Hello We are running Exchange 2003 and Exchange 2007 mixed mode. One forest, multiple domains. We have seperate CAS servers, but I also notice on Exchange 2003 servers, there is an option to set 'this is a front end server'. Does anyone know what selecting this option actually does? The reason I ask is that, from what I can see, even without ticking this box, an Exchange server can still provide OWA functionality etc. So, really, what is the definition of an FE and what does checking this box on an Exch server actually change on Exchange? Many thanks in advance.

That checkbox directs the server to proxy OWA for mailbox servers rather than redirecting it.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Hmm, not sure I completely understand...could you elaborate? :) Don't proxy and redirect effectively mean the same thing?

Redirect means that you have to connect to another URL to access OWA and your mailbox. Proxy means the OWA server you are connected to will handle the connection for you and no further action is required on the clients end.

Thanks. In which case, would the following statement be true... The server in question is Exch1.domain.com If the FE box is not checked, then OWA will only work if the mailbox is located on Exch1.domain.com. If someone enters http://exch1.domain.com/exchange for a mailbox that is NOT located on Exch1, then the OWA will not work. If the FE box IS checked, then the server will proxy the connection through to the correct mailbox server even if that mailbox is not Exch1? Am I thinking along the right lines here?

You cannot have mailboxes on a frontend server. Thus, if you connect to a server with mailboxes on it, but it isn't the server with YOUR mailbox on it, then Exchange will redirect you to the server with your mailbox on it. However if the server is a frontend server, then it will not redirect your connection, but will instead fetch the mailbox data for you. The most common scenario would to having to servers with the mailboxes on them (backend servers) and a single frontend server. The single frontend server allows a single URL for mailboxes on both servers. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources

Thanks, making sense now... Therefore, my current understanding: Server in question is Exch1.domain.com If the server is a FE and someone sends a request to http://exch1.domain.com/exchange, then the server will act as a proxy, that is - it will fetch the data from the relevant Exchange mailbox server and send back to the client. There is no changing of the URL. If the server is NOT a FE, then the server will change the URL (e.g. http://exch2.domain.com/exchange) to match that of the mailbox server. The client will then connect on that URL and the connection will be between the client and the other mailbox server. Exch1 is no longer involved? Am I correct? Finally, what happens if I have an Exchange server with mailboxes on it and I try and check the FE box? I don't have a lab server to test with, but I assume I would recv an error message? Thanks again for the great explanations.

It should also be noted that the redirection is to the server's REAL name. Therefore if the server's real name doesn't resolve on the Internet (and if you are using a .local internal domain it never can) then the connection will fail. This was an issue with Exchange 2003 that was corrected with Exchange 2007. I can't remember what happens if you try to make a server with mailboxes a frontend. It either doesn't let you, or blocks access to the mailbox. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources