DCs and GCs

[bkirkflex]

One of our DCs when down today for a brief moment. During that time users where not able to log in. We have other windows 2000 servers "defined" as DCs. My question is do the other DCs contain a copy of the Global Catalog so that users can be authenticated? Or is there only one GC for users to be verified with?

Once the down DC came back up users could log in again. I would have thought that wnen a DC goes down in a domain with multiple DCs Users would still be able to log in.

Thanks

 

[Davetoo]

You have to enable the other server(s) to be GC's in AD Sites and Services. Go to the properties of the NTDS settings for one or more of your other DC's and enable them as GC's.

I'm Certifiable, not cert-ified.
It just means my answers are from experience, not a book.
The poster formerly known as lander215

 

[WhoKilledKenny]

A little more info. It is recommended that you have at least two GCs per-site within your domain....

 

[LWComputingMVP]

Actually, the recommended number of GCs varies with who you ask. MS MVP and widely reference Daniel Petri I've seen recommend only one GC per site. Personally, I recommend 2 GCs and 2 DCs for major sites, 1 DC/1 GC for minor sites (major meaning headquarters and sites with 30+ users or sites where down time is just not an option). This is for redundancy. More than 2 is RARELY needed. 2 DCs can handle thousands of logons and unless your at a site with 10,000+ users, more than 2 DCs can often just create replication traffic and not really do you much good.

 

[WhoKilledKenny]

Thanks LW but my recommendation is not base on how many logons a DC can handle, but redundancy of the GC. I would use one GC in a minor site if I knew that logon requests were not being blocked over the WAN link by an ACL. As far as replication, more than two DCs on a LAN should not cause any issues with traffic. The WAN is what you want to be mindful of, hence the configuration of your site topology to manage replication traffic....

my $.02

 

[bkirkflex]

Thanks everyone. I was thinking of two as well. We have 2 sites and only one GC. The are multiple DCs as I mentioned. So I was going to replicate the GC at the other site. What kind of overhead on the network will this entail initially? Probably want to start this process during the evening time when network traffic is low?

Thanks again.

 

[Davetoo]

No, you can do it anytime. The overhead won't even be noticed.

I'm Certifiable, not cert-ified.
It just means my answers are from experience, not a book.
The poster formerly known as lander215

 

[LWComputingMVP]

I would use one GC in a minor site if I knew that logon requests were not being blocked over the WAN link by an ACL.

I would think that's a given. You would define sites in sites and services and allow your other sites to be backups.