Consider the following statements I. TCP connections are full duplex II. TCP has no option for selective acknowledgment III. TCP connections are message streams

All of I, II, and III are correct

Using public key cryptography, X adds a digital signature to message M, encrypts and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations?

Encryption: X s private key followed by Y s private key; Decryption: X s public key followed by Y s private key

Encryption: X s private key followed by Y s public key; Decryption: X s public key followed by Y s private key

Encryption: X s public key followed by Y s private key; Decryption: Y s public key followed by X s private key

Encryption: X s private key followed by Y s public key; Decryption: Y s private key followed by X s public key

In a network of LANs connected by bridges, packets are sent from one LAN to another through intermediate bridges. Since, more than one path may exist between two LANs, packets may have to be routed through multiple bridges. Why is the spanning tree algorithm used for bridge-routing?

For shortest path routing between LANs

For avoiding loops in the routing paths

101 + Mcqs in Computer networks miscellaneous in Computer Networks Page 1 McqOptions

1.	A sender S sends a message m to receiver R. which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place. (I) S can launch a birthday attack to replace m with a fraudulent message. (II) A third party attacker can launch a birthday attack to replace m with a fraudulent message. (III) R can launch a birthday attack to replace m with a fraudulent message. Which of the following are possible security violations?
A.	(I) and (II) only
B.	(I) only
C.	(II) only
D.	(II) and (III) only
Answer» C. (II) only

Discussion

2.	Consider a network connecting two systems located 8000 kilometers apart. The bandwidth of the network is 500 10⁶ bits per second. The propagation speed of the media is 4 10⁶ meters per second. It is needed to design a Go Back N sliding window protocol for this network. The average packet size is 10⁷ bits. The network is to be used to its full capacity. Assume that processing delays at nodes are negligible. Then, the minimum size in bits of the sequence number field has to be _________.
A.	8
B.	4
C.	2
D.	0
Answer» B. 4

Discussion

3.	Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (10⁸ bits per second) over a 1 km (kilometer) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/ sec) in the cable?
A.	8000
B.	10000
C.	16000
D.	20000
Answer» E.

Discussion

4.	Consider a LAN with four nodes S₁ S₂ , S₃ and S₄. Time is divided into fixed-size slots, and a node can begin its transmission only at the beginning of a slot. A collision is said to have occurred if more than one node transmit in the same slot. The probability of generation of a frame in a time slot by S₁, S₂, S₃ and S₄ are 0.1, 0.2, 0.3 and 0.4, respectively. The probability of sending a frame in the first slot without any collision by any of these four stations is ________.
A.	10.4404
B.	1.4404
C.	0.4404
D.	None of these
Answer» D. None of these

Discussion

5.	A network has a data transmission bandwidth of 20 10⁶ bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 micro seconds. The minimum size of a frame in the network is ________ bytes.
A.	200 bytes
B.	100 bytes
C.	500 bytes
D.	1000 bytes
Answer» B. 100 bytes

Discussion

6.	For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE? I. At least three non-overlapping channels are available for transmissions. II. The RTS-CTS mechanism is used for collision detection. III. Unicast frames are ACKed.
A.	II, and III
B.	I and III only
C.	II and III only
D.	II only
Answer» C. II and III only

Discussion

7.	In the RSA public key cryptosystem, the private and public keys are (e, n) and (d, n) respectively, where n = p*q and p and q are large primes. Besides, n is public and p and q are private. Let M be an integer such that 0 < M < n and (n) = (p 1) (q 1). Now consider the following equations. 1. M = M^e mod n M = (M )^d mod n 2. ed 1 mod n 3. ed = 1 mod n 4. M = M^e mod n M = (M )^d mod n Which of the above equations correctly represent RSA cryptosystem?
A.	1 and 2
B.	1 and 3
C.	2 and 4
D.	3 and 4
Answer» C. 2 and 4

Discussion

8.	Which of the following are used to generate a message digest by the network security protocols? (P) RSA (Q) SHA-1 (R) DES (S) MD5
A.	(P) and (R) only
B.	(Q) and (R) only
C.	(Q) and (S) only
D.	(R) and (S) only
Answer» D. (R) and (S) only

Discussion

9.	A 2 km long broadcast LAN has 10⁷ bps bandwidth and uses CSMA/CD. The signal travels along the wire at 2 10⁸ m/s. What is the minimum packet size that can be used on this network?
A.	50 bytes
B.	100 bytes
C.	200 bytes
D.	None of these
Answer» E.

Discussion

10.	The message 11001001 is to be transmitted using the CRC polynomial x³ + 1 to protect it from errors. The message that should be transmitted is
A.	11001001000
B.	11001001011
C.	11001010
D.	110010010011
Answer» C. 11001010

Discussion

11.	An IP machine Q has a path to another IP machine H via three IP routers R1, R2, and R3. Q R1 R2 R3 H H acts as an HTTP server, and Q connects to H via HTTP and downloads a file. Session layer encryption is used, with DES as the shared key encryption protocol. Consider the following four pieces of information: [I1] The URL of the file downloaded by Q [I2] The TCP port numbers at Q and H [I3] The IP addresses of Q and H [I4] The link layer addresses of Q and H Which of I1, I2, I3, and I4 can an intruder learn through sniffing at R2 alone?
A.	Only I1 and I2
B.	Only I1
C.	Only I2 and I3
D.	Only I3 and I4
Answer» D. Only I3 and I4

Discussion

12.	Consider the following statements about the routing protocols. Routing Information Protocol (RIP) and Open Shortest Path First (OSPF) in an IPv4 network. I : RIP uses distance vector routing II : RIP packets are sent using UDP III : OSPF packets are sent using TCP IV : OSPF operation is based on link-state routing Which of the statements above are CORRECT?
A.	I and IV only
B.	I, II and III only
C.	I, II and IV only
D.	II, III and IV only
Answer» D. II, III and IV only

Discussion

13.	Consider the following statements I. TCP connections are full duplex II. TCP has no option for selective acknowledgment III. TCP connections are message streams
A.	Only I is correct
B.	Only I and III are correct
C.	Only II and III are correct
D.	All of I, II, and III are correct
Answer» B. Only I and III are correct

Discussion

14.	What is the rate at which application data is transferred to host H_C ? Ignore errors, acknowledgements, and other overheads.
A.	325.5 kbps
B.	354.5 kbps
C.	409.6 kbps
D.	512.0 kbps
Answer» C. 409.6 kbps

Discussion

15.	Host A (on TCP/IP v4 network A) sends an IP datagram D to host B (also on TCP/IP v4 network B). Assume that no error occurred during the transmission of D. When D reaches B, which of the following IP header field(s) may be different from that of the original datagram D? (i) TTL (ii) Checksum (iii) Fragment Offset
A.	(i) only
B.	(i) and (ii) only
C.	(ii) and (iii) only
D.	(i), (ii) and (iii)
Answer» E.

Discussion

16.	Suppose two hosts use a TCP connection to transfer a large file. Which of the following statements is/are FALSE with respect to the TCP connection? I. If the sequence number of a segment is m, then the sequence number of the subsequent segment is always m + 1. II. If the estimated round trip time at any given point of time is t sec the value of the retransmission timeout is always set to greater than or equal to t sec. III. The size of the advertised window never changes during the curse of the TCP connection. IV. The number of unacknowledged bytes at the sender is always less than or equal to the advertised window.
A.	III only
B.	I and III only
C.	I and IV only
D.	II and IV only
Answer» C. I and IV only

Discussion

17.	Identify the correct order in which the following actions take place in an interaction between a web browser and a web server. 1. The web browser requests a webpage using HTTP. 2. The web browser establishes a TCP connection with the web server. 3. The web server sends the requested webpage using HTTP. 4. The web browser resolves the domain name using DNS.
A.	4, 2, 1, 3
B.	1, 2, 3, 4
C.	4, 1, 2, 3
D.	2, 4, 3 , 1
Answer» B. 1, 2, 3, 4

Discussion

18.	Which of the following is/are example(s) of stateful application layer protocols? (i) HTTP (ii) FTP (iii) TCP (iv) POP3
A.	(i) and (ii) only
B.	(ii) and (iii) only
C.	(ii) and (iv) only
D.	(iv) only
Answer» D. (iv) only

Discussion

19.	Consider a token ring network with a length of 2 km having 10 stations including a monitoring station. The propagation speed of the signal is 2 10⁸ m/s and the token transmission time is ignored. If each station is allowed to hold the token for 2 msec, the minimum time for which the monitoring station should wait (in m sec)before assuming that the token is lost is _______.
A.	28 to 30 sec.
B.	21 to 30 sec.
C.	20 to 24 sec.
D.	38 to 40 sec.
Answer» B. 21 to 30 sec.

Discussion

20.	Suppose that the sliding window protocol is used with the sender window size of 2¹, where 1 is the number of its identified in the earlier part and acknowledgments are always piggy backed. After sending 2¹ frames, what is the minimum time, the sender will have to wait before starting transmission of the next frame? (Identify the closest choice ignoring the frame processing time.)
A.	16 ms
B.	18 ms
C.	20 ms
D.	22 ms
Answer» C. 20 ms

Discussion

21.	Consider a binary code that consists of only four valid codewords as given below : 00000,01011,10101,11110 Let the minimum Hamming distance of the code be p and the maximum number of erroneous bits that can be corrected by the code be q. Then the values of p and q are
A.	p = 3 and q = 1
B.	p = 3 and q = 2
C.	p = 4 and q = 1
D.	p = 4 and q = 2
Answer» C. p = 4 and q = 1

Discussion

22.	Consider two hosts X and Y, connected by a single direct link of rate 10⁶ bits/sec. The distance between the two hosts is 10,000 km and the propagation speed along the link is 2 10⁸ m/sec. Host X sends a file of 50,000 bytes as one large message to host Y continuously. Let the transmission and propagation delays be p milliseconds and q milliseconds, respectively. Then the values of p and q are
A.	p = 50 and q = 100
B.	p = 50 and q = 400
C.	p = 100 and q = 50
D.	p = 400 and q = 50
Answer» E.

Discussion

23.

A message is made up entirely of characters from the set X = {P,Q,R,S,T}. The table of probabilities for each of the characters is shown below:
Character Probability
P 0.22
Q 0.34
R 0.17
S 0.19
T 0.08
Total 1.00

If a message of 100 characters over X is encoded using Huffman coding, then the expected length of the encoded message in bits is ________.

A.

125

B.

225

C.

525

D.

121

Answer» C. 525

Discussion

24.	In a token ring network, the transmission speed is 10⁷ bps and the propagation speed is 200 m/ms. The 1-bit delay in this network is equivalent to
A.	500 m of cable
B.	200 m of cable
C.	20 m of cable
D.	50 m of cable
Answer» D. 50 m of cable

Discussion

25.	Consider a source computer (S) transmitting a file of size 106 bit to a destination computer (D) over a network of two routers (R₁ and R₂) and three links (L₁ , L₂ and L₃ ). L₁ connects S to R₁ ; L₂ connects R₁ to R₂ and L₃ connects R₂ to D. Let each link be of length 100 km. Assume signals travel over each link at a speed of 10⁸ m/s. Assume that the link bandwidth on each link is 1 Mbit/s. Let the file be broken down into 1000 packets each of size 1000 bits. Find the total sum of transmission and propagation delays in transmitting the file from S to D?
A.	1005 ms
B.	1010 ms
C.	3000 ms
D.	3003 ms
Answer» B. 1010 ms

Discussion

26.	Consider a 128 10³ bits/second satellite communication link with one way propagation delay of 150 milliseconds. Selective retransmission (repeat) protocol is used on this link to send data with a frame size of 1 kilobyte. Neglect the transmission time of acknowledgement. The minimum number of bits required for the sequence number field to achieve 100% utilization is ________ .
A.	10
B.	8
C.	4
D.	12
Answer» D. 12

Discussion

27.	A computer network uses polynomials over GF(2) for error checking with 8 bits as information bits and uses x ³ + x + 1 as the generator polynomial to generate the check bits. In this network, the message 01011011 is transmitted as
A.	01011011010
B.	01011011011
C.	01011011101
D.	01011011100
Answer» D. 01011011100

Discussion

28.	The values of parameters for the Stop-and-Wait ARQ protocol are as given below : Bit rate of the transmission channel = 1 Mbps. Propagation delay from sender to receiver = 0.75 ms. Time to process a frame = 0.25 ms. Number of bytes in the information frame = 1980. Number of bytes in the acknowledge frame = 20. Number of overhead bytes in the information frame = 20. Assume that there are no transmission errors. Then, the transmission efficiency (expressed in percentage) of the Stop-and-Wait ARQ protocol for the above parameters is _______ (correct to 2 decimal places).
A.	66.33%
B.	89.33%
C.	39.33%
D.	59.33%
Answer» C. 39.33%

Discussion

29.	Consider socket API on a Linux machine that supports connected UDP sockets. A connected UDP socket is a UDP socket on which connect function has already been called. Which of the following statements is/are CORRECT? I. A connected UDP socket can be used to communicate with multiple peers simultaneously. II. A process can successfully call connect function again for an already connected UDP socket.
A.	I only
B.	II only
C.	Both I and II
D.	Neither I nor II
Answer» C. Both I and II

Discussion

30.	Two hosts are connected via a packet switch with 10⁷ bits per second links. Each link has a propagation delay of 20 microseconds. The switch begins forwarding a packet 35 microseconds after it receives the same. If 10000 bits of data are to be transmitted between the two hosts using a packet size of 5000 bits, the time elapsed between the transmission of the first bit of data and the reception of the last bit of the data in microseconds is __________.
A.	175
B.	75
C.	100
D.	125
Answer» B. 75

Discussion

31.	A link has a transmission speed of 10⁶ bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgement has negligible transmission delay, and that its propagation delay is the same as the data propagation delay. Also assume that the processing delays at nodes are negligible. The efficiency of the stop-and-wait protocol in this setup is exactly 25%. The value of the oneway propagation delay(in milliseconds) is _______.
A.	10ms
B.	12 ms
C.	15ms
D.	2 ms
Answer» C. 15ms

Discussion

32.	For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE?
A.	II, and III
B.	I and III only
C.	II and III only
D.	II only
Answer» C. II and III only

Discussion

33.	For a host machine that uses the token bucket algorithm for congestion control, the token bucket has a capacity of 1 megabyte and the maximum output rate is 20 megabytes per second. Tokens arrive at a rate to sustain output at a rate of 10 megabytes per second. The token bucket is currently full and the machine needs to send 12 mega bytes of data. The minimum time required to transmit the data is _______ seconds.
A.	1.1 seconds.
B.	1.2 seconds.
C.	1.3 seconds.
D.	1.4 seconds.
Answer» C. 1.3 seconds.

Discussion

34.	Assuming that the packets are correctly delivered, how many bytes, including headers, are delivered to the IP layer at the destination for one application message, in the best case? Consider only data packets.
A.	200
B.	220
C.	240
D.	260
Answer» E.

Discussion

35.	What is the rate at which application data is transferred to host H
A.	325.5 kbps
B.	354.5 kbps
C.	409.6 kbps
D.	512.0 kbps
Answer» C. 409.6 kbps

Discussion

36.	Station A uses 32 byte packets to transmit messages to Station B using a sliding window protocol. The round trip delay between A and B is 80 ms and the bottleneck bandwidth on the path between A and B is 12 kbps. What is the optimal window size that A should use?
A.	20
B.	40
C.	160
D.	320
Answer» C. 160

Discussion

37.	The distance between two stations M and N is L km. All frames are K bits long. The propagation delay per kilometer is t s. Let R b/s be the channel capacity. Assuming that processing delay is negligible, the minimum number of bits for the sequence number field in a frame for maximum utilization, when the sliding window protocol is used, is
A.	<table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td rowspan="2">log<sub>2</sub></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2LTR + 2K</center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td style="text-align: center;">K</td></tr></table>
B.	<table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td rowspan="2">log<sub>2</sub></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2LTR</center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td style="text-align: center;">K</td></tr></table>
C.	<table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td rowspan="2">log<sub>2</sub></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2LTR + K</center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td style="text-align: center;">K</td></tr></table>
D.	<table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td rowspan="2">log<sub>2</sub></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2LTR + K</center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td style="text-align: center;">2K</td></tr></table>
Answer» D. <table><tr><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td rowspan="2">log<sub>2</sub></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2LTR + K</center></td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td style="text-align: center;">2K</td></tr></table>

Discussion

38.	Consider an instance of TCP s Additive Increase Multiplicative Decrease (AIMD) algorithm where the Window size at the start of the slow phase is 2 MSS and the threshold at the start of the first transmission is 8 MSS. Assume that a timeout occurs during the fifth transmission. Find the congestion Window size at the end of the tenth transmission.
A.	8 MSS
B.	14 MSS
C.	7 MSS
D.	12 MASS
Answer» D. 12 MASS

Discussion

39.	A sender S sends a message m to receiver R. which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place.
A.	(I) and (II) only
B.	(I) only
C.	(II) only
D.	(II) and (III) only
Answer» C. (II) only

Discussion

40.	Which of the following are used to generate a message digest by the network security protocols?
A.	(P) and (R) only
B.	(Q) and (R) only
C.	(Q) and (S) only
D.	(R) and (S) only
Answer» D. (R) and (S) only

Discussion

41.	In the RSA public key cryptosystem, the private and public keys are (e, n) and (d, n) respectively, where n = p*q and p and q are large primes. Besides, n is public and p and q are private. Let M be an integer such that 0 < M < n and (n) = (p 1) (q 1). Now consider the following equations.
A.	1 and 2
B.	1 and 3
C.	2 and 4
D.	3 and 4
Answer» C. 2 and 4

Discussion

42.	Using public key cryptography, X adds a digital signature to message M, encrypts < M, > and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations?
A.	Encryption: X s private key followed by Y s private key; Decryption: X s public key followed by Y s private key
B.	Encryption: X s private key followed by Y s public key; Decryption: X s public key followed by Y s private key
C.	Encryption: X s public key followed by Y s private key; Decryption: Y s public key followed by X s private key
D.	Encryption: X s private key followed by Y s public key; Decryption: Y s private key followed by X s public key
Answer» E.

Discussion

43.	A 2 km long broadcast LAN has 10
A.	50 bytes
B.	100 bytes
C.	200 bytes
D.	None of these
Answer» E.

Discussion

44.	In a network of LANs connected by bridges, packets are sent from one LAN to another through intermediate bridges. Since, more than one path may exist between two LANs, packets may have to be routed through multiple bridges. Why is the spanning tree algorithm used for bridge-routing?
A.	For shortest path routing between LANs
B.	For avoiding loops in the routing paths
C.	For fault tolerance
D.	For minimizing collisions
Answer» C. For fault tolerance

Discussion

45.	Consider the correct spanning tree for the previous question. Let host H
A.	<img src="http://images.interviewmania.com/wp-content/uploads/2019/11/as-36.jpg">
B.	<img src="http://images.interviewmania.com/wp-content/uploads/2019/11/as-37.jpg">
C.	<img src="http://images.interviewmania.com/wp-content/uploads/2019/11/as-38.jpg">
D.	<img src="http://images.interviewmania.com/wp-content/uploads/2019/11/as-39.jpg">
Answer» B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/11/as-37.jpg">

Discussion

46.	Consider a network connecting two systems located 8000 kilometers apart. The bandwidth of the network is 500 10
A.	8
B.	4
C.	2
D.	0
Answer» B. 4

Discussion

47.	Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (10
A.	8000
B.	10000
C.	16000
D.	20000
Answer» E.

Discussion

48.	Consider a LAN with four nodes S
A.	10.4404
B.	1.4404
C.	0.4404
D.	None of these
Answer» D. None of these

Discussion

49.	A network has a data transmission bandwidth of 20 10
A.	200 bytes
B.	100 bytes
C.	500 bytes
D.	1000 bytes
Answer» B. 100 bytes

Discussion

50.	Suppose that everyone in a group of N people wants to communicate secretly with the N-1 others using symmetric key cryptographic system. The communication between any two persons should not be decodable by the others in the group. The number of keys required in the system as a whole to satisfy the confidentiality requirement is
A.	2N
B.	N(N - 1)
C.	N(N - 1)/2
D.	(N - 1)2
Answer» D. (N - 1)2

Discussion

Explore topic-wise MCQs in Computer Networks.

Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (108 bits per second) over a 1 km (kilometer) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/ sec) in the cable?

A network has a data transmission bandwidth of 20 106 bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 micro seconds. The minimum size of a frame in the network is ________ bytes.

For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE? I. At least three non-overlapping channels are available for transmissions. II. The RTS-CTS mechanism is used for collision detection. III. Unicast frames are ACKed.

Which of the following are used to generate a message digest by the network security protocols? (P) RSA (Q) SHA-1 (R) DES (S) MD5

A 2 km long broadcast LAN has 107 bps bandwidth and uses CSMA/CD. The signal travels along the wire at 2 108 m/s. What is the minimum packet size that can be used on this network?

The message 11001001 is to be transmitted using the CRC polynomial x3 + 1 to protect it from errors. The message that should be transmitted is

Consider the following statements I. TCP connections are full duplex II. TCP has no option for selective acknowledgment III. TCP connections are message streams

What is the rate at which application data is transferred to host HC ? Ignore errors, acknowledgements, and other overheads.

Which of the following is/are example(s) of stateful application layer protocols? (i) HTTP (ii) FTP (iii) TCP (iv) POP3

Consider a binary code that consists of only four valid codewords as given below : 00000,01011,10101,11110 Let the minimum Hamming distance of the code be p and the maximum number of erroneous bits that can be corrected by the code be q. Then the values of p and q are

In a token ring network, the transmission speed is 107 bps and the propagation speed is 200 m/ms. The 1-bit delay in this network is equivalent to

A computer network uses polynomials over GF(2) for error checking with 8 bits as information bits and uses x 3 + x + 1 as the generator polynomial to generate the check bits. In this network, the message 01011011 is transmitted as

For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE?

Assuming that the packets are correctly delivered, how many bytes, including headers, are delivered to the IP layer at the destination for one application message, in the best case? Consider only data packets.

What is the rate at which application data is transferred to host H

Station A uses 32 byte packets to transmit messages to Station B using a sliding window protocol. The round trip delay between A and B is 80 ms and the bottleneck bandwidth on the path between A and B is 12 kbps. What is the optimal window size that A should use?

A sender S sends a message m to receiver R. which is digitally signed by S with its private key. In this scenario, one or more of the following security violations can take place.

Which of the following are used to generate a message digest by the network security protocols?

In the RSA public key cryptosystem, the private and public keys are (e, n) and (d, n) respectively, where n = p*q and p and q are large primes. Besides, n is public and p and q are private. Let M be an integer such that 0 < M < n and (n) = (p 1) (q 1). Now consider the following equations.

Using public key cryptography, X adds a digital signature to message M, encrypts < M, > and sends it to Y, where it is decrypted. Which one of the following sequences of keys is used for the operations?

A 2 km long broadcast LAN has 10

In a network of LANs connected by bridges, packets are sent from one LAN to another through intermediate bridges. Since, more than one path may exist between two LANs, packets may have to be routed through multiple bridges. Why is the spanning tree algorithm used for bridge-routing?

Consider the correct spanning tree for the previous question. Let host H

Consider a network connecting two systems located 8000 kilometers apart. The bandwidth of the network is 500 10

Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (10

Consider a LAN with four nodes S

A network has a data transmission bandwidth of 20 10

Consider a CSMA/CD network that transmits data at a rate of 100 Mbps (10⁸ bits per second) over a 1 km (kilometer) cable with no repeaters. If the minimum frame size required for this network is 1250 bytes, what is the signal speed (km/ sec) in the cable?

A network has a data transmission bandwidth of 20 10⁶ bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 micro seconds. The minimum size of a frame in the network is ________ bytes.

For the IEEE 802.11 MAC protocol for wireless communication, which of the following statements is/are TRUE?
I. At least three non-overlapping channels are available for transmissions.
II. The RTS-CTS mechanism is used for collision detection.
III. Unicast frames are ACKed.

Which of the following are used to generate a message digest by the network security protocols?
(P) RSA (Q) SHA-1 (R) DES (S) MD5

A 2 km long broadcast LAN has 10⁷ bps bandwidth and uses CSMA/CD. The signal travels along the wire at 2 10⁸ m/s. What is the minimum packet size that can be used on this network?

The message 11001001 is to be transmitted using the CRC polynomial x³ + 1 to protect it from errors. The message that should be transmitted is

Consider the following statements
I. TCP connections are full duplex
II. TCP has no option for selective acknowledgment
III. TCP connections are message streams

What is the rate at which application data is transferred to host H_C ? Ignore errors, acknowledgements, and other overheads.

Which of the following is/are example(s) of stateful application layer protocols?
(i) HTTP (ii) FTP (iii) TCP (iv) POP3

Consider a binary code that consists of only four valid codewords as given below :
00000,01011,10101,11110
Let the minimum Hamming distance of the code be p and the maximum number of erroneous bits that can be corrected by the code be q. Then the values of p and q are

In a token ring network, the transmission speed is 10⁷ bps and the propagation speed is 200 m/ms. The 1-bit delay in this network is equivalent to

A computer network uses polynomials over GF(2) for error checking with 8 bits as information bits and uses x ³ + x + 1 as the generator polynomial to generate the check bits. In this network, the message 01011011 is transmitted as