[34420] in North American Network Operators' Group
Re: How common is lack of DNS server diversity?
daemon@ATHENA.MIT.EDU (Havard Eidnes)
Mon Feb 5 17:33:14 2001
To: trall@almaden.ibm.com
Cc: smcmahon@eiv.com, nanog@merit.edu
From: Havard Eidnes <he@runit.no>
In-Reply-To: Your message of "Sat, 27 Jan 2001 11:13:11 -0800"
<OF015ADF12.B8647026-ON882569E1.0067E9E7@LocalDomain>
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Date: Mon, 05 Feb 2001 23:29:10 +0100
Errors-To: owner-nanog-outgoing@merit.edu
> > Then it probably doesn't matter if you resolve their DNS,
> > because you won't be getting to any of their services anyway.
>
> Several folks have mentioned that they don't see a problem with
> dns failure caused by an inability to reach all of the
> nameservers for a domain - because presumably clients won't be
> able to reach any of the hosts in that domain.
That's a wrong justification, not only due to the reasons you go on
to cite, but because detecting a failure to look up a name takes a
rather long time (your name server or resolver will typically have
to rely on a time-out), while reacting to an ICMP Host Unreachable
as a response to a TCP connection attempt is pretty quick (if your
network is indeed off the net, but your DNS service isn't).
This probably makes for easier debugging / better user reports, less
of a "world wide wait", faster mailing list deliveries and probably
also has other beneficial effects.
Regards,
- H=E5vard
