My original post http://social.technet.microsoft.com/Forums/vi-VN/exchange2010/thread/7c478e90-3597-4e93-84c5-2a134c30c1e3 Any suggestions from Networking gurus.

Hi Customer, Please ensure your NLB use multicast mode and install path KB 960916. http://support.microsoft.com/kb/960916 In Blog, it need to add a static arp to default gateway, like 172.16.100.1. The issue has been resolved by above KB. http://blogs.technet.com/b/networking/archive/2009/01/15/unable-to-connect-to-windows-server-2008-nlb-virtual-ip-address-from-hosts-in-different-subnets-when-nlb-is-in-multicast-mode.aspxRegards, Rick Tan

Sorry Rick Tan for late reply.. Actually my exchange 2010 running on oprating system Windows 2008 R2 SP1 and patch 960916 is for Windows 2008.

Hi Customer, Do you reboot your server after patch 960916? If patch does not work, you could follow workaround way to resolve this issue.Regards, Rick Tan