Lately i had problems logging in to some computers in my Windows domain. Error messages about computer not having account in the domain. When clicking on some computer in Explorer that path is not available. I noticed that one domain controller had failed to sync for a month. When i turned off that domain controller it got better. I decided to reinstall that DC. I could make it into domain controller. Server manager hanged on configuring AD DS service. In DCPROMO.LOG i saw
11/13/2022 02:04:27 [INFO] EVENTLOG (Error): NTDS Replication / Setup : 1125
The Active Directory Domain Services Installation Wizard (Dcpromo) was unable to establish connection with the following domain controller.
Domain controller:
N2820.myaddomain.org
Additional Data
Error value:
1722 The RPC server is unavailable.
I did a search with Google. The reasons i found for that error Message is that some services are not running or DNS error. All services were running. After looking at DNS records for a long time i saw that they were there. 🤔I tried using dcdiag. It complained about DNS records missing. I tested with nslookup and dig. All records from netlogon.dns were available. That should be enough for promoting a computer to domain controller. I could not get the DNS server on my DC to listen to its IPv6 address. I gave up on that. I looked at the event logs on the DC to see if i could find some error message telling me why i could not promo another computer to a DC. I found an error saying that the was a IP address conflict for the IPv6 address. The error message was nice enough to tell me the MAC address for the other computer with the same address. When creating a Linux container a month ago i had given it the same IPv6 address as my domain controller. The DC refused then to use the address. That is why the DNS server could not listen to that address. I gave the container another IPv6 address. Restarted the DC. One computer that was still trying to be a DC succeeded. When i tried to promote another computer it also succeeded. 😀I know that an IP address conflict is bad. I am not surprised it created problems for the domain. The DNS and RPC requests went to the Linux container. It could not do anything. Windows then thought there was something wrong with the RPC server.