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

[Mark Andrews <marka () isc org>]

In message <5EBC0868-05D2-435E-A671-E957AF72F506 () one com>, Mikkel Mondrup Krist
ensen writes:
> On May 29, 2012, at 01:56 , Brett Frankenberger wrote:
>
> > On Mon, May 28, 2012 at 09:32:29PM +0200, Stephane Bortzmeyer wrote:
> > > On Tue, May 29, 2012 at 12:21:10AM +0530,
> > > Anurag Bhatia <me () anuragbhatia com> wrote 
> > > a message of 28 lines which said:
> > >
> > > > I know few registry/registrars which do not accept both (or all)
> > > > name servers of domain name on same subnet.
> > >
> > > Since my employer is one of these registries, let me mention that I
> > > fully agree with David Conrad here.
> >
> > How does your employer know if two nameservers (two IP addresses) are
> > on the same subnet?
> Registrars are still rocking classful routing like its 1993.

As long as they are covered by the same BGP anouncement they are
NOT redundant.  It shouldn't be that hard for registrars to take a
full bgp feed and use it to validate.  If it's in the same /24 for
IPv4 it may as well be in the same subnet even if you have smaller
subnets internally.  The world only listens to the one announcement.

For those of you who thing that if your net is down you don't need
to be able to respond to DNS requests, the DNS is not designed to
handle non reachable zones.  It's designed to handle some of the
nameservers for a zone being unreachable.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka () isc org