[62580] in North American Network Operators' Group
Re: .ORG problems this evening
daemon@ATHENA.MIT.EDU (Alex Bligh)
Fri Sep 19 11:24:30 2003
Date: Fri, 19 Sep 2003 16:23:27 +0100
From: Alex Bligh <alex@alex.org.uk>
Reply-To: Alex Bligh <alex@alex.org.uk>
To: Todd Vierling <tv@duh.org>, just me <matt@snark.net>
Cc: nanog@merit.edu, Alex Bligh <alex@alex.org.uk>
In-Reply-To: <Pine.NEB.4.58.0309181000260.8936@server.duh.org>
Errors-To: owner-nanog-outgoing@merit.edu
--On 18 September 2003 10:05 -0400 Todd Vierling <tv@duh.org> wrote:
> DNS site A goes down, but its BGP advertisements are still in effect.
> (Their firewall still appears to be up, but DNS requests fail.) Host
> site C cannot resolve ANYTHING from DNS site A, even though DNS site B is
> still up and running. But host site C cannot see DNS site B!
What you seem to be missing is that the BGP advert goes away when the DNS
requests stop working.
I have written DNS/BGP code (nothing to do with UltraDNS) and I can tell
you it works very well. Even if you unplug the machine from the net you can
get rapid failover by tweaking a BGP timer here or there. If you are going
to say "yes but that means I don't have one of the servers up whilst
routing reconverges" this is true, but (a) it happens ANYWAY, (b) as the
prefered route is in general more local, the "rainshadow" from routing
reconvergence in the event of disruption is smaller.
Alex
