Domain Mapping & DNS Best Practices?

We had a situation the other day where the IP Address of our server changed. We had our hosting company install an SSL and another IP. Not sure is that was an error on their part not putting the SSL on the original IP and using the second IP for everything else of if that is standard practice.

The result was we had to repoint all on the mapped domains to the new IP. We have about 20 blogs on our WPMU install now. So while being a hassle not the end of the world just time consuming logging into each domains registrar and updating DNS records.

My question is what is the best way to avoid issues like this in the future? Host the Nameservers on our server? Third party DNS host? Don't mess with the IP in the first place?

I can't imagine trying to fix an issue like this with 100's or 1,000's of blogs.

I'm rather inexperienced with server administration in general. Thanks in advance for the help!!