nanog mailing list archives

Re: Numbering nameservers and resolvers


From: "Robert E. Seastrom" <rs () seastrom com>
Date: Wed, 18 Aug 2010 09:37:09 -0400


Mikael Abrahamsson <swmike () swm pp se> writes:

On Tue, 17 Aug 2010, Nick Olsen wrote:

So lets say that you have multiple DNS resolvers in the same ip space that
you advertise from multiple locations. All would be fine for the most part.
But if you had a location equidistant network wise from two POP's wouldn't
it load balance and possibly break some TCP sessions? How would someone get
around this? This is also what OpenDNS does from what I understand.

Usually network do not loadshare per-packet on BGP, so a TCP session
will "always" go to the same dns server, at least for the short
duration this TCP session lives.

Occasionally I have seen networks (usually small dual-homed ones) that
attempt to equally utilize their network pipes by doing per-packet bgp
load balancing to both upstreams.  Then they wonder why their
performance is so irregular.  :-)

-r




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