A recurring theme here is one of user expectation. Or I should say, the expectation I have as an old school Unix administrator (that doesn't really care for Unix administration but can do it) and the current state of the art in Unix—or rather, Linux—administration.
Today's project was a consolidation of DNS (Domain Name Service)—moving all the zone files to a central server and have that one serve the zones to the actual register name servers. That way, we have one location to make changes and from there they are propagaged out. Nothing too wild.
But it's not working. The zone transfers are failing. Big time. I'm reading the Cricket Book (DNS and Bind, Fourth Edition) [1] and I'm close to really mucking with the configuration files when this little voice in the back of my head goes Hey, check to see if there's a firewall running on the server. See, user expectation—I'm not used to Unix servers running firewall software as a default. I'm not running Windows [2] for crying out loud.
And thankfully, it turns out to be a firewall issue. Otherwise I thought I was going crazy.
[1] http://www.amazon.com/exec/obidos/ASIN/0596001584/conmanlaborat-20