[dnsdist] Latency of the DNS resolver

[SAMI RAHAL]

Hello Stephane
Thank you it's very clear



Cordialement,

Sami Rahal
Service Hosting
Direction Technique & SI
Siège Social TOPNET, Centre Urbain Nord
Tél. :71185000
GSM :99 459 812

________________________________________
De : Stephane Bortzmeyer <bortzmeyer at nic.fr>
Envoyé : mardi 2 février 2021 16:07
À : SAMI RAHAL
Cc : dnsdist at mailman.powerdns.com
Objet : Re: Latency of the DNS resolver

On Sat, Jan 30, 2021 at 06:11:01PM +0000,
 SAMI RAHAL via dnsdist <dnsdist at mailman.powerdns.com> wrote
 a message of 228 lines which said:

> I want to know the normal response from a dns resolver server in
> general (the value in ms)

For an authoritative server, it is *sometimes* possible to discuss
"typical" or "expected" response times, but it is impossible for a
resolver.

If the data is in the cache, the resolver replies in one or two
milliseconds or less, if it's "local".

If it is not in the cache, all bets are off since the response time
depends on the authoritative name servers of the queried domain. Huge
latencies are possible if they are far away or slow.

That's why it is very difficult to benchmark resolvers.