GATE CS 2022

Question 31

Consider the routing table of an organization’s router shown below:

Which of the following prefixes in CIDR notation can be collectively used to correctly aggregate all of the subnets in the routing table? 

• 12.20.164.0/20 

• 12.20.164.0/22

• 12.20.164.0/21

• 12.20.168.0/22

Question 32

Consider the relational database with the following four schemas and their respective instances.

Student(sNo, sName, dNo) Dept(dNo, dName) 

Course(cNo, cName, dNo) Register(sNo, cNo)

SQL Query: 

SELECT * FROM Student AS S WHERE NOT EXIST 
 (SELECT cNo FROM Course WHERE dNo = “D01” 
      EXCEPT 
   SELECT cNo FROM Register WHERE sNo = S.sNo) 

The number of rows returned by the above SQL query is___________.

• 4

• 3

• 2

• 0

Question 33

Consider a network with three routers P, Q, R shown in the figure below. All the links have cost of unity

The routers exchange distance vector routing information and have converged on the routing tables, after which the link Q−R fails. Assume that P and Q send out routing updates at random times, each at the same average rate. The probability of a routing loop formation (rounded off to one decimal place) between P and Q, leading to count-to-infinity problem, is___________.

• 1

• 3

• 2

• 0

Question 34

Let G (V, E) be a directed graph, where V = {1, 2, 3, 4, 5} is the set of vertices and E is the set of directed edges, as defined by the following adjacency matrix A.

[Tex]A[i][j]= \left\{\begin{matrix} 1,& 1\leq j\leq i\leq 5 \\ 0,& otherwise \end{matrix}\right.[/Tex]

• 18

• 24

• 12

• 36

Question 35

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 3x10⁸ 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_________.

• 3.95

• 5.09

• 7.08

• 9.65

Question 36

Consider the data transfer using TCP over a 1 Gbps link. Assuming that the maximum segment lifetime (MSL) is set to 60 seconds, the minimum number of bits required for the sequence number field of the TCP header, to prevent the sequence number space from wrapping around during the MSL is____________.

• 27.8

• 48.0

• 33.0

• 35.0

Question 37

Consider two files systems A and B , that use contiguous allocation and linked allocation, respectively. A file of size 100 blocks is already stored in A and also in B. Now, consider inserting a new block in the middle of the file (between 50th and 51st block), whose data is already available in the memory. Assume that there are enough free blocks at the end of the file and that the file control blocks are already in memory. Let the number of disk accesses required to insert a block in the middle of the file in A and B are n_A and n_B respectively, then the value of n_A  + n_B is_________. 

• 189

• 236

• 153

• 323

Question 38

Consider a demand paging system with four-page frames (initially empty) and an LRU page replacement policy. For the following page reference string 7, 2,7,3, 2,5,3, 4,6,7,7,1,5,6,1 the page fault rate, defined as the ratio of number of page faults to the number of memory accesses (rounded off to one decimal place) is_________.

• 1.5

• 0.5

• 0.6

• 0.8

Question 39

Consider the following grammar along with translation rules

Here # and % are operators and id is a token that represents an integer and id. val represents the corresponding integer value. The set of non-terminals is {S, T, R, P} and a subscripted non-terminal indicates an instance of the non-terminal. Using this translation scheme, the computed value of S.val for root of the parse tree for the expression 20#10%5#8%2%2 is _____________. 

• 60

• 55

• 75

• 80

Question 40

Use the most appropriate words to fill the blanks.

The _________ is too high for it to be considered _________.

•  fair / fare

• faer / fair

• fare / fare 

• fare / fair