CN Data Link Layer

Question 101

How many characters per second (7 bits + 1 parity) can be transmitted over a 3200 bps line if the transfer is asynchronous ? (Assuming 1 start bit and 1 stop bit)

• 300
• 320
• 360
• 400

Question 102

What is the propagation time if the distance between the two points is 48,000 ? Assume the propagation speed to be 2.4 × 10⁸ meter/second in cable.

• 0.5 ms
  

• 20 ms
  

• 50ms
  

• 200ms
  

Question 103

_______ can detect burst error of length less than or equal to degree of the polynomial and detects burst errors that affect odd number of bits.

• Hamming Code

• CRC

• VRC

• None of the above

Question 104

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 128 kbps. What is the optimal window size that A should use?

• 20
• 40
• 160
• 320

Question 105

When and where RARP is used intentionally or effectively?

• At the time of network booting where no space to store IP address (or diskless network) for address resolution.

• In broadcasting to get IP address of Network.

• To get the access in private network whenever it is required.

• None of the above.

Question 106

The period of a signal is 100 ms. Its frequency is _________.

• 100³Hertz
• 10^-2KHz
• 10^-3KHz
• 10⁵ Hertz

Question 107

The dotted-decimal notation of the following IPV4 address in binary notation is _________. 10000001 00001011 00001011 11101111

• 111.56.45.239
• 129.11.10.238
• 129.11.11.239
• 111.56.11.239

Question 108

Consider the following two statements.

• S1: Destination MAC address of an ARP reply is a broadcast address.
• S2: Destination MAC address of an ARP request is a broadcast address.

Which one of the following choices is correct?

• Both S1 and S2 are true
• S1 is true and S2 is false
• S1 is false and S2 is true
• Both S1 and S2 are false

Question 109

Assume that a 12-bit Hamming codeword consisting of 8-bit data and 4 check bits is d₈d₇d₆d₅c₈d₄d₄d₃d₂c₄d₁c₂c₁, where the data bits and the check bits are given in the following tables: Which one of the following choices gives the correct values of x and y?

• x is 0 and y is 0
• x is 0 and y is 1
• x is 1 and y is 0
• x is 1 and y is 1

Question 110

Consider the sliding window flow-control protocol operating between a sender and a receiver over a full-duplex error-free link. Assume the following:

• The time taken for processing the data frame by the receiver is negligible.
• The time taken for processing the acknowledgement frame by the sender is negligible.
• The sender has infinite number of frames available for transmission.
• The size of the data frame is 2,000 bits and the size of the acknowledgement frame is 10 bits.
• The link data rate in each direction is 1 Mbps (= 10⁶ bits per second).
• One way propagation delay of the link is 100 milliseconds.

The minimum value of the sender\'s window size in terms of the number of frames, (rounded to the nearest integer) needed to achieve a link utilization of 50% is_____________.

• 51

• 50

• 25

• 52