resolv.conf question

[Ralf Hildebrandt]

>     Ralf> My question: Is there any way to automatically reorder the
>     Ralf> server in such a way, that query time is optimal?
> 
> No. And even if there were, few applications would be able to exploit
> it. Most applications make 1 DNS request - maybe repeated to 2 or 3
> name servers - and then don't do another DNS lookup after they've got
> the answer.

? 
I thought the programs would use resolver routines, and the resolver would
take care of the resolution itself.

So the resolver would have to keep track of the reachability (like xntpd)

> So keeping track of the round trip times would be
> pointless for most things that use the DNS. The rotate option in the
> BIND8 resolver might help a little, but only for the handful of
> applications which make lots of DNS lookups. And even then this only
> round-robins queries between the three nameserver directives, so the
> bad name server(s) still get queried.

What exactly is the name of that option (so I can look it up in the docs)?

>     Ralf> Reason: We had several customers complaining about bad
>     Ralf> performance, and one of the main resons was that the
>     Ralf> nameservers in their /etc/resolv.conf's were not answering
>     Ralf> their machine's queries.
> 
> Why not get those customers to set up their resolvers to point at
> reliable name servers? That would be the simplest and most obvious
> solution. It seems a bit silly to fire DNS lookups at name servers
> that don't respond.

Well, they USED to respond...