Hi,I got the answers in this forum and in Microsoft documentation that we should use unicast with CAS. Unfortunately, my network infrastructure (switches,firmware etc.)doesn't supportusing unicast.My question is:Is it supported by Microsoftto use multicast NLB on CAS servers? Thanks,

However this is recomendedto use unicast method for cas/hub NLB, but as per your limitation you can go through with multicast mode. http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part1.html http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part2.html http://www.msexchange.org/articles_tutorials/exchange-server-2007/high-availability-recovery/load-balancing-exchange-2007-client-access-servers-windows-network-technology-part3.htmlAnil

Would request a Microsoft representativeto suggest or confirm that running Exchange 2007 CAS with NLB in multicast or IGMP multicast is supported by Microsoft?Which means, after implementation If I'll log a call with Microsoft for any issue with Exchange, they shouldn't say that this configuration is not supported.Thanks,

Hi,Of course, that is supported.You can use NLB or a third-party hardware-based network load-balancing device for Client Access server.ThanksAllen