List of top Computer Science and IT Engineering Questions on Computer Networks

It is necessary to design a link-layer protocol between two hosts that are directly
connected over a lossless link of length 3000 kilometers. Assume that the link
bandwidth is \(10^8\) bits per second and that the propagation delay in the link is 5
nanoseconds per meter. Every transmitted data byte is assigned a unique sequence
number.
Let 𝑁 be the minimum number of bits needed for the sequence number field in the
protocol header such that
i.
the sequence numbers do not wrap around before 60 seconds, and
ii.
the maximum utilization of the link is achieved.
The value of 𝑁 is ______. (answer in integer)

Consider the transmission of data bits 110001011 over a link that uses Cyclic
Redundancy Check (CRC) code for error detection. If the generator bit pattern is
given to be 1001, which one of the following options shows the remainder bit
pattern appended to the data bits before transmission?

Consider a file of size 4 million bytes being transferred between two hosts
connected via a path consisting of three consecutive links of bandwidth 2 Mbps,
500 kbps, and 1 Mbps, respectively. All processing delays and propagation delays
are negligible. Assume that there is no other background traffic over the path and
no other additional overhead to transfer the file.
Which one of the following is the total time (in seconds) to transfer the file?
Note: \(1\mathrm{M}=10^6\), \(1\mathrm{k}=10^3\)

Consider the implementation of sliding window protocol over a lossless link, with a
window size of 𝑊 frames, where each frame is of size 1000 bits (including header).
The bandwidth of the link is 100 kbps (1k = 103) and the one-way propagation delay
is 100 milliseconds. Assume that processing times at the sender and receiver are zero
and the transmission time of acknowledgements is also zero. Which one of the
following options gives the minimum size of 𝑊 (in number of frames) required to
achieve 100% link utilization?