With reference to http://bugs.debian.org/826214, please be aware
that /lib/init/init-d-script is broken and this results in
a situation wherein the nsd init.d script does not properly
integrate with systemd. This is manifested by the init.d script
ending up using the nsd-control tool to start the process, without
putting it under control of systemd. Subsequently, trying to
control the process with systemd will fail.

An easy way to check is whether nsd has been invoked with the -d
argument. If yes, it's run by systemd. If not, then it was started
by the init.d script.

It would be best AFAICT to rewrite the init script to not use
init-d-script, but to do the integration manually.

Thanks for your attention,
martin