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Re: DNS Anycast as traffic optimizer?

  • From: Steve Francis
  • Date: Wed Sep 01 14:25:35 2004

Bill Woodcock wrote:

     On Wed, 1 Sep 2004, Steve Francis wrote:
   > I'm sure there is research out there...

Why? :-)


Usual - if I build it myself, will it work well enough, or should I pony up for a CDN?

> ...how good/bad using DNS anycast is as a kludgey traffic optimiser?

I'd hardly call it a kludge. It's been standard best-practice for over a
decade.


I thought it was standard best practice for availability, like for root name servers. I thought it was not a good "closest server" selection mechanism, as you'll be going to the closest server as determined by BGP - which may have little relationship to the server with lowest RTT.
It'd be nice to see some metrics wither way....

   > THe question is, what is that "some" relationship?  80% as good as
   > Akamai?  Terrible?

Should be much higher than Akamai, since that's not what they're
optimizing for.  If you want nearest server, anycast will give you that
essentially 100% of the time.  Akamai tries to get queries to servers that
have enough available capacity to handle the load.  Since they're handling
bursty, high-bandwidth applications, rather than DNS.

-Bill