Assumed zone can be wrong

[GeoffreyFrogeye]

Say I want to update foo.dynamic.example.com. It will assume that the zone is dynamic.example.com, however in my case the zone is example.com. The update will fail with this message:

update failed: NOTAUTH
nsupdate command failed.

Two possible solutions:

1. We remove the zone instruction to nsupdate from the template. In my case it works without problem but maybe if this command is here it's for a reason that I don't understand.
2. We need to let the user configure the zones manually.

In both cases the extract_domain_from_hostname function must be removed, because it's wrong.

What do you think?