# UGC NET Computer Science Solved Paper III December 2014 - Part 3

21.       Which of the following statements is not true ?
(A) MPI_Isend and MPI_Irecv are non-blocking message passing routines of MPI.
(B) MPI_Issend and MPI_Ibsend are non-blocking message passing routines of MPI.
(C) MPI_Send and MPI_Recv are non-blocking message passing routines of MPI.
(D) MPI_Ssend and MPI_Bsend are blocking message passing routines of MPI.
22.       The pushdown automation M = ({q0, q1, q2}, {a, b}, {0, 1}, d, q0, 0, {q0}) with
d (q0, a, 0) = {(q1, 10)}
d (q1, a, 1) = {(q1, 11)}
d (q1, b, 1) = {(q2, l)}
d (q2, b, 1) = {(q2, l)}
d (q2, l, 0) = {(q0, l)}
Accepts the language
(A) L = {an bm | n, m ≥ 0}           (B) L = {an bn | n ≥ 0}
(C) L = {an bm | n, m > 0}          (D) L = {an bn | n > 0}
23.       Given two languages :
L1 = {(ab)n ak | n > k, k ≥ 0}
L2 = {an bm | n ¹ m}
Using pumping lemma for regular language, it can be shown that
(A) L1 is regular and L2 is not regular.
(B) L1 is not regular and L2 is regular.
(C) L1 is regular and L2 is regular.
(D) L1 is not regular and L2 is not regular.
24.       Regular expression for the complement of language L = {an bm | n ≥ 4, m ≤ 3} is
(A) (a + b)* ba(a + b)*
(B) a* bbbbb*
(C) (l + a + aa + aaa)b* + (a + b)* ba(a + b)*
(D) None of the above
25.       For n devices in a network, .............. number of duplex-mode links are required for a mesh topology.
(A) n(n + 1)       (B) n (n – 1)
(C) n(n + 1)/2    (D) n(n – 1)/2
26.       How many characters per second (7 bits + 1 parity) can be transmitted over a 3200 bps line if the transfer is asynchronous ? (Assuming 1 start bit and 1 stop bit)
(A) 300               (B) 320
(C) 360             (D) 400
27.       Which of the following is not a field in TCP header ?
(A) Sequence number            (B) Fragment offset
(C) Checksum                          (D) Window size
28.       What is the propagation time if the distance between the two points is 48,000 ? Assume the propagation speed to be 2.4 × 108 metre/second in cable.
(A) 0.5 ms          (B) 20 ms
(C) 50 ms          (D) 200 ms
29.       .............. is a bit-oriented protocol for communication over point-to-point and multipoint links.
(A) Stop-and-wait        (B) HDLC
(C) Sliding window     (D) Go-back-N