time to live
A counter in every IP packet that each router lowers by one, so a packet caught in a loop is eventually discarded.
In more detail
When it reaches zero the router returns an ICMP time exceeded message, which traceroute uses to list the hops. DNS records also carry a TTL, saying how long they may be cached.
Related terms
- Internet Control Message Protocol — The network protocol that carries control and error messages, such as the echo requests and replies that ping sends.
- mtr — A tool that combines ping and traceroute, showing loss and latency at every router on the path to a host.
Taught in
- The Tracker Is Down, For Some People: Link, Address, Route, Name And Port — CompTIA Linux+ (XK0-006) Exam Prep