Scenario: We had set up an NLB cluster with two Windows 2008 servers. The purpose was to load balance the IIS sites hosted in these servers web01 and web02.A DNS entry was created pointing to the cluster IP, and the site was accessible using this DNS name. However, the site was not accessible from web01 was down, even with the clustering in place. Resolution: The problem was with the port rule setting.The filtering mode was set to " Multiple host " and affinity was set to " Single " . So all requests from our web browser will be handled only by a single host until the session is completed. This was causing all our queries to be redirected to web01, but it was down. In order to solve the issue, we set the affinity to " None ". This enables the client requests to be sent to all servers in the cluster during a session.