Knot DNS Server
Given it support adding and removing of zones on the fly, it could be preferable to NSD for something that I’ve currently got in production.
Update: Turns out NSD4 solves all the issues I had with NSD3, which is nice. I gave up on Knot DNS as it kept failing to stop, and wouldn’t give me a hint of why. Checked the zonefiles and the config, and they all were fine. Oh, well…
I just wish I could use NSD4 in that production system, but it’s not available for Debian 7.3 (wheezy).