1. Set up a server using "dns forwarder" to forward unknown requests.
2. Preform a lookup on a domain that requires Samba to forward the request (test.domain.com).
3. Create a DNS zone in Samba called domain.com, with new records.
4. Samba still forwards the request to the forwarder - it doesn't look at the new zone in Active Directory.
5. Restarting Samba will clear and resolve the issue.

The same result when removing a zone:

1. Set up a server using "dns forwarder" to forward unknown requests.
5. Ensure the domain will be resolvable by the forwarder.
2. Create a DNS zone in Samba called domain.com, with new records.
3. Preform a lookup on a record in the zone (test.domain.com).
4. Delete the zone from Active Directory.
5. Even though the zone is available at the forwarder, Samba will return no records.
6. Restarting Samba will clear and resolve the issue.

Most recently tested on Samba 4.0.7 and 4.0.7-SerNet-RedHat-4.el6