To determine what Domain Controllers are in your domain, run netdom query dc.
To determine whether there are any issues with replication between Domain Controllers, run repadmin /replsum.
If you want to test whether a domain controller is available, run nltest /dsgetdc:domainname.com
To check which Domain Controller you are authenticating against (connected to) run, set logon
For additional information about the currently logged on user run set u
To test DNS in your environment run dcdiag /test:DNS
For more extensive information use dciag /V
To check Windows Time Service use w32tm /query /status.
To determine WTS source use w32tm /query /source.
