I assume you’re running a dedicated server, since you say you have 2 static IP addresses. Have you considering just running your own authoritative DNS server for your domains on the same server? If your own server is down, the fact that your DNS is down won’t matter.
On Linux, I recommend djbdns. http://cr.yp.to/djbdns.html
For a more friendly guide to getting it running, try
http://www.djbdnsrocks.org/