What is ttl in ping

This thread is locked. You can follow the question or vote as helpful, but you cannot reply to this thread. I have the same question Report abuse. Details required :. Cancel Submit. TTL means "time to live". It is a value on an ICMP packet that prevents that packet from propagating back and forth between hosts ad infinitum. Each router that touches the packet decrements the TTL. Every bit of data on IP networks is sent using packets, and there are almost always one or more routers in between two computers speaking to each other on the internet.

However, sometimes things can go wrong, and routers can end up forwarding packets back and forth to one another forever. This is called a routing loop, and, there need to be protections in place to prevent these packets from being forever passed back and forth in the network.

TTL is a bit of data kept with every packet, indicating how many more routers, or hops, it is allowed to pass between before expiring. For every router a packet passes through, this TTL value will be decreased by 1. When the value reaches zero, the router handling that packet will drop the packet and will send a warning message back to the sender, letting them know the TTL expired. Because the TTL to reach specific destinations can be useful for diagnosing problems, and because ping is a diagnostic tool, this is why ping provides the TTL alongside the better known data of ping times.

Learn more. Asked 1 year, 2 months ago. Active 1 year, 2 months ago. Viewed 2k times. TTL value of a packet is supposed to decrease 1 at each router from down to zero as follows: But when I ping to 8. Improve this question. Please, never use an image for text. Add a comment. Active Oldest Votes. Improve this answer.

Jeff Wheeler Jeff Wheeler 4, 7 7 silver badges 17 17 bronze badges. Linux kernel 2. The TTL represents the number of hops, or servers in different locations, the request can travel to before returning a failed attempt message.

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