Hi all, I have a Windows 2003 Server Seecondary Dc and Exchange server 2003 on the same subnet. This Exchange Server usees the dc in that subnet. No issues so far. I am planning to decommission this DC and point the Exchange Server to the Primary Domain Controller in a different subnet. Is this a good Idea? The question I have is what would happen if for some reason Exchange cannot communicate with the PDC. Will authentication fail(Outlook and Outlook Web access) if PDC in unavailable? or will it continue to authenticate using the some sort of caching?

No there is no chaching mechanism on Exchange. The other problem is, that the complete Exchnge configuration is stored in Active Directory so if Exchange want´s to read the configuration e.g. during the start process and the DC ist not reachable than Exchange will bi in trouble. My decision would depends on the service level of my netork provider. But nevertheless if everything works on the network it is a good idee to reduce the number of DCs in order to reduce costs. regards Thomas Paetzold visit my blog on: http://sus42.wordpress.com

Thanks. This is what I needed to know.

Right now...how often and how fast does your DC communicate with the other DC?

Do you want to know the replication schedule? If it is they replicate once every one hour. how fast does your DC communicate with the other DC? -They are on the normal LAN.

Do you want to know the replication schedule? If it is they replicate once every one hour. how fast does your DC communicate with the other DC? -They are on the normal LAN. If this is the case, then you should be fine. Any Active Directory changes, Exchange will need to know about it.

Thanks for the input Jose.

You're welcome.