Recently my exchange servers hub transport unbale to start the services . It give event 1 , 2412 & 2501 for the ADtopology error and dns not register properly error.. performed nltest /dsgetsite .. receive error unable to get site name..However perform get-exchangeserver , you will be able to see the sites.Go to Active directory site & services , realise that there is one more sites created w/o any servers in the sites. No subnet was created as well . So decided to delete it .Wola ... everything back to normal...Question 1: Is the "get-exchangeserver" sites url is not the same as the nltest result ?Question 2: Why blank sites can affect the exchange topology services ? thanks

I would not think that an Exchange server in an unknown site would affect Active Directory connectivity. However, it would probably affect mail delivery. Exchange Server 2007 uses the Active Directory site architecture as a boundary between Hub Transport servers. Even if you have only a single site with servers, but multiple AD sites, defined, this might (well, apparently *did*) cause problems for the Exchange topology services.Why were sites defined that have no DCs or IP subnets associated with them? Jim McBee - Blog - http://mostlyexchange.blogspot.com