Numbering nameservers and resolvers

Wed Aug 18 13:37:09 UTC 2010

Mikael Abrahamsson <swmike at 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