IPV4 header

Question 1

What is in the IPv4 Header?

Answer 1

1. Version
2. IHL (Internet Header Length)
3. DSCP (differentiated services code point)
4. ECN (Explicit Congestion Notification)
5. Total Length Field
6. Identification field
7. Flags
8. Fragment offset
9. TTL
10. Protocol
11. Header checksum
12. Source IP address
13. Destination IP address
14. Options

Question 2

Version (IPV4 Header)

Answer 2

Denotes whether Packet is IPV4 or IPV6

Question 3

IHL

Answer 3

(Internet Header Length - Indicates the total length of the header (only ipv4 header) in increments of 5

Question 4

DSCP

Answer 4

differentiated services code point - used to identify if data should be prioritized

Question 5

ECN

Answer 5

Explicit Congestion Notification - end to end notification of congestion without dropping

Question 6

Total Length field

Answer 6

Length of the packet (l3 + l4 header)

Question 7

Identification field

Answer 7

If fragmented due to exceeding MTU, this will keep track (fragments will have diff headers but same identification).

Question 8

MTU

Answer 8

Maximum size of the packet that can be sent at a time (fragments if too big)

Question 9

Flags

Answer 9

control and identify fragments

Question 10

Fragment offset

Answer 10

indicate position of fragment within original packet

Question 11

TTL

Answer 11

counts down everytime it reaches a router, will be dropped at 0

Question 12

Protocol

Answer 12

indicates protocol of encapsulated l4 PDU (ie TCP)

Question 13

Header Checksum

Answer 13

Checks for errors in the header by having router calculate checksum and dropping if it doesn’t match