My AD environment consists of two W2k3 domain controllers, each a global catalog server, and an Exchange 2003 server. Recently one of my two domain controllers went down. This, in turn, brought my Exchange SMTP service to its knees.Application logson the Exchange server included: Process EMSMTA.EXE (PID=3972). All Global Catalog Servers in use are not responding: ... The Win32 API call 'DsGetDCNameW' returned error code [0x54b] The specified domain either does not exist or could not be contacted. The service could not be initialized. Make sure that the operating system was installed properly among other similar messages. Why did the other domain controller/gc not take over? What can Ido to keep this from happening again? Thanks

Hi,Directory Service Access (DSAccess) is a core component of Exchange 2000 Server and Exchange Server 2003 also DSAccess is capable of failover. In other words, if one of the global catalog servers or domain controllers that is being used by Exchange services were to fail, those services would continue to run by virtue of the fact that they would failover to use a different global catalog server or domain controller. However, if you are running Exchange on a domain controller, this failover will not take place; this is by design. This is one of the core reasons why its not necessarily a good idea to run Exchange on a domain controller.also have a look into below articles to have a clear picture.ReferencesTop support issues for the Exchange directory servicehttp://support.microsoft.com/kb/321318Directory service server detection and DSAccess usagehttp://support.microsoft.com/kb/250570/en-usTechNet Support WebCast: Understanding and troubleshooting DSAccess for Exchange Server 2003http://support.microsoft.com/default.aspx?kbid=910999A Closer Look At Directory Service Access (DSAccess) - Part 1 on MSExchange.orgA Closer Look At Directory Service Access (DSAccess) - Part 2 on MSExchange.orghope it helps

Hello, Can you post here the event log 2080 from application event log to this forum? You may change the server & domain name to hide identity. Event 2080 gives us basic idea about the DCs/GCs connectivity & AD topology detection to Exchange server and can be determine other things to troubleshoot issue if Exchange server is not installed ona DC. You can get detailed information about AD topology detection event 2080 here.... Event ID 2080 from MSExchangeDSAccess http://support.microsoft.com/kb/316300

Hi, Currently, we can try the following during the problematic time further. 1. Please try to ping the DCs from the Exchange server, and verify the result2. Try to telnet DC 3268/389 port from Exchange and verify.3. Run the netdiag /v >netdiag.txt on your Exchange server(netdiag included in support tool from Windows installation Disc) Thanks Allen

i've got the same problem and the outlook client don't login ..oasis in my heart