GATE CSE year:2021 PYQs & Answers — Page 11

Questions 101–110 of 130. Imported answers require independent review unless marked reviewed.

An articulation point in a connected graph is a vertex such that removing the vertex and its incident edges disconnects the graph into two or more connected components. Let

be a DFS tree obtained by doing DFS in a connected undirected graph

. Which of the following options is/are correct?

Your answerSelect all correct options. You can choose more than one.

Root of

can never be an articulation point in

Root of

is an articulation point in

if and only if it has 2 or more children.

A leaf of

can be an articulation point in

is an articulation point in

such that

is an ancestor of

and

is a descendent of

, then all paths from

must pass through

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For a string

, we define

to be the reverse of

. For example, if

then

. Which of the following languages is/are context-free?

Your answerSelect all correct options. You can choose more than one.

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Consider the following Boolean expression.

Which of the following Boolean expressions is/are equivalent to

(complement of

Your answerSelect all correct options. You can choose more than one.

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Consider the following multi-threaded code segment (in a mix of C and pseudo-code), invoked by two processes P1 and P2, and each of the processes spawns two threads T1 and T2:

int x = 0; // global

Lock L1; // global

main() {

create a thread to execute foo(); // Thread T1

create a thread to execute foo(); // Thread T2

wait for the two threads to finish execution;

print (x);

}

foo() {

int y = 0;

Acquire L1;

x = x + 1;

y = y + 1;

Release L1;

print (y);

}

Which of the following statement(s) is/are correct?

Your answerSelect all correct options. You can choose more than one.

Both P1 and P2 will print the value of x as 2.

At least one of P1 and P2 will print the value of x as 4.

At least one of the threads will print the value of y as 2.

Both T1 and T2, in both the processes, will print the value of y as 1.

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A relation

is said to be circular if

and

together imply

. Which of the following options is/are correct?

Your answerSelect all correct options. You can choose more than one.

If a relation

is reflexive and symmetric, then

is an equivalence relation.

If a relation

is circular and symmetric, then

is an equivalence relation.

If a relation

is reflexive and circular, then

is an equivalence relation.

If a relation

is transitive and circular, then

is an equivalence relation.

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Consider a computer system with multiple shared resource types, with one instance per resource type. Each instance can be owned by only one process at a time. Owning and freeing of resources are done by holding a global lock (L). The following scheme is used to own a resource instance:

function OwnResource(Resource R) Acquire lock L // a global lock if R is available then Acquire R Release lock L else if R is owned by another process P then Terminate P, after releasing all resources owned by P Acquire R Restart P Release lock L end if end if end function

Which of the following choice(s) about the above scheme is/are correct?

Your answerSelect all correct options. You can choose more than one.

The scheme ensures that deadlocks will not occur.

The scheme may lead to live-lock.

The scheme may lead to starvation.

The scheme violates the mutual exclusion property.

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A TCP server application is programmed to listen on port number

on host

. A TCP client is connected to the TCP server over the network. Consider that while the TCP connection was active, the server machine

crashed and rebooted. Assume that the client does not use the TCP keepalive timer. Which of the following behaviors is/are possible?

Your answerSelect all correct options. You can choose more than one.

If the client was waiting to receive a packet, it may wait indefinitely.

The TCP server application on

can listen on

after reboot.

If the client sends a packet after the server reboot, it will receive a RST segment.

If the client sends a packet after the server reboot, it will receive a FIN segment.

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If the numerical value of a 2-byte signed integer on a little endian computer is 255 more than that on a big endian computer, which of the following choices represent(s) the unsigned integer on a little endian computer?

Your answerSelect all correct options. You can choose more than one.

0x665

0x001

0x423

0x100

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Consider two hosts

and

connected through a router

. The maximum transfer unit (MTU) value of the link between

and

is 1500 bytes, and between

and

is 820 bytes. A TCP segment of size 1400 bytes was transferred from

through

, with IP identification value as 0x1234. Assume that the IP header size is 20 bytes. Further, the packet is allowed to be fragmented, i.e., Don’t Fragment (DF) flag in the IP header is not set by

. Which of the following statements is/are correct?

Your answerSelect all correct options. You can choose more than one.

Two fragments are created at

and the IP datagram size carrying the second fragment is 620 bytes.

If the second fragment is lost,

will resend the fragment with the IP identification value 0x1234.

If the second fragment is lost,

is required to resend the whole TCP segment.

TCP destination port can be determined by analysing only the second fragment.

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Consider a computer network using the distance vector routing algorithm in its network layer. The partial topology of the network is as shown below.

Diagram for Computer Science and Information Technology question 45

The objective is to find the shortest-cost path from the router

to routers

and

. Assume that

does not initially know the shortest routes to

and

. Assume that

has three neighboring routers denoted as

, and

. During one iteration,

measures its distance to its neighbours

, and

as 3, 2, and 5, respectively. Router

gets routing vectors from its neighbours that indicate that the distance to router

from routers

, and

are 7, 6, and 5, respectively. The routing vector also indicates that the distance to router

from routers

, and

are 4, 6, and 8, respectively. Which of the following statement(s) is/are correct with respect to the new routing table of

, after update during this iteration?

Your answerSelect all correct options. You can choose more than one.

The distance from

will be stored as 10.

The distance from

will be stored as 7.

The next hop router for a packet from

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GATE CSE year:2021 PYQs

Question 41

Question 41

Question 42

Question 42

Question 43

Question 43

Question 44

Question 44

Question 45

Question 45