? DNS UPDATE ? NSUPDATE ? DYNAMIC DNS ?

[Mike Hunter]

Thanks...I'll give it some thought!

Kevin Darcy wrote:

> You can sorta do this with the rrset-order option available in BIND 8.2 and
> beyond, but, since rrset-order data is not transferred between nameservers,
> you'd need to set this on *every* server which is answering for the name,
> and even then most nameservers answering from cache -- including servers
> you don't control -- will round-robin the answers (you can, of course,
> limit the effects of caching by setting low TTL values for the records, but
> only at the expense of increasing query traffic). So expect some
> "spillover" to your failover servers using this approach.
>
> Note that the caching complication is going to bite you even if you
> implement a homegrown scripted NSUPDATE approach. Any failover approach
> which relies on switching IP addresses around is going to run into the same
> problem.
>
> If you want a "perfect" solution, you'll need to do it at a lower (network)
> level, having a single address which is then somehow magically
> assigned/reassigned behind the scenes in case of a failure, using most
> likely a commercial redundancy/load-balancing product from Cisco, IBM or
> whomever.
>
> - Kevin
>
> Mike Hunter wrote:
>
> > I have a situation where I need a DNS record to point to 3 different
> > servers.  I cannot use round-robin because it needs to resolve in a
> > specific order.  For example:
> >
> > www1    in    a    10.10.10.1
> > www2    in    a    10.10.10.2
> > www3    in    a    10.10.10.3
> > www     in    a    10.10.10.1
> >         in    a    10.10.10.2
> >         in    a    10.10.10.3
> >
> > I need to have DNS to resolve, in order, the first ip address
> > 10.10.10.1, and if it fails, then resolve to 10.10.10.2.  If it fails on
> >
> > the second, then resolve to the third (10.10.10.3).  All automatically.
> > We have looked into possibly using NSUPDATE and writing scripts, but was
> >
> > wondering if there is any way this can be done automatically.
> >
> > Any assistance would be most appreciated.
> >
> > --
> > Mike Hunter                           Schlumberger Omnes
> > UNIX / WAN Element Manager            5599 San Felipe Suite 400
> > Office: 713-513-3233                  Houston TX 77056 USA
> > Fax: 713-513-3150                     Email: mhunter at smc.omnes.slb.com

--
Mike Hunter                           Schlumberger Omnes
UNIX / WAN Element Manager            5599 San Felipe Suite 400
Office: 713-513-3233                  Houston TX 77056 USA
Fax: 713-513-3150                     Email: mhunter at smc.omnes.slb.com