1,682 views

Checksum field in TCP header is

1. ones complement of sum of header and data in bytes
2. ones complement of sum of header, data and pseudo header in $16$ bit words
3. dropped from $\text{IPv6}$ header format
4. better than $\text{md5}$ or $\text{sh1}$ methods

IPv6 does not have checksum field so c may be answer
Option B and C both are true.

No, IPv6 has dropped it's own checksum (at Network Layer). It can't drop TCP's checksum (at Transport Layer)

### Subscribe to GO Classes for GATE CSE 2022

$\underline{\mathbf{Answer:}\Rightarrow}\;\mathbf{b.}$

All these values are added and stored in one’s complement form.
by
21 48 118

Option B) is correct

Source: Tanenbaum

by
37 89 187

Options B and C both are true.

Explanation:

1. In the TCP header checksum calculation includes the header, data, and pseudo-header. All these values are added and stored in one’s complement form.
2. Higher layer (>=4) protocols like TCP and UDP still have their own checksums. So many lower-layer protocols (<=2) already have their own checksums that having another checksum in IP (layer 3) was seen as unnecessary overhead. Answer is mentioned in stackoverflow .Please refer https://stackoverflow.com/questions/54074898/ipv4-header-included-checksum-but-not-in-ipv6-why
by
1 1 6

For TCP; the sum of header, data and psuedoheader is taken, in 16-bit or 2 Byte words.

Then it's 1's complement is calculated (1's complement $\equiv$ negation) and stored in the checksum field.

Hence, when we add up all the numbers, we'd get $0$

Option B is correct.

Bonus

by
4 8 39

1
1,525 views