Time to Live

From SuperbHosting.net Support Wiki

Time to live (TTL) is the limit on either the period of time or the number of iterations/transmissions in computer and computer network technology that a unit of data can experience before it should be removed or thrown out.

TTLs can also be found in the Domain Name System (DNS), where they are implemented by an authoritative nameserver for a particular resource record. When a caching nameserver queries the authoritative nameserver for a resource record, it will cache that record for the time (usually in seconds) specified by the TTL. If a stub resolver queries the caching nameserver for the same record before the TTL has expired, the caching server will simply reply with the already cached resource record rather than get it from the authoritative nameserver again.