When you check the status of Active Directory replication between two domain controllers, you may see The RPC server is unavailable or The RPC server is too busy to complete this operation.
These error messages can be reported in the Event log through Active Directory Replication Monitor (Replmon.exe) from the Windows 2000 Support Tools, or Repadmin.exe from the Windows 2000 Support Tools.
The problem occurs because the time at each domain controller is beyond the skew allowed by Kerberos, preventing authentication.
If an authoritative time source is not available, you can use:
net time \\PDCFSMO /set /y
where PDCFSMO is the holder of the Primary Domain Controller (PDC) Flexible Single Master Operation (FSMO) role.
If you believe you have a configured time server, open a CMD prompt and type:
Here is a sample output that shows that PDCFSMO is configured but is not reachable:
W32Time: NTP: ntpptrs\[0\] - PDCFSMO
W32Time: rgbNTPServer PDCFSMO
W32Time: NTP: gethostbyname failed
W32Time: Port Pinging to - 123
W32Time: NTP: connect failed
W32Time: END:Line 1147</b>