>Hello All,
>
>We have a backup adsl connection for if our SDSL goes down. When our primary ISP goes down the router automicly switches to our back up ISP allowing our uses to still use the internet.
>
>We are also hosting our email and webserver in the office and we would like it so when our primary ISP goes offline clients can still access our website and mail server.
>
>How I imagine we would do this is have two IP addresses registered for each service (example):
>
>Website: 212.212.212.212
> 64.64.64.64
>
>mail: 212.212.212.213
> 64.64.64.65
>
>At the domain registrar level have DNS1 pointing to dns server at primary ISP and have DNS2 pointing to backup ISP dns.
>
>Is this correct? If not am I close? Does any one know of any good materials on doing something like this?

I think what you actually need is a so-called "dynamic" DNS service, such as http://www.no-ip.com/

In your proposal, it is likely that your primary ISP's DNS server will still be up, even if your connection is down. In that case, visitors will still be directed to your primary site address, even though it's inaccessible. The secondary/backup DNS server would only ever be accessed if DNS1 was actually down, which has no relation to whether your connection is down.