How many DC's should you have...

[bdoub1eu]

What's the rule of thumb when determining how many DC's to have in a domain. Obviously you need one at each location if you can...But is there a need to have two at each location for redundancy?

If you only have one server at a location and that server goes down, users will log in using another global catalog and Exchange 2003 will find another DC even if it is on a different subnet/location but in the same domain???

 

[PoliMalaka]

a lot of this will depand on how your networks are connected (if the routers will pass the information needed for this).
of course two DC's would be nice, but it depends on what the DCs are doing and how many users you have.
We have an AD with 25 sites and about 400 users at each.
Each site only has 1 DC. The authentication and lookups will failover to another DC on the WAN.

 

[bdoub1eu]

Thanks PoliMalaka!

We only have about 150 users and 3 locations...So right now, I have 2 DC's at each location so 6 total...

So you're saying the lookups would failover to a DC across the WAN if it needed to? Would exchange 2003 do the same for email?

Thanks!

 

[PoliMalaka]

Make sure your routers will pass the correct information.
For example a request for DHCP will not be passed by default on most router setups. You'll just have to test and make sure that the failover will work as hoped.