Failover using DNS

[Kevin Darcy]

You can't do this reliably using only DNS, unless you happen to control
the configurations of *every* DNS server that could possibly be
answering this query, including all servers which cache the name and
answer it to their local clients (in which case you could configure them
all with a "fixed" rrset-order for the name).

The long-term solution to this problem is to get SRV record support in
all browsers. Until then, the only other (expensive) alternative is L4
load-balancing and/or failover.

Perhaps you should consider mirroring the website on both servers. Then
regular DNS round-robin would probably do the job (and you could remove
an address from the list if one of the webservers goes down).


- Kevin

Fabio wrote:

> I have two similar web server with two different IP addresses:
> 10.0.0.1 and 10.0.0.2
> I want that www A record pointing to 10.0.0.1 but when this host is
> down, and only in this case, I also want to redirect all traffic to
> 10.0.0.2
> This configuration doesn't work, because Round Robin isn't indicated
> for my job (only when 10.0.0.1 is down the traffic must be passed to
> 10.0.0.2!!!)
>
> www                     IN      A       10.0.0.1
> www                     IN      A       10.0.0.2
>
> Please help me.
>
> Fabio Erri.