bind named records not updating properly

If DNS records are not updating properly, appear inconsistent or random but zone file looks fine...

This usually means that somewhere you forgot to update a serial for the domain and new zone info is not propagating to slave servers. The best long-term solution is to (at least) use a script to 'wrap' edits to your zone files. The script runs sed at the end to update the serial. Other solutions involve putting all your zone info in a database and then building zone files from the db "automatically". This means you can't create a corrupt zone file by accident (nasty), and you can run as many nameservers off the db as you like, making multiple nameserver maintenance a breeze.