UGC NET Computer Science Computer Networks Previous Year Questions (PYQs) – Page 1 of 12
Study Stuff for MCA Examinations
Solution
Nyquist Sampling Theorem states:
Sampling frequency must be at least twice the maximum frequency present in the signal.
$ f_s \ge 2f_{max} $
Solution
Frequency:
$f=\frac{1}{T}=\frac{1}{0.1}=10\ Hz$
Now convert into kHz:
$10\ Hz=\frac{10}{1000}\ kHz=0.01\ kHz=10^{-2}\ kHz$
Solution
Rearrange the following sequence in the context of OSI Layers:
I. Transforming the raw bits in the form of frame for transmission
II. Transmission of raw bits over communication channel
III. Handling user interfaces
IV. Control and monitoring of subnet
V. Transmission data through connection oriented or connection less using datagrams
Choose the correct answer from the options given below:
Solution
Physical layer:
Transmission of raw bits over communication channel.
So, II comes first.
Data Link layer:
Transforms raw bits into frames.
So, I comes second.
Network layer:
Controls and monitors subnet.
So, IV comes third.
Transport layer:
Provides connection-oriented or connection-less data transmission.
So, V comes fourth.
Application layer:
Handles user interfaces.
So, III comes last.
Solution
In Round Robin scheduling, each process gets CPU for one time quantum.
Given:
Time quantum $=4$ ms
Number of processes $=20$
Maximum waiting time occurs for the last process in the ready queue.
Before the last process gets CPU, the other $19$ processes will execute.
So,
Maximum waiting time $=19 \times 4$
$=76$ ms
A TCP Server application is programmed to listen on port P on Host S. A TCP Client is connected to the TCP Server over the network. Considered that while TCP Connection is active the server is crashed and rebooted. Assume that the client does not use TCP keepalive timer. Which of the following behaviours is/are possible?
Statement I:
If client is waiting to receive a packet, it may wait indefinitely.
Statement II:
If the client sends a packet after the server reboot, it will receive the FIN segment.
In the light of the above statements, choose the correct answer from the options given below.
Solution
When the server crashes and reboots, the server loses the old TCP connection state.
Statement I:
If the client is only waiting to receive data and TCP keepalive timer is not used, then the client may not immediately know that the server has crashed.
So, the client may wait indefinitely.
Therefore, Statement I is true.
Statement II:
After reboot, if the client sends a packet for the old TCP connection, the server will not recognize that old connection.
In this case, the server sends a reset segment, that is $RST$, not a $FIN$ segment.
$FIN$ is used for normal connection termination.
$RST$ is used when the connection is invalid or not recognized.
Therefore, Statement II is false.
Find the number of addresses in each subnet.
Solution
Given block:
$130.56.0.0/16$
Total host bits:
$32-16=16$
Number of required subnets:
$1024=2^{10}$
So, $10$ bits are borrowed for subnetting.
Remaining host bits:
$16-10=6$
Number of addresses in each subnet:
$2^6=64$
Find the subnet prefix.
Solution
Given network block is:
$130.56.0.0/16$
So, the network prefix part is:
$130.56$
Find first and last addresses of First subnet.
Solution
$64$ addresses
So, first subnet starts from:
$130.56.0.0$
Since each subnet has $64$ addresses, the first subnet range is:
$130.56.0.0$ to $130.56.0.63$
Therefore, first address is:
$130.56.0.0$
Last address is:
$130.56.0.63$
Find subnet mask.
Solution
Original prefix is:
$/16$
Required subnets:
$1024=2^{10}$
So, new prefix length is:
$16+10=26$
Therefore, subnet prefix is:
$/26$
Subnet mask for $/26$ is:
$255.255.255.192$
UGC NET Computer Science
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UGC NET Computer Science
Online Test Series, Information About Examination,
Syllabus, Notification
and More.
View More
