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Glossary Web & HTTP

TTL

TTL (time to live) is how long, in seconds, a DNS record or cached item may be reused before it must be fetched again.

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In more detail

A DNS TTL of 300 lets resolvers cache an answer for five minutes. Short TTLs make changes take effect quickly but increase lookups; long TTLs are efficient but slow to change. In IP packets the TTL field means something different: a hop counter that drops by one at every router and discards the packet at zero, preventing endless loops.

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See also

  • Glossary DNS
    DNS (Domain Name System) is the internet's directory that translates domain names like example.com into IP addresses and holds other.
  • Guide How DNS Works
    How a name becomes an IP address through resolvers, root, TLD and authoritative servers, the record types, TTL and caching.
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