Re: DNS anycasting - multiple DNS servers on same subnet Vs registrar/registry policies

["Patrick W. Gilmore" <patrick () ianai net>]

On May 28, 2012, at 15:24 , Anurag Bhatia wrote:
> On Tue, May 29, 2012 at 12:50 AM, Tony Finch <dot () dotat at> wrote:
> > Anurag Bhatia <me () anuragbhatia com> wrote:
> > > One small concern I wanted to discuss here. I know few
> > > registry/registrars which do not accept both (or all) name servers of
> > > domain name on same subnet. They demand at least 1 DNS server should be
> > > on different subnet for failover reasons (old thoughts).
> > >
> > > How one can deal with such case in case of anycasting setup which using
> > > one single subnet everywhere?
> >
> > You still want name servers on more than one subnet in case the anycast
> > setup breaks.
> I am building redundancy within that setup. I mean it will be software
> based BGP so if hardware if fried up, it will break BGP session and pull
> off routes anyway and for cases like DNS server (software) failure, I will
> monitor it via simple bash script which can turn bgp daemon down. So once
> it is off, routing tables should take it to different node.

Famous last words: "I am building redundancy...."  As if "redundancy" stops someone else announcing your prefix and 
sucking in half the packets on the 'Net meant for you.  (Just one of many failure modes against which you cannot 
possibly defend.)

That said, IMHO, if you want to shoot yourself in the foot, you should be allowed to do so.  Your foot, your decision.  
I'm sure there are registrars out there that do not babysit you.  Find one that doesn't tell you how to run your own 
infrastructure.

And enjoy the extra spice that gives your life. :)

-- 
TTFN,
patrick