Consider the scenario where we have URL Filtering enabled on TMG 2010 Server and it is not working.
A quick look at the Alerts section in TMG MMC shows:
The failure is due to error: A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider.
Description: An error occurred while trying to communicate with the Microsoft Reputation Service server. If this Forefront TMG server is chained to an upstream server, verify that the WinHTTP proxy is set to localhost. If this issue persists, check that Internet connectivity is available…”
Find out the cause and the fix over at:
DEBRA LITTLEJOHN SHINDER
MVP (Enterprise Security)