Question 1
Suppose two hosts are connected by a point-to-point link and they are configured to use Stop-and-Wait protocol for reliable data transfer. Identify in which one of the following scenarios, the utilization of the link is the lowest.
 A Longer link length and lower transmission rate B Longer link length and higher transmission rate C Shorter link length and lower transmission rate D Shorter link length and higher transmission rate
GATE CSE 2023   Computer Network
Question 1 Explanation:
 Question 2
Consider a 100 Mbps link between an earth station (sender) and a satellite (receiver) at an altitude of 2100 km. The signal propagates at a speed of $3 \times 10^8$ m/s. The time taken (in milliseconds, rounded off to two decimal places) for the receiver to completely receive a packet of 1000 bytes transmitted by the sender is
 A 15.06 B 54.25 C 7.08 D 4.25
GATE CSE 2022   Computer Network
Question 2 Explanation:

 Question 3
Consider a network using the pure ALOHA medium access control protocol, where each frame is of length 1,000 bits. The channel transmission rate is 1 Mbps (=$10^6$ bits per second). The aggregate number of transmissions across all the nodes (including new frame transmissions and retransmitted frames due to collisions) is modelled as a Poisson process with a rate of 1,000 frames per second. Throughput is defined as the average number of frames successfully transmitted per second. The throughput of the network (rounded to the nearest integer) is ______________
 A 180 B 160 C 135 D 115
GATE CSE 2021 SET-2   Computer Network
Question 3 Explanation:
 Question 4
Consider the cyclic redundancy check (CRC) based error detecting scheme having the generator polynomial $X^3+X+1$. Suppose the message $m_4m_3m_2m_1m_0=11000$ is to be transmitted. Check bits $c_2c_1c_0$ are appended at the end of the message by the transmitter using the above CRC scheme. The transmitted bit string is denoted by $m_4m_3m_2m_1m_0c_2c_1c_0$. The value of the checkbit sequence $c_2c_1c_0$ is
 A 101 B 110 C 100 D 111
GATE CSE 2021 SET-2   Computer Network
Question 4 Explanation:
 Question 5
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 ($= 10^6$ 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 _____________
 A 82 B 51 C 44 D 65
GATE CSE 2021 SET-1   Computer Network
Question 5 Explanation:

There are 5 questions to complete.

### 14 thoughts on “Data Link Layer”

1. Question number 37, it suld be 46.4 microseconds not miliseconds. Please correct it

• Thank you for your suggestion. We have updated it.

2. question 10: options should be in Bps not bps

3. Sorry question no:42

• Thank you for your suggestion. We have updated it.

4. For the question no: 40 The answer have to be 25%. Please do correct it.

• Thank you MOUNIKA DASA,

5. In Qestion no 13 data is missing
propagation speed of link is ( 2×10^8 meter per second ) not millisecond please correct it.

• Thank You devendra,
We have updated the question.

6. Ques number 33
correct answer is 320bytes, which is not given in option.

7. Please correct the Answer of 83 ques number in dll it should be “D”512 instead of 464

8. question no1 the answer should be (B)

• 9. 