You may already that using "iisreset (server name) /restart" can restart IIS services on that remote server. But why such a command can give you this error message?

>iisreset myserver /restart

The RPC Server is unavailable.

I go ahead and turn off Windows Firewall on my server and now everything is fine. This reveals that actually iisreset was blocked by one of the rules.

Updated:

Actually DCOM related applications need more attention than I showed above. Please follow this article to set up DCOM port range and firewall rules.

http://support.microsoft.com/kb/217351