http://blogs.technet.com/isablog/archive/2008/07/13/isa-scripting-without-scripting-isa.aspxIntroduction ISA Server 2006 SP1 includes a fix released in September 2007 that allowed ISA 2006 arrays to use multicast and IGMP-aware Integrated NLB . Implementing this change is a four-part process: 1. Install the update (or preferably; SP1 ) 2. Runen-USCommunityServer 2.1 SP1 (Build: 61025.2)