building a DNS system

[Kevin Darcy]

vincentbruno at free.fr wrote:
> Hi,
>
> Actually I am using a DNS server which activities are:
> - handling about 3000 domains as master nameserver
> - processing mail forwarding
> - performing some HTTP queries (like web forwarding)
>
> I want building a dedicated secondary server with the same
> functionality if the first one is down.
>
> Primary server: Fedora FC3, Bind 9.5.2
> Secondary serveur: Fedora FC3, Bind 9.5.2
> A domain name: mydomain.com with the two nameservers above.
>
> Processing mail forwarding is easy, the domain name is defined with two
> MX records (the first nameserver and the secondary nameserver) but
> about web forwarding...
>
> I define my zonefile on both nameservers :
>
> $TTL    3H
> @               IN              SOA     PRIMARY_SERVEUR. MAIL. (
>                         2006071416; Serial
>                         3H          ; Refresh
>                         2H          ; Retry
>                         1W          ; Expire
>                         1D )      ; Minimum
>         IN NS       PRIMARY_SERVEUR.
>         IN NS       SECONDARY_SERVEUR.
>         IN MX 0    PRIMARY_SERVEUR.
>         IN MX 10  SECONDARY_SERVEUR.
>         IN A         IP_OF_PRIMARY_SERVEUR
> www IN A         IP_OF_PRIMARY_SERVEUR
>
> If the primary server is totally down:
> DNS will be handled by the secondary NS -> OK
> Mail will be handled by the secondary MX = secondary NS -> OK
> http will be handled by IP_OF_PRIMARY_SERVEUR which is down -> no web
> forwarding available.
>
> What is the solution ?
> Do I need a third server which will process http queries and each A
> record points to its IP, but if this server is down ?
> Can I use only two servers ? if yes, how ?
>
> Thanks for your replies !!! :)
>   
Have the www name resolve to the addresses of both web servers. If the 
failover delay is not acceptable to you or your users, then look into 
some dedicated load-balancing solution or service.

In the long term, web browsers should have the capability to use SRV 
records to access web sites, which are "preferenced" like MX records. 
But browsers don't support SRV yet. So in the meantime, we're stuck with 
either the "cheap" round-robin solution, or relatively-expensive 
solutions involving proprietary hardware or software.

                                                                         
                              - Kevin