Multi-master

[Barry Margolin]

In article <9o5bqd$dnl at pub3.rc.vix.com>, Pascal Nobus <pascal at nobus.be> wrote:
>After 10 hours in the dark from our upstream-provider (the first time in 2
>years), we were brainstorming on someting thas is called multi-master I
>guess.
>
>We are working together with another company which has another provider and
>want to do the following.
>
>For all our domains we mention 3 nameservers with the registry:
>ns1.siteA primary on site A,
>ns2.siteA secondary on site A,
>ns3.siteB primary on site B (copy of ns1, done with rsync-over-ssh)
>
>Normally the domains resolve all through CNAME to the name "webserverA".
>
>When site A goes completely in the dark, we change the IP of "webserverA" to
>an IP within the range of siteB.
>If TTL is expired the domains will resolve to the IP of siteB (where there
>is a copy of webserverA).
>
>I don't expect it to work for 100%, but even if 80% is covered after 3
>hours, we're saved.
>And yes, it's better to have two providers with our own routers, but this is
>not reachable for us.
>
>
>But will it work?

I don't see why not.  It's a pretty common disaster recovery mechanism.

>And how low can I set the TTL?

Some nameservers have trouble with TTL=0, but any non-zero TTL should work.

>Which nameservers do I mention in the zone-files?

All 3.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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