National/International link

[Mark_Andrews at isc.org]

> In article <9vda4r$iv1 at pub3.rc.vix.com>,
> Cecilia Cabrera  <ccabrera at ccc.uba.ar> wrote:
> >Hi, i've got a situation here that's been driving me nuts, hope you can
> >give me some ideas.
> >
> >It goes like this: our LAN has an international link plus a national link.
> >Whenever the international link goes down the DNS servers can't acces to
> >the root servers and don't resolve the names out of his SOA
> >(mydomain.ar and others.mydomain.ar). Figures.
> >YET, since i do have a national link up i would like them to resolve the
> >.ar domains. Specially since the load of so many "unresolvable" requests
> >end up killing my servers until they can't even answer for mydomain.ar
> >(quite a nuisance). 
> >
> >So, my root.zone has some entries for ar. but from what i've read i
> >believe the named doesn't notice them, right? How can i teach him the
> >ar. NSes regardless of the root nameservers? 
> 
> If any of the authoritative servers for .ar allows you to pull zone
> transfers, you could configure your server as a slave.
> 
> Other than that, I don't see a good solution. 

	Stub zones will allow you to prime the server with the ar
	nameservers.

	e.g.
		zone "ar" {
			type stub;
			file "ar.stub";
			masters { 200.10.202.3; 200.16.98.2; 200.16.97.17; };
		};

	However the real problem is that the routing in not failing over to
	use the second link when the first is down.

	Mark

> The problem is that the TTL
> of the .ar NS records are only 1 hour.  Most TLDs have TTLs set to several
> days, and if .fr were like this you would usually be able to use the cached
> NS records while your international link is down.  Maybe you should contact
> the Argentina NIC and find out why they've set the TTL so low.  It seems
> unlikely that the NS records change very often, so there should be little
> reason to reduce caching like this.
> 
> -- 
> Barry Margolin, barmar at genuity.net
> Genuity, Woburn, MA
> *** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
> Please DON'T copy followups to me -- I'll assume it wasn't posted to the grou
> p.
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org