[dns-operations] Quick anycast primer

[Jim Reid]

On Jul 14, 2006, at 08:41, Steve Gibbard wrote:

> In a typical anycast cloud, there are several servers in several  
> locations
> sharing a service address.  When all servers in the cloud are up, and
> routing to all of them is working properly, queries sent to that  
> service
> address are responded to by the topologically closest server.

....modulo peering agreements/policies.

Once upon a time Steve, some of my zones were served on Nominum's  
anycast service, GNS. [You might have had a hand in setting that up  
with Bill Woodcock.] When I queried the anycast address from home,  
the packets went to LINX where they waved at the Nominum servers on  
their way to the anycast instance in Palo Alto. And back again. This  
was because the ISP I used in those days didn't peer with Nominum in  
LINX. Their upstream provider did that at PAIX.

I suppose it all depends on what's meant by "topologically closest".