Priority on A registers

[Kevin Darcy]

delanitaldia at netscape.net wrote:

>Hi,
>
>First of all, I have to say that I am really newby in Bind
>administration, and take my apologies if this question is really
>simple, but I have a problem:
>
>A customer has asked me if it's possible to have a second web server
>that only should respond in case the first web server crashes. I
>thought that it could be resolved with a correctly configuration of
>DNS, but I haven't found anything usefull.
>
>I tried to define two A records for that domain
>
>www   172800  IN      A       1.1.1.1
>www   172800  IN      A       1.1.1.2
>
>But that's the the tipical Round Robin and www.domain.net resolves
>randomly to 1.1.1.1 or 1.1.1.2
>
>But I think I don't need this type of configuration, I need something
>like MX registers that you can configure a priority and in case that
>the most priority server gets a timeout error, it tries to get the
>other priority servers.
>
SRV records provide this functionality (and more), but no web browser 
implementation (that I know of) currently supports their use.

>I am using bind 9.2.2. Do you know how can I solve this problem?
>
Look into load-balancing solutions using separate boxes or devices for 
the purpose.

>I supose that an script asking the web port of the first server and in
>case of no response, automatically changes the zone file of that
>domain to another and making a "rndc reload"  would solve the problem,
>but I don't know if it's the best solution.
>
Yeah, you could cobble together something using a monitoring script and 
(optionally) Dynamic Update, I suppose. You'd have to have set the TTL 
on the A record(s) quite low to defeat caching, however, and that would 
be rather anti-social...

                                                                         
                                          - Kevin