Resolvers

2 articles

Tech 16 Sep 2026 5 min read

DNS Negative Caching Temporarily Stores Name Errors

A DNS cache does not store only successful answers. Recursive resolvers can also retain authoritative responses that say a requested name or record does not exist. This behavior is called negative caching. Negative caching reduces repeated work. If many clients ask for the same absent name, a resolver can answer from its cache instead of sending the same query through the DNS hierarchy each time. The trade-off is temporal. If an administrator adds the missing record while a negative answer is still cached, some clients can continue receiving the cached error until its negative cache lifetime expires.

DNS Networking

Tech 15 Sep 2026 7 min read

DNS Negative Caching Keeps Failed Lookups Temporary

A DNS lookup does not always return an address or another requested record. An authoritative server can report that a domain name does not exist, or it can report that the name exists but has no record of the requested type. Recursive resolvers can keep these negative answers in cache for a limited period. That behavior reduces repeated traffic for the same failed lookup and prevents authoritative servers from receiving identical questions on every client attempt.

Networking DNS