GATE-CS-2015 (Set 1)

Question 21

Which one of the following is True at any valid state in shift-reduce parsing?

• Viable prefixes appear only at the bottom of the stack and not inside
• Viable prefixes appear only at the top of the stack and not inside
• The stack contains only a set of viable prefixes
• The stack never contains viable prefixes

Question 22

Which one of the following is not equivalent to p←→q

• A
• B
• C
• D

Question 23

Which of following statements is/are False?

1. XML overcomes the limitations in HTML 
   to support a structured way of organizing content.

2. XML specification is not case sensitive while 
   HTML specification is case sensitive.

3. XML supports user defined tags while HTML
   uses pre-defined tags.

4. XML tags need not be closed while HTML 
   tags must be closed.

• 2 only
• 1 only
• 2 and 4 only
• 3 and 4 only

Question 24

For a set A, the power set of A is denoted by 2^A. If A = {5, {6}, {7}}, which of the following options are True.

• I and III only
• II and III only
• I, II and III only
• I, II and IV only

Question 25

In one of the pairs of protocols given below, both the protocols can use multiple TCP connections between the same client and the server. Which one is that?

• HTTP, FTP
• HTTP, TELNET
• FTP, SMTP
• HTTP, SMTP

Question 26

In the LU decomposition of the matrix

| 2  2 |
| 4  9 |

, if the diagonal elements of U are both 1, then the lower diagonal entry l₂₂ of L is

• 4
• 5
• 6
• 7

Question 27

Suppose two hosts use a TCP connection to transfer a large file. Which of the following statements is/are False with respect to the TCP connection?

1. If the sequence number of a segment is m, then the sequence 
   number of the subsequent segment is always m+1.
2. If the estimated round trip time at any given point of time
   is t sec, the value of the retransmission timeout is always
   set to greater than or equal to t sec.
3. The size of the advertised window never changes during the 
   course of the TCP connection.
4. The number of unacknowledged bytes at the sender is always 
   less than or equal to the advertised window 

• 3 only
• 1 and 3 only
• 1 and 4 only
• 2 and 4 only

Question 28

Consider a 4 bit Johnson counter with an initial value of 0000. The counting sequence of this counter is:

• 0, 1, 3, 7, 15, 14, 12, 8, 0

• 0, 1, 3, 5, 7, 9, 11, 13, 15, 0

• 0, 2, 4, 6, 8, 10, 12, 14, 0

• 0, 8, 12, 14, 15, 7, 3, 1, 0

Question 29

Which one of the following fields of an IP header is NOT modified by a typical IP router?

• Checksum

• Source address

• Time to Live (TTL)

• Length

Question 30

What are the worst-case complexities of insertion and deletion of a key in a binary search tree?

• Θ(logn) for both insertion and deletion
• Θ(n) for both insertion and deletion
• Θ(n) for insertion and Θ(logn) for deletion
• Θ(logn) for insertion and Θ(n) for deletion