This problem occurs because the internal DNS server cannot resolve external DNS names for the Web request that the ISA server the Windows Essential Business Server server is requesting.
When the ISA server or the Windows Essential Business Server server receives a Web request from a client computer, the ISA server or the Windows Essential Business Server server tries to resolve the name of the requested Web site to an IP address. However, because the internal DNS server cannot resolve external DNS names, the request may take longer to process.
Note This problem may occur even if you have configured a routing rule in ISA Server or in Windows Essential Business Server.