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WorksheetsCN MODEL EXAM -III PART-B
Total questions: 15
Worksheet time: 30mins
Name
Class
Date
1.
Suppose an IP packet has been fragmented. Then which of the following is a set of fragments?
a)
128, 56, 84, 42
b)
372, 408, 12, 56
c)
248, 72, 120, 18
d)
48, 88, 70, 52
2.
In stop and wait protocol , every 4th packet is lost.If 8 packets are being sent, Find number of packets ?
a)
10
b)
8
c)
9
d)
none of the above
3.
An IP router with a MTU of 1400 bytes (excludes header length) has received and IP datagram of size 4000 bytes with on IP header<br />of length 20 bytes. The value of offset field in the header of the third IP fragment generated by the router for this packet are_____
a)
250
b)
350
c)
340
d)
240
4.
An IP packet to be transmitted by Ethernet is 60 bytes long, including all its headers. If LLC is not in use, is padding needed in the Ethernet frame, and if so, how many<br />bytes?
a)
60
b)
20
c)
40
d)
no padding required
5.
A router has two full-duplex Ethernet interfaces each operating at 100 Mb/s. Ethernet frames are at least 84 bytes long (including the Preamble and the Inter-Packet-Gap). The maximum packet processing time at the router for wirespeed forwarding to be possible is (in microseconds)
a)
0.01
b)
3.36
c)
6.72
d)
8
6.
Every host in an IPv4 network has a 1−second resolution real-time clock with battery backup. Each host needs to generate up to 1000 unique identifiers per second. Assume that each host has a globally unique IPv4 address. Design a 50−bit globally unique ID for this purpose. After what period (in seconds) will the identifiers generated by a host wrap around?
a)
128
b)
64
c)
256
d)
512
7.
If the TCP round-trip time, RTT, is currently 30 msec and the following acknowledgements come in after 26, 32, and 24 msec, respectively, what is the new RTT estimate<br />using the Jacobson algorithm? Use α = 0.9.
a)
29.6
b)
19.6
c)
15.6
d)
29.7
8.
Consider a TCP connection between two machines (A and B) in an environment with 0% packet loss. Assume the round trip time (RTT) between the two machines is 4 [seconds], and the segment size is 3 [Kbytes]. The bandwidth of the connection is 500 [kbps]. What is the minimum possible TCP window size for which there will be no stalling?(We say a TCP connection experiences no stalling if the acknowledgments arrive back to the sender before the sliding window over the send buffer close to zero. I.e., TCP packets are continuously, back-to-back, sent out of the sender before the first ack arrives back.)
a)
84
b)
64
c)
55
d)
25
9.
Given a mask, M=255.255.255.248. How many subnet bits are required for given mask M?
a)
2
b)
3
c)
4
d)
5
10.
Repeaters function in
a)
Physical layer
b)
Data link layer
c)
Network layer
d)
Both (A) and (B)
11.
If the original size of data is 40 then after adding error detection redundancy bit the size of data length is
a)
26
b)
36
c)
46
d)
56
12.
Correct expression tor UDP user datagram length is
a)
length of UDP = length of IP- length of IP header's
b)
length of UDP= length of UDP-length of UDP header's
c)
length of UDP = length of IP+length of IP header's
d)
length of UDP = length of UDP+length of UDP header's
13.
In classless addressing, there are no classes but addresses are still granted in
a)
codes
b)
block
c)
IP
d)
Sizes
14.
Which multiple access technique is used by IEEE 802.11 standard for wireless LAN ?
a)
CDMA
b)
CSMA/CA
c)
ALOHA
d)
None of the mentioned
15.
What is the value of acknowledgement field in a segment
a)
Number of previous bytes to receive
b)
Total number of bytes to receive
c)
Number of next bytes to receive
d)
Sequence of zero's and one's
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