Time to live

Question

When is TTL decreased?

1- only at routers?

2- any device having network layer (including hosts in between the path) :

example: source subnet has ethernet and destination subnet has token ring : all hosts and routers that come in packets.s path will decrease TTL or only router will decrease TTL?

Comments

hosts in the path have network layer too, like in token ring , so ttl is decreased there too?

 

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follow this: https://gateoverflow.in/1983/gate2014-2-25

Answer 1

TTL not only decrease on routers but it can decrease at any at any device having network layer .TTL also decreases at the destination.

TTL stands for time to live .It is a field of 8 bits in the IPV4 header and is used to detect the infinite loops.Basically TTL decreases at every Hop .Hop may be from source to router or router to router of router to destination.

Comments

hosts in the path have network layer too, like in token ring , so ttl is decreased there too?

 

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TTL value decreases at every network layer but never decrease inside the LAN because inside LAN it never goes through network layer ,it is forwarded through the data link layer

for example if source assign TTL value as 10 in that case it will be decremented by 5 routers and 1 destination means total 6 so finally 10-6=4

Answer 2

TTL decreases at all the networking devices untill it reaches the destination..even it also decreased at destination.