Consider a 128×10 3 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 ___________
1.2
2.4
3.6
4.8
Host A is sending data to host B over a full duplex link. A and B are using the sliding window protocol for flow control. The send and receive window sizes are 5 packets each. Data packets (sent only from A to B) are all 1000 bytes long and the transmission time for such a packet is 50 µs. Acknowledgement packets (sent only from B to A) are very small and require negligible transmission time. The propagation delay over the link is 200 us. What is the maximum achievable throughput in this communication?
1.7.69 × 10^6 bytes per second
2.11.11 × 10^6 bytes per second
3.12.33 × 10^6 bytes per second
4.15.00 × 10^6 bytes per second
Identify the correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket API.
1.listen, accept, bind recv
2.bind, listen, accept, recv
3.bind, accept, listen, recv
4.accept, listen, bind, recv
In a token ring network the transmission speed is 10^7 bps and the propagation speed is 200 metres/micro second. The 1-bit delay in this network is equivalent to:
1.500 metres of cable
2.200 metres of cable
3.20 metres of cable
4.50 metres of cable
Match the following: (P) SMTP (1) Application layer (Q) BGP (2) Transport layer (R) TCP (3) Data link layer (S) PPP (4) Network layer (5) Physical layer
1.P – 2 Q – 1 R – 3 S – 5
2.P – 1 Q – 4 R – 2 S – 3
3.P – 1 Q – 4 R – 2 S – 5
4.P – 2 Q – 4 R – 1 S – 3
Suppose that the stop-and-wait protocol is used on a link with a bit rate of 64 kilobits per second and 20 milliseconds propagation delay. Assume that the transmission time for the acknowledgment and the processing time at nodes are negligible. Then the minimum frame size in bytes to achieve a link utilization of at least 50% is _________.
1.160
2.320
3.640
4.220
The message 11001001 is to be transmitted using the CRC polynomial x^3 + 1 to protect it from errors. The message that should be transmitted is:
1.11001001000
2.11001001011
3. 11001010
4.110010010011
There are n stations in a slotted LAN. Each station attempts to transmit with a probability p in each time slot. What is the probability that ONLY one station transmits in a given time slot?
1.(1-p)^(n-1)
2.np(1-p)^(n-1)
3.p(1-p)^(n-1)
4.1-(1-p)^(n-1)
Which of the following is not true about User Datagram Protocol in transport layer?
1.Works well in unidirectional communication, suitable for broadcast information
2.It does three way handshake before sending datagrams
3.It provides datagrams, suitable for modeling other protocols such as in IP tunneling or Remote Procedure Call and the Network File System
4.The lack of retransmission delays makes it suitable for real-time applications
Which of the following statements is TRUE about CSMA/CD ?
1.IEEE 802.11 wireless LAN runs CSMA/CD protocol
2.Ethernet is not based on CSMA/CD protocol
3.CSMA/CD is not suitable for a high propagation delay network like satellite network
4.There is no contention in a CSMA/CD network
Which one of the following is not a client server application?
1. Internet chat
2.Web browsing
3.E-mail
4.ping
A 2 km long broadcast LAN has 10^7 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?
1.50 bytes
2.100 bytes
3.200 bytes
4.None of these
A and B are the only two stations on an Ethernet. Each has a steady queue of frames to send. Both A and B attempt to transmit a frame, collide, and A wins the first backoff race. At the end of this successful transmission by A, both A and B attempt to transmit and collide. The probability that A wins the second backoff race is:
1.0.5
2.0.625
3.0.75
4.1.0
A bit-stuffing based framing protocol uses an 8-bit delimiter pattern of 01111110. If the output bit-string after stuffing is 01111100101, then the input bit-string is
1.0111110100
2.0111110101
3.0111111101
4.0111111111
A channel has a bit rate of 4 kbps and one-way propagation delay of 20 ms. The channel uses stop and wait protocol. The transmission time of the acknowledgement frame is negligible. To get a channel efficiency of at least 50%, the minimum frame size should be
1. 80 bytes
2.80 bits
3.160 bytes
4. 160 bits
A graphical HTML browser resident at a network client machine Q accesses a static HTML webpage from a HTTP server S. The static HTML page has exactly one static embedded image which is also at S. Assuming no caching, which one of the following is correct about the HTML webpage loading (including the embedded image)?
1.Q needs to send at least 2 HTTP requests to S, each necessarily in a separate TCP connection to server S
2.Q needs to send at least 2 HTTP requests to S, but a single TCP connection to server S is sufficient
3.A single HTTP request from Q to S is sufficient, and a single TCP connection between Q and S is necessary for this
4.A single HTTP request from Q to S is sufficient, and this is possible without any TCP connection between Q and S
A link has a transmission speed of 10^6 bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgment 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 one-way propagation delay (in milliseconds) is ___________.
1.4
2.8
3.12
4.16
A network has a data transmission bandwidth of 20 × 10 6 bits per second. It uses CSMA/CD in the MAC layer. The maximum signal propagation time from one node to another node is 40 microseconds. The minimum size of a frame in the network is _________ bytes.
1.200
2.250
3.400
4.1200
A network with CSMA/CD protocol in the MAC layer is running at 1 Gbps over a 1 km cable with no repeaters. The signal speed in the cable is 2 x 108 m/sec. The minimum frame size for this network should be
1.10000 bits
2.10000 bytes
3.5000 bIts
4.5000 bytes
A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 Kbps (1Kbps = 1000 bits/second). Size of an acknowledgement is 100 bytes and the transmission rate at the receiver is 8 Kbps. The one-way propagation delay is 100 milliseconds. Assuming no frame is lost, the sender throughput is __________ bytes/second.
1.2500
2.2000
3.1500
4.500
Assume that the bandwidth for a TCP connection is 1048560 bits/sec. Let α be the value of RTT in milliseconds (rounded off to the nearest integer) after which the TCP window scale option is needed. Let β be the maximum possible window size with window scale option. Then the values of α and β are
1.63 milliseconds 65535 × 21^4
2.63 milliseconds 65535 × 2^16
3.500 milliseconds 65535 × 2^14
4.500 milliseconds 65535 × 2^16
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?
1.1500
2.1700
3.1800
4.2000
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 probabilities 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 _________.
1.0.462
2.0.711
3.0.5
4.0.652
Consider a network connecting two systems located 8000 kilometers apart. The bandwidth of the network is 500 × 10^6 bits per second. The propagation speed of the media is 4 × 10^6 meters per second. It is needed to design a Go-Back-N sliding window protocol for this network. The average packet size is 10^7 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 he sequence number field has to be ________.
1.2
2.4
3.8
4.16
Consider a selective repeat sliding window protocol that uses a frame size of 1 KB to send data on a 1.5 Mbps link with a one-way latency of 50 msec. To achieve a link utilization of 60%, the minimum number of bits required to represent the sequence number field is ________.
1.3
2.4
3.5
4.6
Consider a TCP connection in a state where there are no outstanding ACKs. The sender sends two segments back to back. The sequence numbers of the first and second segments are 230 and 290 respectively. The first segment was lost, but the second segment was received correctly by the receiver. Let X be the amount of data carried in the first segment (in bytes), and Y be the ACK number sent by the receiver. The values of X and Y (in that order) are
1.60 and 290
2. 230 and 291
3. 60 and 231
4.60 and 230
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 × 10^8 m/s and the token transmission time is ignored. If each station is allowed to hold the token for 2 μsec, the minimum time for which the monitoring station should wait (in μsec)before assuming that the token is lost is _______.
1.28 to 30
2.20 to 22
3. 0 to 2
4. 31 to 33
Consider different activities related to email. m1: Send an email from a mail client to a mail server m2: Download an email from mailbox server to a mail client m3: Checking email in a web browser Which is the application level protocol used in each activity?
1.ml: HTTP m2: SMTP m3: POP
2.ml: SMTP m2: FTP m3: HTTP
3. ml: SMTP m2: POP m3: HTTP
4.ml: POP m2: SMTP m3: IMAP
Consider the following message M = 1010001101. The cyclic redundancy check (CRC) for this message using the divisor polynomial x^5 + x^4 + x^2 + 1 is :
1.01110
2.01011
3.10101
4.10110
Consider the following statements about the timeout value used in TCP. i. The timeout value is set to the RTT (Round Trip Time) measured during TCP connection establishment for the entire duration of the connection. ii. Appropriate RTT estimation algorithm is used to set the timeout value of a TCP connection. iii. Timeout value is set to twice the propagation delay from the sender to the receiver. Which of the following choices hold?
1.(i) is false, but (ii) and (iii) are true
2.(i) and (iii) are false, but (ii) is true
3.(i) and (ii) are false, but (iii) is true
4.(i), (ii) and (iii) are false
Consider the following statements. I. TCP connections are full duplex. II. TCP has no option for selective acknowledgment III. TCP connections are message streams.
1.Only I is correct
2.Only I and II are correct
3.Only II and III are correct
4. All of I, II and III are correct
Consider the following statements: I. telnet, ftp and http are application layer protocols. II.l EJB (Enterprise Java Beans) components can be deployed in a J2EE (Java2 Enterprise Edition) application server. III. If two languages conform to the Common Language Specification (CLS) of the Microsoft.NET framework, then a class defined in any one of them may be inherited in the other. Which statements are true?
1.l and II only
2.II and III only
3.l and III only
4.I, II and III
Determine the maximum length of the cable (in km) for transmitting data at a rate of 500 Mbps in an Ethernet LAN with frames of size 10,000 bits. Assume the signal speed in the cable to be 2,00,000 km/s.
1.1
2.2
3.2.5
4.5
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 megabytes of data. The minimum time required to transmit the data is _________________ seconds.
1.1.1
2.0.1
3. 2.1
4.2.0
Frames of 1000 bits are sent over a 10^6 bps duplex link between two hosts. The propagation time is 25ms. Frames are to be transmitted into this link to maximally pack them in transit (within the link). What is the minimum number of bits (i) that will be required to represent the sequence numbers distinctly? Assume that no time gap needs to be given between transmission of two frames.
1.i = 2
2.i = 3
3.i = 4
4.i = 5
How many 8-bit characters can be transmitted per second over a 9600 baud serial communication link using asynchronous mode of transmission with one start bit, eight data bits, two stop bits, and one parity bit ?
1.600
2.800
3.876
4.1200
How many bytes of data can be sent in 15 seconds over a serial link with baud rate of 9600 in asynchronous mode with odd parity and two stop bits in the frame?
1.10,000 bytes
2.12,000 bytes
3.15,000 bytes
4.27,000 bytes
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.
1.4,2,1,3
2.1,2,3,4
3.4,1,2,3 d.
4.2,4,1,3
In a TDM medium access control bus LAN, each station is assigned one time slot per cycle for transmission. Assume that the length of each time slot is the time to transmit 100 bits plus the end-to-end propagation delay. Assume a propagation speed of 2 x 10^8 m/sec. The length of the LAN is 1 km with a bandwidth of 10 Mbps. The maximum number of stations that can be allowed in the LAN so that the throughput of each station can be 2/3 Mbps is
1.3
2.5
3.10
4.20
In an Ethernet local area network, which one of the following statements is TRUE ?
1.A station stops to sense the channel once it starts transmitting a frame
2.The purpose of the jamming signal is to pad the frames that are smaller than the minimum frame size
3.A station continues to transmit the packet even after the collision is detected
4. The exponential backoff mechanism reduces the probability of collision on retransmissions
In Ethernet when Manchester encoding is used, the bit rate is:
1.Half the baud rate
2.Twice the baud rate
3.Same as the baud rate
4.None of the above
In serial data transmission, every byte of data is padded with a ‘0’ in the beginning and one or two ‘I’ s at the end of byte because
1.Receiver is to be synchronized for byte reception
2.Receiver recovers lost ‘0’ and ‘1’s from these padded bits
3.Padded bits are useful in parity computation
4.None of these
Let G(x) be the generator polynomial used for CRC checking. What is the condition that should be satisfied by G(x) to detect odd number of bits in error?
1.G(x) contains more than two terms
2.G(x) does not divide 1+x^k, for any k not exceeding the frame length
3.1+x is a factor of G(x)
4.G(x) has an odd number of terms
On a TCP connection, current congestion window size is Congestion Window = 4 KB. The window size advertised by the receiver is Advertise Window = 6 KB. The last byte sent by the sender is LastByteSent = 10240 and the last byte acknowledged by the receiver is LastByteAcked = 8192. The current window size at the sender is
1.2048 bytes
2.4096 bytes
3.6144 bytes
4.8192 bytes
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 milliseconds and the bottleneck bandwidth on the path between A and B is 128 kbps. What is the optimal window size that A should use?
1.20
2.40
3.160
4.320
Suppose the round trip propagation delay for a 10 Mbps Ethernet having 48-bit jamming signal is 46.4 ms. The minimum frame size is
1.94
2.416
3.464
4.512
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? 1. If the sequence number of a segment is m, then the sequence number of the subsequent segment is always m+1. 2. 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. 3. The size of the advertised window never changes during the course of the TCP connection. 4. The number of unacknowledged bytes at the sender is always less than or equal to the advertised window
1.3 only
2.1 and 3 only
3.1 and 4 only
4.2 and 4 only
Which of the following is/are example(s) of stateful application layer protocols? (i) HTTP (ii) FTP (iii) TCP (iv) POP3
1.(i) and (ii) only
2.(ii) and (iii) only
3.(ii) and (iv) only
4.(iv) only
Which of the following statements are TRUE? (S1) TCP handles both congestion and flow control (S2) UDP handles congestion but not flow control (S3) Fast retransmit deals with congestion but not flow control (S4) Slow start mechanism deals with both congestion and flow control
1.S1, S2 and S3 only
2. S1 and S3 only
3.S3 and S4 only
4.S1, S3 and S4 only
Which of the following statements is FALSE regarding a bridge?
1.Bridge is a layer 2 device
2. Bridge reduces collision domain
3.Bridge is used to connect two or more LAN segments
4.Bridge reduces broadcast domain
Which one of the following statements is FALSE ?
1.Packet switching leads to better utilization of bandwidth resources than circuit switching
2.Packet switching results in less variation in delay than circuit switching
3.Packet switching requires more per packet processing than circuit switching
4.Packet switching can lead to reordering unlike in circuit switching