Symptoms: updates are not being seen around the domain/forest. DC's will still authenticate users, but any changes (like password changes) will not replicated through the forest.
Run various commands for assisting in identifying the problem:
Dcdiag /test:dns /e /v >DnsHealth.log
/e = every DC in the forest
/v = verbose output
> DNSHealth.log = direct to file for easy study
Performs 6 tests - look for PASS/WARN/FAIL at the bottom of the LOG file.
nslookup example-cloud.com
Lists IP addresses of DC's in example-cloud.com – verify the correct number and address of DC's.
nslookup -q=srv _ldap._tcp.dc._msdcs.example-cloud.com
Look up DC service records - records are used to identify domain controllers for AD
REPADMIN is another command for identifying replication. For more details on REPADMIN visit http://technet.microsoft.com/en-us/library/cc755360(WS.10).aspx