Just so I find it again when I run across the same problem in the future:
I wanted to log in to one of my servers and couldn’t access it, because I couldn’t resolve the name from one specific domain. All other domains worked fine.
So let’s head over to the DNS server and check what we can do. I’m running BIND, and it ships with two tools, named-checkconf and named-checkzone. As the name implies named-checkconf checks the overall configuration, named-checkzone single zone. There is also an option -z for named-checkconf that checks all the primary zones found in the configuration.