Hello All, I have two different internet facing cas locations (Exchange 2010 SP2) and want to use a single global url (mail.domain.com) to access mailbox. I need to setup InternalURL and ExternalURL values for both CAS server location. I have idea as below but not sure will it work?? External DNS ISP 1 IP Address ISP 1 IP Address Host (A) mail.domain.com 202.1.1.1 mail.domain.com 303.1.1.1 Host (A) mail1.domain.com 202.1.1.1 mail2.domain.com 303.1.1.1 Internal DNS AD Site SiteA SiteB NLB Name noidanlb.domain.com 10.0.0.1 pthnlb.domain.com 20.0.0.1 CAS-InternalURL mail.domain.com 10.0.0.1 mail.domain.com 20.0.0.1 CAS-ExternalURL mail1.domain.com 10.0.0.1 mail2.domain.com 20.0.0.1 UserA with mailbox UserB with mailbox Case1: WAN link UP between SiteA and SiteB 1.In this case if userA access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteB, will userA redirect to SiteA for mailbox. 2. Similarly if userB access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteA, will userB redirect to SiteA for mailbox. Case2: WAN link DOWN between SiteA and SiteB 1.In this case if userA access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteB, will userA redirect to SiteA for mailbox. 2. Similarly if userB access his mailbox (from internet) via mail.domain.com and external dns hit goes to SiteA, will userB redirect to SiteA for mailbox. Thanks in advance NKumar