Depends what you mean by "defining DNS query/response latency". If you are meaning "The latency from a stub to a recursive MUST be less than 100ms. The latency from a recursive to an auth MUST be less then 123.4ms", then no, I don't think that there is anything like that (modulo timeouts and similar).
There are, however, many RFCs about the desire to minimize latency, including things like: RFC9824 - "Compact Denial of Existence in DNSSEC" <https://datatracker.ietf.org/doc/rfc9824/> - saves small bits of time by not having to fetch from a DB style setup. RFC9715 - "IP Fragmentation Avoidance in DNS over UDP" <https://datatracker.ietf.org/doc/rfc9715/> - by not failing over to TCP, you can save quite a few RTT. RFC9520 - "Negative Caching of DNS Resolution Failures" <https://datatracker.ietf.org/doc/rfc9520/> - if you cache non-response answers you can immediately return these to clients. RFC9276 - "Guidance for NSEC3 Parameter Settings" <https://datatracker.ietf.org/doc/rfc9276/> - a bit of a stretch, but not doing iterations saves, um, many microseconds. RFC9210 - "DNS Transport over TCP - Operational Requirements" <https://datatracker.ietf.org/doc/rfc9210/> - if you *do* have to fail over to TCP, making sure it actually works means clients get an answer, and don't just hang. RFC9156 - "DNS Query Name Minimisation to Improve Privacy" <https://datatracker.ietf.org/doc/rfc9156/> - trades some latency to improve privacy RFC8906 - "A Common Operational Problem in DNS Servers: Failure to Communicate" <https://datatracker.ietf.org/doc/rfc8906/> - if you don't answer, or answer incorrectly, some queries take much longer. RFC8806 - "Running a Root Server Local to a Resolver" <https://datatracker.ietf.org/doc/rfc8806/> - by having zones locally you don't need to do a lookup. RFC8198 - "Aggressive Use of DNSSEC-Validated Cache" <https://datatracker.ietf.org/doc/rfc8198/> - if you know (through e.g NSEC) that a name doesn't exist, you can immediately send back a negative answer. RFC8020 - "NXDOMAIN: There Really Is Nothing Underneath" <https://datatracker.ietf.org/doc/rfc8020/> - same. If you get an NXD for foo.example, you know that bar.foo.example doesn't exist RFC7706 - "Decreasing Access Time to Root Servers by Running One on Loopback" <https://datatracker.ietf.org/doc/rfc7706/> - same as RFC8806. RFC4472 - "Operational Considerations and Issues with IPv6 DNS" <https://datatracker.ietf.org/doc/rfc4472/>, RFC3901 - "DNS IPv6 Transport Operational Guidelines" <https://datatracker.ietf.org/doc/rfc3901/> - Make DNS fast by making sure IPv6 works too…. RFC3258 - "Distributing Authoritative Name Servers via Shared Unicast Addresses" <https://datatracker.ietf.org/doc/rfc3258/> - A big one. Any cast FTW! W On Mon, Jan 26, 2026 at 11:19 PM, Cathy Zhang <[email protected]> wrote: > Hello everyone, > > Are there any RFCs or drafts defining DNS query/response latency? > > Regards, > Cathy > > _______________________________________________ > DNSOP mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
_______________________________________________ DNSOP mailing list -- [email protected] To unsubscribe send an email to [email protected]
