Help: In detail.. exchange 2007 help!

I am wanting to know how exchange 2007 works with other domain controllers. We are planning on replacing one of4 DCs but this DC (i think) is no ordinary DC. This DC, specifies if exchange works or not, even though exchange is on a different server.

Basically, what i am wanting to know is, what services on servers does exchange need to run.

If i turn off the DC while exchange is still running, then OWA and outlook stop working. The DC is a global cateloge server and a DNS server. Thats all i think it does, as it was setup before i took over and no one left any specs on what the server did. I have moved the schema and domains and trust from this server to another server.

Can anyone help?

Thanks

Tim

Exchange will need to see a Global Catalog and internal users will need DNS for OWA to run.

I'm pretty sure that it's recommended that you don't put Exchange 2007 on a DC (if you can help it).

Thanks... but exchange is not sat on a DC and i have 2 other servers that are Global Catelog servers, but if i turn off that specific DC with a GC on, OWA doesnt work. Also, i have got a secondary DNS server so it should work. I have seen in Exchange that if you right click on Organisation Configuration and select modify Configuration Domain Controller you can specify a DC but is that to edit the whole Domain with???

I dont understand why it dont work?

Never needed to verify this is actually true, but Exchange heavily relies on AD[1] and I think it sticks to talking to whichever DC it settled on when the system started up. You just have to live with Exchange breaking if you take that DC down e.g. better to take Exchange down then the DC, and vice versa when starting up.

[1] Exchange needed one and used to have it's own local directory. I presume (don't know) a lot of that existing tech was reused for AD.

I think ive found it.

Running netstat, i found that the exchange server was only talking to one of the DCs. By clicking on Organisation Configuration and select modify Configuration Domain Controller and select the domain, i am now talking to other Domain controllers and GC servers.