I have an old domain that was first set up in NT4 days. It has been through several admins, some better than others. The last upgrade done was from 2003 to 2008 R2 via a migration to new DCs. I'm now receiving several strange NTP errors.
I tracked this down to DNS resolution problems for my internal domain.
There are about half a dozen entries for mydomain.org:
- 100.100.100.6 (legacy DC, demoted)
- 192.168.100.80 (new NC)
- 18.104.22.168 (web server)
- 100.100.100.0 (?)
- 172.16.1.0 (?)
- 192.168.100.81 (2nd new DC)
- 100.100.100.15 (legacy DC, demoted).
All that I should need here for proper AD function is the two new DCs correct?