Probe dns service - anycast network

Thu Nov 11 23:13:52 UTC 2004

On 11 Nov 2004, at 18:02, Gere geomag wrote:

> We are thinking of deploying anycast in our network for dns servers.
> I have the following scenario:
>  - 10 server DNS (isc-bind) , linux and zebra for propagating ospf ip 
> anycast.
>
> Are there someone who has developed a "solid scripts (perl/c/ecc..)"
> that is used to probe a dns service (udp/tcp port 53) and in case of
> failure (or max lookup query time problem) automatic shutdown ospf
> annunce or remove a server from a anycast network?

This doesn't quite answer your question, but there's a wrapper script 
here:

   http://www.isc.org/pubs/tn/isc-tn-2004-1.html#appx.WrapperScript

which kind of does what you're asking. It relies on BIND 9 dumping core 
upon experiencing an assertion failure (or any kind of failure which is 
likely to cause it to fail). BIND 9 is quite good at dumping core when 
it gets confused (by design, in case anybody thinks I'm being 
sarcastic).

You could always augment that with a crob job which does some digs, and 
creates ${stop_file} and kills  named in the event that the digs fail. 
Testing remotely may also be a good idea. There are allusions made in:

   http://www.ietf.org/internet-drafts/draft-kurtis-anycast-bcp-00.txt

to some of the monitoring and measurement issues surrounding anycast 
service deployments. In any case, there are many ways to skin this cat.

Joe