The primary server had DNS accidentally removed. Now the secondary server can not load the zone. Can I switch the secondary server from a secondary zone to a primary zone?
Secondary is NT3 and primary is Windows 2003. This is not AD integrated.
It's been awhile since I've seen the Windows NT DNS screens as well, but if memory serves me correctly, some things haven't changed much since those days in regards to non-AD DNS zones, to whit:
Check on the W2K3 server in the system32\DNS folder for the DNS zone file. If it still exists you can simply reinstall the DNS role and create a new zone, selecting the option to use an existing file, and make sure the file name matches the name of the actual file (domain.tld.dns).
If the zone file doesn't exist you can copy it from the Windows NT server (which will have a copy of it in the system32\dns directory) to the W2K3 server, reinstall the DNS role on the W2K3 server and perform the same steps as above.
If you look at the zone file on the W2K3 or NT server you'll see that the W2K3 server is listed as the SOA for the zone and that both servers are listed as NS'es for the zone. You can manually edit the file to your hearts content to make any changes needed.
The following are for Windows NT 4 but I believe they hold true for Windows NT 3.x as well:
It has been a long, long, long time since I saw the NT DNS screens, but I'm pretty sure it is possible to promote a secondary to primary. There may be issues, but it can be done. So long as none of the records have TTLed out, it should still have a complete copy of the zone file.
And if all else fails, I think you can just copy the 2003 zone file (it may still be there!) over to the NT3 server. Way back in my NT classes they were saying it was just a BIND-compatible file, though I won't vouch for the version of bind. You may need to do some syntax cleanup.