Check the status of the shared SYSVOL
dcdiag /test:netlogons
Verify DNS registration and functionality
dcdiag /test:dns
Verify communication with other domain controllers
nltest /dclist: <domain name>
Verify replication with other domain controllers
dcdiag /test:replications
Verify the availability of the operations masters
dcdiag /s: domaincontroller /test:knowsofroleholders /verbose dcdiag /s: domaincontroller /test:fsmocheck