I'm working with a church that has a website hosted by an outside company that handles all of the DNS for them (we just point our NS records to their servers). The platform (FaithConnector) includes email hosting that is currently used only for distribution lists. The church is wanting to use Google Apps for individual staff emails, but unfortunately we don't have access to the nameservers at FaithConnector to add the necessary MX records. My question is, if we add our own nameserver with the appropriate records for GApps, is there some way to configure it so that we can continue to use the current platform for the distribution lists and avoid breaking anything?
As far as systems wanting to do a lookup are concerned all your nameservers are equal. It follows therefore that if you have different records on different servers you can, at the very least, expect some pretty unpredictable results.
When done correctly you will have one master server with one or more slaves which sync to the master. But, to repeat what I said previously, to the clients they are all equal. If you cannot set it up this way because one server isn't providing the needed flexibility or functionality then you need to look at eliminating that server from the equation.