SBS 2008: DCOM Error 10009

A Microsoft Small Business Server (SBS) 2008 server may log the following error in the System log:

Source: DistributedCOM
Event Id: 10009
DCOM was unable to communicate with the computer <Workstation>.<FQDN> using any of the configured protocols.

In addition, if you attempt to browse the workstation from the server (eg. Dir \\Workstation\c$) you receive:

Logon failure: The target account name is incorrect

However, you are able to browse the workstation via its IP address.

One reason for this issue is if there are IP address conflicts in the DNS Server database. This may occur if some machines have been away from the network (or switched off) for a period of time such that their IP address lease expires, another device has obtained that address in the meantime, but the original workstation continues to use the previous address once it returns to the network. Normally this would generate IP address conflict messages, but if the former device happens not to be on the network it won't create a problem for most networking operations. However the server may be confused trying to contact various machines for maintenance and reporting purposes.

To resolve:

1. On the server, delete all the lease records for the affected machines (or all machines) using the DHCP applet.

   If appropriate, extend the DHCP lease time to accommodate machines which may be off the network for lengthy periods.

2. On the server, delete all the records for the affected machines (or all machines) from the DNS Manager applet — take care not to remove the inbuilt records.

3. Reboot the affected workstations.

4. On the server, open an elevated command prompt and type:

   ipconfig /flushdns