Fragmentation PYQ QUIZ GATE CS

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Question 1

In an IPv4 datagram, the M bit is 0, the value of HLEN is 10, the value of total length is 400 and the fragment offset value is 300. The position of the datagram, the sequence numbers of the first and the last bytes of the payload, respectively are

  • Last fragment, 2400 and 2789

  • First fragment, 2400 and 2759

  • Last fragment, 2400 and 2759

  • Middle fragment, 300 and 689

Question 2

Consider two hosts P and Q connected through a router R. The maximum transfer unit (MTU) value of the link between P and R is 1500 bytes, and between R and Q is 820 bytes. A TCP segment of size 1400 bytes was transferred from P to Q through R, with IP identification value as 0×1234. Assume that the IP header size is 20 bytes. Further, the packet is allowed to be fragmented, i.e., Don’t Fragment (DF) flag in the IP header is not set by P. Which of the following statements is/are correct?

  • Two fragments are created at R and the IP datagram size carrying the second fragment is 620 bytes.

  • If the second fragment is lost, R will resend the fragment with the IP identification value 0×1234.

  • If the second fragment is lost, P is required to resend the whole TCP segment.

  • TCP destination port can be determined by analysing only the second fragment.

Question 3

Consider an IP packet with a length of 4,500 bytes that includes a 20-byte IPv4 header and 40-byte TCP header. The packet is forwarded to an IPv4 router that supports a Maximum Transmission Unit (MTU) of 600 bytes. Assume that the length of the IP header in all the outgoing fragments of this packet is 20 bytes. Assume that the fragmentation offset value stored in the first fragment is 0.

The fragmentation offset value stored in the third fragment is ______ .

Note -This was Numerical Type question.


  • 0

  • 72

  • 144

  • 216

Question 4

An IP datagram of size 1000 bytes arrives at a router. The router has to forward this packet on a link whose MTU (maximum transmission unit) is 100 bytes. Assume that the size of the IP header is 20 bytes.

The number of fragments that the IP datagram will be divided into for transmission is _________.

  • 10

  • 50

  • 12

  • 13

Question 5

An IP router with a Maximum Transmission Unit (MTU) of 1500 bytes has received an IP packet of size 4404 bytes with an IP header of length 20 bytes. The values of the relevant fields in the header of the third IP fragment generated by the router for this packet are

  • MF bit: 0, Datagram Length: 1444; Offset: 370

  • MF bit: 1, Datagram Length: 1424; Offset: 185

  • MF bit: 1, Datagram Length: 1500; Offset: 37

  • MF bit: 0, Datagram Length: 1424; Offset: 2960

Question 6

Host A sends a UDP datagram containing 8880 bytes of user data to host B over an Ethernet LAN. Ethernet frames may carry data up to 1500 bytes (i.e. MTU = 1500 bytes). Size of UDP header is 8 bytes and size of IP header is 20 bytes. There is no option field in IP header. How may total number of IP fragments will be transmitted and what will be the contents of offset field in the last fragment?

  • 6 and 925

  • 6 and 7400

  • 7 and 1110

  • 7 and 8880

Question 7

Consider sending an IP datagram of size 1420 bytes (including 20 bytes of IP header) from a sender to a receiver over a path of two links with a router between them. The first link (sender to router) has an MTU (Maximum Transmission Unit) size of 542 bytes, while the second link (router to receiver) has an MTU size of 360 bytes. The number of fragments that would be delivered at the receiver is 

  • 4

  • 6

  • 8

  • 10

Question 8

Which of the following statements about IPV4 fragmentation is/are true?

  • The fragmentation of the IP datagram is performed only at the source of the datagram.

  • Fragmentation of IP datagram is performed at only the IP router which finds that the size of the datagram to be transmitted exceeds the MTU.

  • The reassembly of fragments is performed at all intermediate routers along the path from the source to the destination.

  • The reassembly of fragments is performed only at the destination of the datagram.

Question 9

Suppose a message of size 15000 bytes is transmitted from a source to a destination using IPv4 protocol via two routers as shown in the figure. Each router has a defined maximum transmission unit (MTU) as shown in the figure, including IP header.

The number of fragments that will be delivered to the destination is ________ . (Answer in integer)

1


  • 8

Question 10

Consider a network that uses Ethernet and IPv4. Assume that IPv4 headers do not use any options field. Each Ethernet frame can carry a maximum of 1500 bytes in its data field. A UDP segment is transmitted. The payload (data) in the UDP segment is 7488 bytes. Which ONE of the following choices has the CORRECT total number of fragments transmitted and the size of the last fragment including IPv4 header?

  • 5 fragments, 1488 bytes

  • 6 fragments, 88 bytes

  • 6 fragments, 108 bytes

  • 6 fragments, 116 bytes

There are 10 questions to complete.

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