IPv4 (TTL Field)

Question

whenever the packet forwarded by router the TTL value will be decremented by one unit . Is it necessary that TTL value decremented by one unit ??? IT's  values changes by network admin or not

Answer 1

Yes TTL always decrement by 1 unit 

• The purpase of TTL is to identify any loop will exist in packet or not.

• If packet is forwording in wrong direction then then there is a posiblities of forming a loop in packet.

• With in number of hope the packet must be arrive to destination . So TTL field decrement by one in each hope .

• If packet forming a loop TTL value become zero . And router will drop packet.

 

Comments

thank you brother

Answer 2

TTL values decremented by 1 when it passes through network layer device but not decremented in network layer devices or hosts inside a  LAN  because inside LAN packet is forwarded through data link layer .It is not always necessary that TTL value decrements at every network layer device.TTL is also used to identify the infinite loops and number of hops in a network.