[dns-operations] Load balancing DNS queries across many machines

Michael Sinatra michael at rancid.berkeley.edu
Fri Jul 17 12:44:51 UTC 2009

On 07/16/09 22:11, Michael C. Toren wrote:
> On Thu, Jul 16, 2009 at 05:48:19PM -0700, Michael Sinatra wrote:
>>> Do they anycast individual machines and
>>> just rely on multipath routing to load balance, or put all of the
>>> machines on the same network and use VRRP or CARP, or do any sites use
>>> higher level protocols for load balancing?
>> anycast + equal-cost multipath routing via an IGP such as OSPF or IS-IS. 
>> UC Berkeley has been doing this since 1999.  I am sure there are others 
>> who have been doing it longer.
> When using equal-host routing, presumably you're also using per-path
> load-balancing, rather than per-packet load-balancing, in order to
> support TCP queries?


> Can you tell us how many hosts you're using equal-host routing to?

There are two anycast clouds with four hosts each, so there's a total of 
four potential equal-cost routes.


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