each OSPF router monitors the cost of the link to each of its neighbors and then floods the link state information to other routers in the network.

12. The computation of the shortest path in OSPF is usually done by ____________
a) Bellman-ford algorithm
b) Routing information protocol
c) Dijkstra’s algorithm
d) Distance vector routing
Answer: c
Explanation: Shortest path in OSPF is usually computed by Dijkstra’s algorithm. It was proposed by Edsger W. Dijkstra in the year 1956. It is a greedy method algorithm and hence may not guarantee the shortest path every time, but is really fast.

13. Which of the following is false with respect to the features of OSPF?
a) Support for fixed-length subnetting by including the subnet mask in the routing message
b) More flexible link cost than can range from 1 to 65535
c) Use of designated router
d) Distribution of traffic over multiple paths that have equal cost to the destination
Answer: a
Explanation: OSPF provides support for variable-length sunbathing by including the subnet mask in the routing message. For fixed length subnets, there is no requirement for including the subnet mask in the routing message as there is just one subnet mask for all the subnets.

14. In OSPF, which protocol is used to discover neighbour routers automatically?
a) Link state protocol
b) Error-correction protocol
c) Routing information protocol
d) Hello protocol
Answer: d
Explanation: Hello protocol is used to discover neighboring routers automatically. It makes sure that the communication between neighbors is bidirectional. It’s similar to the real world moral construct of saying “Hello” to initialize the communication.

15. Which of the following is not a type of OSPF packet?
a) Hello
b) Link-state request
c) Link-state response
d) Link-state ACK
Answer: c
Explanation: The five types of OSPF packets are: Hello, Database description, Link-state request, Link-state update, and Link-state ACK. There is no Link-state response packet; the neighbor router sends a Link-state update packet as a response to the Link-state request packet if there is an update in the routing table

16. What is the correct order of the operations of OSPF?
i – Hello packets
ii – Propagation of link-state information and building of routing tables
iii – Establishing adjacencies and synchronization of database
a) i-ii-iii
b) i-iii-ii
c) iii-ii-i
d) ii-i-iii
Answer: b
Explanation: OSPF first implements a hello protocol. Then it later on tries to establish synchronisation with database. Later on building of routing tables is done.

17. In OSPF header, which field is used to detect errors in the packet?
a) Type
b) Area ID
c) Authentication type
d) Checksum
Answer: d
Explanation: Checksum field is used to detect errors. It makes sure that the data portions that are being sent are all in integrity. It can detect duplicated bits. Once an error is detected, the sender has to re-transmit the data as it won’t receive an acknowledgement.

18. In OSPF database descriptor packet, if there are more database descriptor packets in the flow, ‘M’ field is set to ____________
a) 1
b) 0
c) more
d) -1
Answer: a
Explanation: The “M” bit is the more bit, which indicates that there are more packets to be received in the descriptor packet flow whenever it is set to 1. There is also an “I” bit which indicates if the packet is first in the flow.

19. In OSPF database descriptor packet, which field is used to indicate that the router is master?
a) M
b) MS
c) I
d) Options
Answer: b
Explanation: The MS bit is used to indicate if the origin of the packet is a master or a slave. If it is set to 1, the source of the packet is a master, and if it is set to 0, the source of the packet is a slave.

20. In OSPF database descriptor packet, which field is used to detect a missing packet?
a) LSA header
b) MS
c) Database descriptor sequence number
d) Options
Answer: c
Explanation: Sequence number field is used to detect a missing packet. The packets are to be received in order of the sequence number, so if the receiver detects that there is a sequence number skipped or missing in the order, it stops processing the further received packets and informs the sender to retransmit the packets in sequence.

21. An OSPF router receives an LSA, the router checks its sequence number, and this number matches the sequence number of the LSA that the receiving router already has. What does the receiving router do with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers
Answer: a
Explanation: When the OSPF router receives an LSA, the router checks its sequence number. If this number matches the sequence number of the LSA that the receiving router already has, the router ignores the LSA.

22. An OSPF router receives an LSA. The router checks its sequence number and finds that this number is higher than the sequence number it already has. Which two tasks does the router perform with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers
Answer: b
Explanation: An OSPF router receives an LSA. If the router checks its sequence number and finds that the number is higher than the sequence number of the LSA that it already has, the router adds it to the database, and then floods the LSA to the other routers.

23. An OSPF router receives an LSA. The router checks its sequence number and finds that this number is lower than the sequence number it already has. What does the router do with the LSA?
a) ignores the LSA
b) adds it to the database
c) sends newer LSU update to source router
d) floods the LSA to the other routers
Answer: c
Explanation: An OSPF router receives an LSA. If the router checks its sequence number and finds that this number is lower than the sequence number that it already has, the router sends newer LSU update to source router. The router then adds it to the database and floods it to the other routers.

24. Each LSA has its own age timer. By default, how long does an LSA wait before requiring an update?
a) 30 seconds
b) 1 minute
c) 30 minutes
d) 1 hour
Answer: c
Explanation: Each LSA has its own age timer. By default, an LSA waits for 30 minutes before requiring an update. The router then has to send a LSR (Link State Request) to its neighbors to get an update.

25. Distance vector protocols use the concept of split horizon, but link-state routing protocols, such as OSPF, do not.
a) True
b) False
Answer: b
Explanation: In Distance vector routing protocols, there is a problem called count-to-infinity which occurs regularly. So, to make sure that it does not occur, the split horizon algorithm is used. There is no requirement for it in OSPF.

26. The outcome of Dijkstra’s calculation is used to populate the __________
a) Topology table
b) Routing table
c) Neighbor table
d) Adjacency table
Answer: b
Explanation: The outcome of Djikstra’s calculation is the main source of entries in the routing table as it is the algorithm that is used to find the shortest path in OSPF. The calculations are done after receiving every new LSU.

27. What is the IP protocol number for OSPF packets?
a) 89
b) 86
c) 20
d) 76
Answer: a
Explanation: 89 is the IP protocol number for OSPF packets. 86 is the protocol number for DGP, 76 is the protocol number for Backroom-SATNET-Monitoring and 20 is the protocol number for Host Monitoring Protocol.

28. Which packet is NOT an OSPF packet type?
a) LSU
b) LSR
c) DBD
d) Query
Answer: d
Explanation: LSU is the Link State Update packet, LSR is the Link State Request packet and DBD is the Database Descriptor packet in OSPF. Query packet is NOT an OSPF packet type.

29. Which multicast address does the OSPF Hello protocol use?
a) 224.0.0.5
b) 224.0.0.6
c) 224.0.0.7
d) 224.0.0.8
Answer: a
Explanation: Hello protocol is used to discover neighboring routers automatically. It makes sure that the communication between neighbors is bidirectional. The multicast address that the OSPF Hello protocol uses is 224.0.0.5.

30. The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers.
a) True
b) False
Answer: a
Explanation: The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers. It’s similar to the real world moral construct of saying “Hello” to initialize the communication.

31. Which of these is not applicable for IP protocol?
a) Connectionless
b) Offer reliable service
c) Offer unreliable service
d) Does not offer error reporting
Answer: b
Explanation: IP does not provide reliable delivery service for the data. It’s dependent upon the transport layer protocols like TCP to offer reliability.

32. Which of the following demerits does Fragmentation have?
a) Complicates routers
b) Open to DOS attack
c) Overlapping of fragments
d) All of the mentioned
Answer: d
Explanation: Fragmentation makes the implementation of the IP protocol complex and can also be exploited by attackers to create a DOS attack such as a teardrop attack. Fragmentation won’t be required if the transport layer protocols perform wise segmentation.

33. Which field helps to check rearrangement of the fragments?
a) Offset
b) Flag
c) TTL
d) Identifier
Answer: a
Explanation: The Fragment Offset field specifies where the fragment fits in the original datagram. The offset of the first fragment will always be 0. The size of the field (13 bits) is 3-bits shorter than the size of the total length field (16 bits).

34. In classless addressing, there are no classes but addresses are still granted in ______
a) IPs
b) Blocks
c) Codes
d) Sizes
Answer: b
Explanation: In classless addressing, there are no classes but addresses are still granted in blocks. The total number of addresses in a block of classless IP addresses = 2(32 – CIDR_value).

35. In IPv4 Addresses, classful addressing is replaced with ________
a) Classless Addressing
b) Classful Addressing
c) Classful Advertising
d) Classless Advertising
Answer: a
Explanation: Classful addressing is replaced with classless addressing as a large ratio of the available addresses in a class in calssful addressing is wasted. In classless addressing, one can reserve the number of IP addresses required by modifying the CIDR value and make sure that not many addresses are wasted.

36. First address in a block is used as network address that represents the ________
a) Class Network
b) Entity
c) Organization
d) Codes
Answer: c
Explanation: First address in a block is used as network address that represents the organization. The network address can be found by AND’ing any address in the block by the default mask. The last address in a block represents the broadcast address.

37. In classful addressing, a large part of available addresses are ________
a) Organized
b) Blocked
c) Wasted
d) Communicated
Answer: c
Explanation: In classful addressing, a large part of available addresses are wasted. Thus to solve this classful addressing is replaced with classless addressing where one can reserve the number of IP addresses required by modifying the CIDR value and make sure that not many addresses are wasted.

38. Network addresses are a very important concept of ________
a) Routing
b) Mask
c) IP Addressing
d) Classless Addressing
Answer: c
Explanation: Network addresses are a very important concept of IP addressing. The first address in a block is used as network address that represents the organization. The network address can be found by AND’ing any address in the block or class by the default mask.

39. Which of this is not a class of IP address?
a) Class E
b) Class C
c) Class D
d) Class F
Answer: d
Explanation: Class F is not a class of IP addressing. There are only five classes of IP addresses: Class A (0.0.0.0 to 127.255.255.255), Class B (128.0.0.0 to 191.255.255.255), Class C (192.0.0.0 to 223.255.255.255), Class D (224.0.0.0 to 239.255.255.255), and Class E (240.0.0.0 to 255.255.255.255).

40. DBD packets are involved during which two states?
a) Exstart and exchange
b) Loading and Two-way
c) Init and Full
d) Down and LoadingAnswer: a
Explanation: DBD stands for Database Descriptor. DBD packets are involved during the two states Exstart and Exchange. In exstart, the master and the slaves are decided and in the exchange state, the DBD is exchanged among the neighbors.

41. An OSPF router receives an LSA, the router checks its sequence number, and this number matches the sequence number of the LSA that the receiving router already has. What does the receiving router do with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers
Answer: a
Explanation: When the OSPF router receives an LSA, the router checks its sequence number. If this number matches the sequence number of the LSA that the receiving router already has, the router ignores the LSA.

42. An OSPF router receives an LSA. The router checks its sequence number and finds that this number is higher than the sequence number it already has. Which two tasks does the router perform with the LSA?
a) Ignores the LSA
b) Adds it to the database
c) Sends newer LSU update to source router
d) Floods the LSA to the other routers
Answer: b
Explanation: An OSPF router receives an LSA. If the router checks its sequence number and finds that the number is higher than the sequence number of the LSA that it already has, the router adds it to the database, and then floods the LSA to the other routers.

43. An OSPF router receives an LSA. The router checks its sequence number and finds that this number is lower than the sequence number it already has. What does the router do with the LSA?
a) ignores the LSA
b) adds it to the database
c) sends newer LSU update to source router
d) floods the LSA to the other routers
Answer: c
Explanation: An OSPF router receives an LSA. If the router checks its sequence number and finds that this number is lower than the sequence number that it already has, the router sends newer LSU update to source router. The router then adds it to the database and floods it to the other routers.

44. Each LSA has its own age timer. By default, how long does an LSA wait before requiring an update?
a) 30 seconds
b) 1 minute
c) 30 minutes
d) 1 hour
Answer: c
Explanation: Each LSA has its own age timer. By default, an LSA waits for 30 minutes before requiring an update. The router then has to send a LSR (Link State Request) to its neighbors to get an update.

45. Distance vector protocols use the concept of split horizon, but link-state routing protocols, such as OSPF, do not.
a) True
b) False
Answer: b
Explanation: In Distance vector routing protocols, there is a problem called count-to-infinity which occurs regularly. So, to make sure that it does not occur, the split horizon algorithm is used. There is no requirement for it in OSPF.

46. The outcome of Dijkstra’s calculation is used to populate the __________
a) Topology table
b) Routing table
c) Neighbor table
d) Adjacency table
Answer: b
Explanation: The outcome of Djikstra’s calculation is the main source of entries in the routing table as it is the algorithm that is used to find the shortest path in OSPF. The calculations are done after receiving every new LSU.

47. What is the IP protocol number for OSPF packets?
a) 89
b) 86
c) 20
d) 76
Answer: a
Explanation: 89 is the IP protocol number for OSPF packets. 86 is the protocol number for DGP, 76 is the protocol number for Backroom-SATNET-Monitoring and 20 is the protocol number for Host Monitoring Protocol.

48. Which packet is NOT an OSPF packet type?
a) LSU
b) LSR
c) DBD
d) Query
Answer: d
Explanation: LSU is the Link State Update packet, LSR is the Link State Request packet and DBD is the Database Descriptor packet in OSPF. Query packet is NOT an OSPF packet type.

49. Which multicast address does the OSPF Hello protocol use?
a) 224.0.0.5
b) 224.0.0.6
c) 224.0.0.7
d) 224.0.0.8
Answer: a
Explanation: Hello protocol is used to discover neighboring routers automatically. It makes sure that the communication between neighbors is bidirectional. The multicast address that the OSPF Hello protocol uses is 224.0.0.5.

50. The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers.
a) True
b) False
Answer: a
Explanation: The Hello protocol sends periodic updates to ensure that a neighbor relationship is maintained between adjacent routers. It’s similar to the real world moral construct of saying “Hello” to initialize the communication.

51. The size of an IP address in IPv6 is _________
a) 4 bytes
b) 128 bits
c) 8 bytes
d) 100 bits
Answer: b
Explanation: An IPv6 address is 128 bits long. Therefore, 2128 i.e. 340 undecillion addresses are possible in IPv6. IPv4 has only 4 billion possible addresses and IPv6 would be a brilliant alternative in case IPv4 runs out of possible new addresses.

52. The header length of an IPv6 datagram is ___________
a) 10bytes
b) 25bytes
c) 30bytes
d) 40bytes
Answer: d
Explanation: IPv6 datagram has fixed header length of 40bytes, which results in faster processing of the datagram. There is one fixed header and optional headers which may or may not exist. The fixed header contains the mandatory essential information about the packet while the optional headers contain the optional “not that necessary” information.

53. In the IPv6 header, the traffic class field is similar to which field in the IPv4 header?
a) Fragmentation field
b) Fast-switching
c) ToS field
d) Option field
Answer: c
Explanation: The traffic class field is used to specify the priority of the IP packet which is a similar functionality to the Type of Service field in the IPv4 header. It’s an 8-bit field and its values are not defined in the RFC 2460.

54. IPv6 does not use _________ type of address.
a) broadcast
b) multicast
c) anycast
d) unicast
Answer: a
Explanation: There is no concept of broadcast address in IPv6. Instead, there is an anycast address in IPv6 which allows sending messages to a group of devices but not all devices in a network. Anycast address is not standardized in IPv4.

55. Which among the following features is present in IPv6 but not in IPv4?
a) Fragmentation
b) Header checksum
c) Options
d) Anycast address
Answer: d
Explanation: There is an anycast address in IPv6 which allows sending messages to a group of devices but not all devices in a network. Anycast address is not standardized in IPv4.

56. The _________ field determines the lifetime of IPv6 datagram
a) Hop limit
b) TTL
c) Next header
d) Type of traffic
Answer: a
Explanation: The Hop limit value is decremented by one by a router when the datagram is forwarded by the router. When the value becomes zero the datagram is discarded. The field is 8-bits wide, so an IPv6 packet can live up to 255 router hops only.

57. Dual-stack approach refers to _________
a) implementing Ipv4 with 2 stacks
b) implementing Ipv6 with 2 stacks
c) node has both IPv4 and IPv6 support
d) implementing a MAC address with 2 stacks
Answer: c
Explanation: Dual-stack is one of the approaches used to support IPv6 in already existing systems. ISPs are using it as a method to transfer from IPv4 to IPv6 completely eventually due to the lower number of possible available addresses in IPv4.

58. Suppose two IPv6 nodes want to interoperate using IPv6 datagrams, but they are connected to each other by intervening IPv4 routers. The best solution here is ________
a) Use dual-stack approach
b) Tunneling
c) No solution
d) Replace the system
Answer: b
Explanation: The IPv4 routers can form a tunnel in which at the sender’s side, the IPv6 datagram is encapsulated in to IPv4, and at the receiver’s side of the tunnel, the IPv4 packet is stripped and the IPv6 packet is sent to the receiver.

59. Teredo is an automatic tunneling technique. In each client the obfuscated IPv4 address is represented by bits ______
a) 96 to 127
b) 0 to 63
c) 80 to 95
d) 64 to 79
Answer: a
Explanation: Teredo is a technique through which gives the possibility for full IPv6 network connectivity to IPv6 capable hosts which are currently on an IPv4 network. Bits 96 to 127 in the datagram represents obfuscated 1Pv4 address of the IPv4 network.

60. Which OSPF show command describes a list of OSPF adjacencies?
a) Show ip ospf interface
b) Show ip ospf
c) Show ip route
d) Show ip ospf neighbor
Answer: d
Explanation: The “Show ip ospf neighbor” command is the OSPF show command that can describe a list of OSPF adjacencies i.e. the list of adjacent nodes or neighbors. The router will only communicate with its neighbors directly.

61. Which of the following is the broadcast address for a Class B network ID using the default subnetmask?
a) 172.16.10.255
b) 255.255.255.255
c) 172.16.255.255
d) 172.255.255.255
Answer: c
Explanation: In this case, the class B network ID is 172.16.0.0. We know that the default mask of a class B network is 255.255.0.0. If we OR any address in a network with the complement of the default mask (0.0.255.255), we get the broadcast address of the network. In this case, the result of OR would be 172.16.255.255.

62. You have an IP address of 172.16.13.5 with a 255.255.255.128 subnet mask. What is your class of address, subnet address, and broadcast address?
a) Class A, Subnet 172.16.13.0, Broadcast address 172.16.13.127
b) Class B, Subnet 172.16.13.0, Broadcast address 172.16.13.127
c) Class B, Subnet 172.16.13.0, Broadcast address 172.16.13.255
d) Class B, Subnet 172.16.0.0, Broadcast address 172.16.255.255
Answer: b
Explanation: We know that the prefix 172 lies in class B (128 to 191) of IPv4 addresses. From the subnet mask, we get that the class is divided into 2 subnets: 172.16.13.0 to 172.16.13.127 and 172.16.13.128 to 172.16.13.255. The IP 172.16.13.5 lies in the first subnet. So the starting address 172.16.13.0 is the subnet address and last address 172.16.13.127 is the broadcast address.

63. If you wanted to have 12 subnets with a Class C network ID, which subnet mask would you use?
a) 255.255.255.252
b) 255.255.255.255
c) 255.255.255.240
d) 255.255.255.248
Answer: c
Explanation: If you have eight networks and each requires 10 hosts, you would use the Class C mask of 255.255.255.240. Why? Because 240 in binary is 11110000, which means you have four subnet bits and four host bits. Using our math, we’d get the following:
24-2=14 subnets
24-2=14 hosts.

64. The combination of _________ and __________ is often termed the local address of the local portion of the IP address.
a) Network number and host number
b) Network number and subnet number
c) Subnet number and host number
d) Host number
Answer: c
Explanation: It is termed as the local address because the address won’t be applicable outside the subnet. Sub networking is implemented for remote sensing in transparent way from that host which is contained in the sub network which called a local operation.

65. _________ implies that all subnets obtained from the same subnet mask.
a) Static subnetting
b) Dynamic subnetting
c) Variable length subnetting
d) Dynamic length subnetting
Answer: a
Explanation: Static subnetting is used when the requirement is of same number of hosts in each subnet for the institution. The same subnet mask can be used to find the subnet id of each subnet. It is usually used to divide large networks into smaller parts.

66. State whether true or false.
i) A connection oriented protocol can only use unicast addresses.
ii) The any cast service is included in IPV6.
a) True, True
b) True, False
c) False, True
d) False, False
Answer: a
Explanation: In a connection oriented protocol, the host can only establish connection with another host on one unique channel, that’s why it can only use unicast addresses. In IPv6, there is an anycast address in IPv6 which allows sending messages to a group of devices but not all devices in a network.

67. __________ is a high performance fiber optic token ring LAN running at 100 Mbps over distances upto 1000 stations connected.
a) FDDI
b) FDDT
c) FDDR
d) FOTR
Answer: a
Explanation: FDDI stands for Fiber Distributed Data Interface. It is a set of standards for fiber optic token ring LANs running at 100 Mbps over distances up to 200 km in diameter and 1000 stations connected.

68. Which of the following are Gigabit Ethernets?
a) 1000 BASE-SX
b) 1000 BASE-LX
c) 1000 BASE-CX
d) All of the mentioned
Answer: d
Explanation: In computer networking, Gigabit Ethernet (GbE or 1 GigE) is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second (1,000,000,000 bits per second), as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks, as a result of being considerably faster.

69. _________ is a collective term for a number of Ethernet Standards that carry traffic at the nominal rate of 1000 Mbit/s against the original Ethernet speed of 10 Mbit/s.
a) Ethernet
b) Fast Ethernet
c) Gigabit Ethernet
d) Gigabyte Ethernet
Answer: b
Explanation: Fast Ethernet is a set of Ethernet Standards which were introduced in 1995, that carry traffic at the nominal rate of 1000 Mbit/s. 100BASE-TX is the most commonly used Fast Ethernet standard.

70. _________ is another kind of fiber optic network with an active star for switching.
a) S/NET
b) SW/NET
c) NET/SW
d) FS/NET
Answer: a
Explanation: A 50-MBd active star fiber optical Local area network (LAN) and its optical combiner and mixing rod splitter are presented. The limited power budget and relatively large tapping losses of light wave technology, which limit the use of fiber optics in tapped bus LAN topologies, are examined and proven tolerable in optical star topologies.

71. EIGRP is a routing protocol design by Cisco.
a) True
b) False
Answer: a
Explanation: EIGRP stands for Enhanced Interior Gateway Routing Protocol is a routing protocol designed by Cisco. It is available only on Cisco routers.

72. EIGRP metric is ________
a) K-values
b) Bandwidth only
c) Hop Count
d) Delay only
Answer: a
Explanation: EIGRP metric is K-values which are integers from 0 to 128. They are used to calculate the overall EIGRP cost with bandwidth and delay metrics.

73. EIGRP can support ____________
a) VLSM/subnetting
b) Auto summary
c) Unequal cast load balancing
d) All of the mentioned
Answer: d
Explanation: EIGRP supports variable and fixed length subnetting, Auto summary, and Unequal cast load balancing to provide efficient routing functionality on Cisco routers.

74. EIGRP sends a hello message after every ___________ seconds.
a) 5 seconds (LAN), 60 seconds (WAN)
b) 5 seconds (LAN), 5 seconds (WAN)
c) 15s
d) 180s
Answer: a
Explanation: EIGRP routers broadcast the hello packets frequently to familiarize with the neighbors. EIGRP routers send the hello message after every 5 seconds on LAN, and every 60 seconds on WAN.

75. Administrative distance for internal EIGRP is ______
a) 90
b) 170
c) 110
d) 91
Answer: a
Explanation: Routers use the metric of administrative distance to select the best path when there are different routes to the same destination from two different routing protocols as it is a measure of reliability of routing protocols. Administrative distance for internal EIGRP is 90.

76. The EIGRP metric values include:
a) Delay
b) Bandwidth
c) MTU
d) All of the mentioned
Answer: d
Explanation: The EIGRP metric values are Delay, Bandwidth, and MTU. MTU stands for Maximum Transmission Unit. They are combined together to give the overall EIGRP cost in K-values.

77. For default gateway, which of following commands will you use on a Cisco router?
a) IP default network
b) IP default gateway
c) IP default route
d) Default network
Answer: a
Explanation: IP default network command is used to find the default gateway in Cisco router. If the router finds routes to the node, it considers the routes to that node for installation as the gateway to it.

78. Administrative distance for external EIGRP route is _______
a) 90
b) 170
c) 110
d) 100
Answer: b
Explanation: Routers use the metric of administrative distance to select the best path when there are different routes to the same destination from two different routing protocols as it is a measure of reliability of routing protocols. Administrative distance for external EIGRP is 170.

79. EIGRP uses the ____________ algorithm for finding shortest path.
a) SPF
b) DUAL
c) Linkstat
d) Djikstra’s
Answer: b
Explanation: EIGRP uses the DUAL algorithm for finding shortest path. DUAL stands for diffusing update algorithm and it is used to prevent routing loops by recalculating routes globally.

80. In EIGRP best path is known as the successor, where as backup path is known as __________
a) Feasible successor
b) Back-up route
c) Default route
d) There is no backup route in EIGRP
Answer: a
Explanation: Feasible successor is the backup path. The backup path is used alternatively used whenever the best path fails. It is not used primarily because it is comparatively expensive than the best path.

Module 06

1. An IP packet is called a _____________.
a. user datagram
b. segment
c. datagram
d. none of the above
answer: C. datagram

2. A TCP packet is called a _____________.
a. user datagram
b. segment
c. datagram
d. none of the above
answer: B. segment

3. A UDP packet is called a _____________.
a. user datagram
b. segment
c. datagram
d. none of the above
answer: A. user datagram

4. An IP packet is encapsulated in a _____________.
a. data link frame
b. network layer packet
c. physical layer packet
d. none of the above
answer: A. data link frame

5. A TCP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: B. IP datagram

6. A UDP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: B. IP datagram

7. An ARP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: A. data link frame

8. A RARP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: A. data link frame

9. An ICMP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: B. IP datagram

10. An IGMP packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
c. physical layer packet
d. none of the above
answer: B. IP datagram

11. An application-layer packet is encapsulated in a(n) _____________.
a. data link frame
b. IP datagram
d. none of the above
answer: C. TCP or UDP packet

12. An IP address is _________ bits.
a. 24
b. 32
c. 48
d. none of the above
answer: B. 32

13. An IP address is _______ bytes in dotted decimal notation.
a. 3
b. 4
c. 5
d. none of the above
answer: B. 4

14. A class B address starts with the _________bit(s).
a. 0
b. 10
c. 110
d. 1111
answer: B. 10

15. A class E address starts with the _________bit(s).
a. 0
b. 10
c. 1110
d. 1111
answer: D. 1111

16. A class C address starts with the _________bit(s).
a. 0
b. 10
c. 110
d. 1110
answer: C. 110

17. A class A address starts with the _________bit(s).
a. 0
b. 10
c. 1110
d. 1111
answer: A. 0

18. A class D address starts with the _________bit(s).
a. 0
b. 10
c. 1110
d. 1111
answer: C. 1110

19. What is the class of the address 227.78.19.21?
a. A
b. B
c. C
d. D
answer: D. D

20. What is the class of the address 130.8.119.1?
a. A
b. B
c. C
d. D
answer: B. B

21. Which of the following is false with respect to TCP?
a) Connection-oriented
b) Process-to-process
c) Transport layer protocol
d) Unreliable
Answer: d
Explanation: TCP is a transport layer protocol that provides reliable and ordered delivery of a stream of bytes between hosts communicating via an IP network.

22. In TCP, sending and receiving data is done as _______
a) Stream of bytes
b) Sequence of characters
c) Lines of data
d) Packets
Answer: a
Explanation: TCP provides stream oriented delivery between hosts communicating via an IP network and there are no message boundaries. TCP can concatenate data from a number of send () commands into one stream of data and still transmit it reliably.

23. TCP process may not write and read data at the same speed. So we need __________ for storage.
a) Packets
b) Buffers
c) Segments
d) Stacks
Answer: b
Explanation: A TCP receiver has a receive buffer that is used to store the unprocessed incoming packets in case the sender is sending packets faster than the processing rate of the received packets.

24. TCP groups a number of bytes together into a packet called _______
a) Packet
b) Buffer
c) Segment
d) Stack
Answer: c
Explanation: A segment may be collection of data from many send () statements. TCP transmits each segment as a stream of bytes.

25. Communication offered by TCP is ________
a) Full-duplex
b) Half-duplex
c) Semi-duplex
d) Byte by byte
Answer: a
Explanation: Data can flow both the directions at the same time during a TCP communication hence, it is full-duplex. This is the reason why TCP is used in systems that require full-duplex operation such as e-mail systems.

26. To achieve reliable transport in TCP, ___________ is used to check the safe and sound arrival of data.
a) Packet
b) Buffer
c) Segment
d) Acknowledgment
Answer: d
Explanation: Acknowledgment mechanism is used to check the safe and sound arrival of data. The sender actively checks for acknowledgement from the receiver and once a specific time period has passed, it retransmits the data.

27. In segment header, sequence number and acknowledgement number fields refer to _______
a) Byte number
b) Buffer number
c) Segment number
d) Acknowledgment

28. Suppose a TCP connection is transferring a file of 1000 bytes. The first byte is numbered 10001. What is the sequence number of the segment if all data is sent in only one segment?
a) 10000
b) 10001
c) 12001
d) 11001
Answer: b
Explanation: The sequence number given to first byte of a segment, with respect to its order among the previous segments, is the sequence number of that segment.

29. Bytes of data being transferred in each connection are numbered by TCP. These numbers start with a _________
a) Fixed number
b) Random sequence of 0’s and 1’s
c) One
d) Sequence of zero’s and one’s
Answer: d
Explanation: One might expect the sequence number of the first byte in the stream to be 0, or 1. But that does not happen in TCP, Instead, the sender has to choose an Initial Sequence Number (ISN), which is basically a random 32 bit sequence of 0’s and 1’s, during the connection handshake.

30. The value of acknowledgement field in a segment defines _______
a) sequence number of the byte received previously
b) total number of bytes to receive
c) sequence number of the next byte to be received
d) sequence of zeros and ones
Answer: c
Explanation: The acknowledgement field in a segment defines the sequence number of the byte which is to be received next i.e. sequence number of byte that the sender should transmit next.

31. Which of the following is false with respect to UDP?
a) Connection-oriented
b) Unreliable
c) Transport layer protocol
d) Low overhead
Answer: a
Explanation: UDP is an unreliable, connectionless transport layer protocol that provides message-based data transmission. TCP is an example of connection-oriented protocols.

32. Return value of the UDP port “Chargen” is _______
a) String of characters
b) String of integers
c) Array of characters with integers
d) Array of zero’s and one’s
Answer: a
Explanation: Using Chargen with UDP on port 19, the server sends a UDP datagram containing a random number of characters every time it receives a datagram from the connecting host. The number of characters is between 0 and 512.

33. Beyond IP, UDP provides additional services such as _______
a) Routing and switching
b) Sending and receiving of packets
c) Multiplexing and demultiplexing
d) Demultiplexing and error checking
Answer: d
Explanation: De-multiplexing is the delivering of received segments to the correct application layer processes at the recipients end using UDP. Error checking is done through checksum in UDP.

34. What is the main advantage of UDP?
a) More overload
b) Reliable
c) Low overhead
d) Fast
Answer: c
Explanation: As UDP does not provide assurance of delivery of packet, reliability and other services, the overhead taken to provide these services is reduced in UDP’s operation. Thus, UDP provides low overhead, and higher speed.

35. Port number used by Network Time Protocol (NTP) with UDP is ________
a) 161
b) 123
c) 162
d) 124
Answer: b
Explanation: The Network Time Protocol is a clock synchronization network protocol implemented by using UDP port number 123 to send and receive time stamps.

36. What is the header size of a UDP packet?
a) 8 bytes
b) 8 bits
c) 16 bytes
d) 124 bytes
Answer: a
Explanation: The fixed size of the UDP packet header is 8 bytes. It contains four two-byte fields: Source port address, Destination port address, Length of packet, and checksum.

37. The port number is “ephemeral port number”, if the source host is _______
a) NTP
b) Echo
c) Server
d) Client
Answer: d
Explanation: Port numbers from 1025 to 5000 are used as ephemeral port numbers in Windows Operating System. Ephemeral port numbers are short-lived port numbers which can be used for clients in a UDP system where there are temporary clients all the time.

38. “Total length” field in UDP packet header is the length of _________
a) Only UDP header
b) Only data
c) Only checksum
d) UDP header plus data
Answer: d
Explanation: Total length is the 16 bit field which contains the length of UDP header and the data. The maximum value of the Total length field and the maximum size of a UDP datagram is 65,535 bytes (8 byte header + 65,527 bytes of data).

39. Which is the correct expression for the length of UDP datagram?
a) UDP length = IP length – IP header’s length
b) UDP length = UDP length – UDP header’s length
c) UDP length = IP length + IP header’s length
d) UDP length = UDP length + UDP header’s length
Answer: a
Explanation: A user datagram is encapsulated in an IP datagram. There is a field in the IP header that defines the total length of the IP packet. There is another field in the IP header that defines the length of the header. So if we subtract the length of the IP header that is encapsulated in the IP packet, we get the length of UDP datagram.

40. The ______ field is used to detect errors over the entire user datagram.
a) udp header
b) checksum
c) source port
d) destination port
Answer: b
Explanation: Checksum field is used to detect errors over the entire user datagram. Though it is not as efficient as CRC which is used in TCP, it gets the job done for the UDP datagram as UDP doesn’t have to ensure the delivery of the packet.

41. The receiver of the data controls the amount of data that are to be sent by the sender is referred to as ___________
a) Flow control
b) Error control
c) Congestion control
d) Error detection
Answer: a
Explanation: Flow control is done to prevent the receiver from being overflowed with data. It is done using various open-loop (prevention) methods and closed-loop (recovery) methods.

42. Size of TCP segment header ranges between ___________
a) 16 and 32 bytes
b) 16 and 32 bits
c) 20 and 60 bytes
d) 20 and 60 bits
Answer: c
Explanation: The size of the header can be 20 bytes at a minimum if there are no options and can go up to 60 bytes at maximum with 40 bytes in the options field. The header contains all the control information required to ensure ordered, error-free and reliable delivery of the segment.

43. Connection establishment in TCP is done by which mechanism?
a) Flow control
b) Three-Way Handshaking
c) Forwarding
d) Synchronization
Answer: b
Explanation: A three-way handshake allows both, the server and the client to choose their Initial Sequence Number and inform about it to the other party. This won’t be possible using the two-way handshake mechanism.

44. The server program tells its TCP that it is ready to accept a connection. This process is called ___________
a) Active open
b) Active close
c) Passive close
d) Passive open
Answer: d
Explanation: This is the first step in the Three-Way Handshaking process and is started by the server. Then the Client picks an ISN (Initial Sequence Number) and synchronizes (shares) it with the Server requesting a connection. The Server acknowledges the clients ISN, and then picks an ISN and synchronizes it with the Client. At last, the Client acknowledges the servers ISN.

45. A client that wishes to connect to an open server tells its TCP that it needs to be connected to that particular server. The process is called ___________
a) Active open
b) Active close
c) Passive close
d) Passive open
Answer: a
Explanation: This is the second step in the Three-Way Handshaking process and is done by the client once it finds the open server and picks an ISN. The Server acknowledges the clients request, and then picks an ISN and synchronizes it with the Client. At last, the Client acknowledges the servers ISN.

46. In Three-Way Handshaking process, the situation where both the TCP’s issue an active open is ___________
a) Mutual open
b) Mutual Close
c) Simultaneous open
d) Simultaneous close
Answer: c
Explanation: In simultaneous open situation, two nodes send an SYN signal to each other and start a TCP connection. Here, both TCP nodes transmit a SYNC+ACK segment to each other and a connection is established between them. This doesn’t happen usually, because both sides have to know which port on the other side to send to.

47. A malicious attacker sends a large number of SYNC segments to a server, pretending that each of them is coming from a different client by faking the source IP address in the datagram. Which type of attack is being performed in this situation?
a) SYNC flooding attack
b) Active attack
c) Passive attack
d) Denial-of-service attack
Answer: a
Explanation: SYNC flooding attack is a form of Denial of Service attack. Due to the overflow of SYNC segments sent to the server, the victims are not able to request for a connection to the server, thus resulting in Denial of Service.

48. SYNC flooding attack belongs to a type of security attack known as ___________
a) SYNC flooding attack
b) Active attack
c) Passive attack
d) Denial-of-service attack
Answer: d
Explanation: During SYNC flooding the system collapses and denies service to every request, making it a DoS attack. Some other DoS attacks are bandwidth flooding, connection flooding and UDP flooding.

49. The sizes of source and destination port address in TCP header are ___________ respectively.
a) 16-bits and 32-bits
b) 16-bits and 16-bits
c) 32-bits and 16-bits
d) 32-bits and 32-bits
Answer: b
Explanation: All port addresses are of 16 bits and they specify the type of service being used by the network entity. For example, port 21 is used for FTP connections and port 25 is used for ICMP connections.

50. What allows TCP to detect lost segments and in turn recover from that loss?
a) Sequence number
b) Acknowledgment number
c) Checksum
d) Both Sequence & Acknowledgment number
Answer: b
Explanation: TCP header contains separate fields for sequence number and acknowledgment number. Comparing these values is what allows TCP to detect lost segments and in turn recover from that loss. After detecting the lost segments, the recovery may require retransmission of the lost segments of data.

51. TCP is a ………. protocol.
A. stream-oriented
B. message-oriented
C. block-oriented
D. packet-oriented
answer: A

52. Which of the following is not the layer of TCP/IP protocol.
A. Physical layer
B. link layer
C. network layer
D. transport layer.
answer: A

53.TCP groups a number of bytes together into a packet called a ….
A. user datagram
B. segment
C. datagram
D. packet
answer: B

54. The ………. of TCP/IP protocol is responsible for figuring out how to get data to its destination.
A. application layer
B. link layer
C. network layer
D. transport layer.
answer: C

55. TCP is a(n) ……….. transport protocol.
A. protocol delivery
B. reliable
C. best-effort delivery
D. effortless delivery
answer: B

6 ……… is the protocol that hides the underlying physical network by creating a virtual network view.
A. Internet Protocol(IP)
B. Internet Control Message Protocol(ICMP)
C. Address Resolution Protocol(ARP)
D. Bootstrap Protocol(BOOTP)
answer: A

57. To use the services of UDP, we need ……… socket addresses.
A. four
B. two
C. three
D. four
answer: C

58. Which of the following is not the name of Regional Internet Registries(RIR) to administer the network number portion of IP address.
A. American Registry for Internet Numbers(ARIN)
B. Reseaux IP Europeans(RIPE)
C. Europeans Registry for Internet Numbers(ERIN)
D. Asia Pacific Network Information Center(APNIC)
answer:  C

59. UDP packets are called …….
A. user datagrams
B. segments
C. frames
D. packets
answer:A

60. ………… addresses use 21 bits for the and 8 bits for the portion of the IP address for TCP/IP network.
A. Class A
B. Class B
C. Class C
D. Class D
answer: C

61. UDP packets have a fixed-size header of ………. bytes.
A. 16
B. 8
C. 32
D. 64
answer:B

62. ………. messages are never sent in response to datagrams with a broadcast or a multicast destination address.
A. ICMP
B. ARP
C. IP
D. BOOTP
answer: A

63. TCP assigns a sequence number to each segment that is being sent. The sequence number for each segment is the number of the ……. byte carried in that segment.
A. first
B. last
C. middle
D. zero
answer: A

64. ………. is responsible for converting the higher-level protocol address (IP addresses) to physical network addresses.
A. Internet Protocol(IP)
B. Internet Control Message Protocol(ICMP)
C. Address Resolution Protocol(ARP)
D. Bootstrap Protocol(BOOTP)
answer: C

65. UDP and TCP are both ……… layer protocols.
A. data link
B. network
C. transport
D. interface
answer: C

66. ……….. is a process-to-process protocol that adds only port addresses, checksum error control, and length information to the data from the upper layer.
A. TCP
B. UDP
C. IP
D. ARP
answer: B

67. Which of the following functions does UDP perform?
A. Process-to-process communication
B. Host-to-host communication
C. End-to-end reliable data delivery
D. Interface-to-interface communication.
answer: A

68. A port address in TCP/IP is ………bits long.
A. 32
B. 48
C. 16
D. 64
answer: C

69.B When the IP layer of a receiving host receives a datagram, …..
A. delivery is complete
B. a transport layer protocol takes over
C. a header is added
D. a session layer protocol takes over

70). TCP/IP is a ………. hierarchical protocol suite developed before the OSI model.
A. seven-layer
B. five-layer
C. six-layer
D. four-layer
answer: B

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