[dns-operations] Anycast vs. unicast NS

Edward Lewis Ed.Lewis at neustar.biz
Thu Mar 17 18:06:58 UTC 2011

I'm pretty sure we have some unicast-free TLDs. 
(E.g., dotUS.)  We haven't seen any problems 
particular to the anycast v. unicast approach.

Observing a low query count at a server, 
regardless of any/unicasting can be the result of 
two things.  One is the DNS-layer issue of just 
being slow and thus not preferred.  Two is the 
network-layer artifact of who sees the route.

With anycast, a server that is advertised to just 
a few hosts will see less traffic than a server 
(at the same IP address) whose path is advertised 
globally.  As far as unicast, it might be that 
the servers route is just lost in the clutter. 
(I'n not so much a routing person.)

At 17:47 +0100 3/17/11, Jaroslav Benkovský wrote:
>Hi all,
>Speaking of anycast deployment, has anybody observed problems with
>having *all* authoritative servers in anycast cloud(s)?
>We are considering switching off the last non-anycasted servers for the
>.CZ zone, and actual experience of other TLDs would be welcome.
>We do not see significant amount of queries to the unicast servers, on
>the other hand our experiments suggest that unicast servers have better
>chance to be reachable from networks with problematic routing.
>Jaroslav Benkovsky
>dns-operations mailing list
>dns-operations at lists.dns-oarc.net

Edward Lewis
NeuStar                    You can leave a voice message at +1-571-434-5468

Me to infant son: "Waah! Waah! Is that all you can say?  Waah?"
Son: "Waah!"

More information about the dns-operations mailing list