We host some web sites on servers in our office. We have two internet connections, a primary and a backup connection (with separate IP address ranges.) We need to be able to detect, from outside our LAN, that the primary internet connection has failed.
We use a special DNS service that will switch the DNS records to point at our backup IP addresses if the primary addresses go offline. It detects if our primary addresses have gone offline by pinging a server, or loading a web page on our end, and if that fails, it switches our DNS over to the secondary IP addresses.
We did have it check for the existence of a page on our web server, but the problem is when we reboot that web server for windows updates, it thinks the internet connection has gone down and switches over to the secondary connection, which causes problems. It switches back after a few minutes, once the server reboots.
Up until recently, my procedure was to log into the external DNS and disable the fail-over, then reboot the server, then re-enable it. It's not an optimal solution because the fail-over has to set on on per-domain basis, and there are quite a few.
I would like to have the fail-over check a device which is always on, 100% of the time. Preferably no moving parts on a UPS, so it never goes down. I tried to use a Hawking print server, which has a web-based interface, but it seems unreliable as it has detected the internet connection has failed when it really has not. Worst case, I can build a fan-less PC that boots from USB maybe, and just runs a stripped down unix version with a web host that serves one page.
Are there any simple, 100% reliable devices that could be pressed into service that can be pinged, or serve a web page that could be used?