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76. Consider the following schedule S of transactions Ti and T2:
Ti T2
Read (A)
A = A - iO
Read (A)
Temp 0.2*A
Write (A)
Read (B)
Write (A)
Read (B)
B=B+iO
Write (B)
B = B+Te m p
Write (B)
Which of the following is TRUE about the schedule 5?
(A) S is serializable only as Ti, T2
(B) S is serializable only as T2, Ti
(C) S is serializable both as Ti, T2 and T2, Ti
(D) S is serializable either as Ti or as T2
77. Consider two tables in a relational database with columns and rows as follows:
Table: Student
Roll_no Name Dept_id
1 ABC 1
2 DEF 1
3 GHI 2
4 JKL 3
Table: Department
Dept_id Dept_Name
1 A
2 B
3 C
Roll_no is the primary key of the Student table, Dept_id is the primary key of the
Department table and Studetn.Dept_id is a foreign key from
Department. Dept_id.
What will happen if we try to execute the following two SQL statements?
(i) update Student set Dept_id \= Null where Roll_no =1
(ii) update Department set Dept_id = Null where Dept_id =1
(A) Both (i) and (ii) will fail
(B) (i) will fail but (ii) will succeed
(C) (i) will succeed but (ii) will fail
(D) Both (i) and (ii) will succeed
78. Consider a table T in a relational database with a key field K.
A B-tree of order p is used as an access structure on K, where p denotes
the maximum number of tree pointers in a B-tree index node. Assume that
K is 10 bytes long; disk block size is 512 bytes; each data pointer
D is 8 bytes long and each block pointer PB is 5 bytes long. In order for
each B-tree node to fit in a single disk block, the maximum value of p is:
(A) 20
(B) 22
(C) 23
(D) 32
79. In a data link protocol, the frame delimiter flag is given by 0111.
Assuming that bit stuffing is employed, the transmitter sends the data
sequence 01110110 as
(A) 01101011
(B) 011010110
(C) 011101100
(D)0110101100
80. In a sliding window ARQ scheme, the transmitter�s window size is N and
the receiver�s window size is M. The minimum number of distinct sequence
numbers required to ensure correct operation of the ARQ scheme is:
(A) min(M,N)
(B) max(M,N)
(C) M+N
(D) MN
81. Consider a 10 Mbps token ring LAN with a ring latency of 400ps.
A host that needs to transmit seizes the token. Then it sends a frame
of 1000 bytes, removes the frame after it has circulated all around
the ring, and finally releases the token. This process is repeated for
every frame. Assuming that only a single host wishes to transmit,
the effective data rate is:
(A) 1 Mbps
(B) 2 Mbps
(C) 5 Mbps
(D)6 Mbps
82. A 25 Kbps satellite link has a propagation delay of 400 ms.
The transmitter employs the �go back n ARQ� scheme with n set to 10.
Assuming that each frame is 100 bytes long,
what is the maximum data rate possible?
(A) 5 Kbps
(B) 10 Kbps
(C) 15 Kbps
(D)20 Kbps
83. Consider a parity check code with three data bits and four parity check bits.
Three of the code words are 0101011, 1001101 and 1110001.
Which of the following are also code words?
I. 0010111 II. 0110110 III. 1011010 IV. 0111010
(A) I and III
(B) I, II and III
(C) II and IV
(D) I, II, III and IV
84. Consider a simplified time slotted MAC protocol, where each host always has
data to send and transmits with probability p=0.2 in every slot. There is no back
off and one frame can be transmitted in one slot. If more than one host transmits
in the same slot, then the transmissions are unsuccessful due to collision.
What is the maximum number of hosts which this protocol can support,
if each host has to be provided a minimum throughput of 0.16 frames per time slot?
(A) 1
(B) 2
(C) 3
(D)4
85. In the TCP/IP protocol suite, which one of the following is NOT part of the IP
header?
(A) Fragment offset
(B) Source IP address
(C) Destination IP address
(D) Destination port number
86. A TCP message consisting of 2100 bytes is passed to IP for delivery
across two networks. the first network can carry a maximum payload of
1200 bytes per frame and the second network can carry a maximum payload
of 400 bytes per frame, excluding network overhead. Assume that IP overhead
per packet is 20 bytes. What is the total IP overhead in
the second network for this transmission?
(A) 40 bytes
(B) 80 bytes
(C) 120 bytes
(D) 160 bytes
87. Suppose that the maximum transmit window size for a TCP connection
is 12000 bytes. Each packet consists of 2000 bytes. At some point of time,
the connection is is slow-start phase with a current transmit window of 4000 bytes.
Subsequently, the transmitter receives two acknowledgements. Assume that no
packets are lost and there are no time-outs. What is the maximum possible
value of the current transmit window?
(A) 4000 bytes
(B) 8000 bytes
(C) 10000 bytes
(D) 12000 bytes
88. Consider an XML file called intro.xml and a document type definition (DTD)
file intro.dtd as follows:
intro.xml
<?xml version = �1.0�?>
<!DOCTYPE myMessage SYSTEM �intro.dtd�>
<myMessage>
<message? Welcome to XML</message>
</myMessage>
intro.dtd
<!ELEMENTmyMessage (message)>
<!ELEMENT message (#PCDATA)>
A validating parser will classify intro.xml as
(A) Well formed and validated
(B) Well formed but not validated
(C) Validated but not well formed
(D) Neither validated not well formed
89. Given below are several usages of the anchor tag in HTML.
I. <A HREF=http://www.gate.ac.in/HTML/BASIC/testpage.html >TestMe</A>
II. <A HREF =�/BASIC/testpage. html�>Test Me</A>
III. <A HREF=�testpage.html�>Test ME</A>
IV. <A HREF =�testpage. html#test�>Test Me</A>
Which of the above are valid?
(A) I and II only
(B) I and III only
(C) I, II and III only
(D) I, II, III and IV
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