SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/tech-dns-cache-ttl

What does a DNS record's TTL control?

It controls how long the record may be cached.

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  1. How many labels its name has
  2. Which port the server uses
  3. How long it may stay cached ✔

Why: A DNS resource record includes a time to live measured in seconds. Once that interval expires, a cache should discard the record instead of treating it as current.

Huh, didn't know that: A shorter TTL can make changes appear sooner, but it can also cause more DNS queries.

The dad joke
The DNS record watched the clock because its cache time was limited.
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References

Answer: How long it may stay cached. A DNS resource record includes a time to live measured in seconds. Once that interval expires, a cache should discard the record instead of treating it as current.

  1. RFC 1035: Domain Names, Implementation and Specification www.rfc-editor.org/rfc/rfc1035.html
    interval (in seconds) that the resource record may be cached before it should be discarded.
    Checked 2026-10-10.

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