Should you or shouldn't you have two Global Catalogs on a small network? Microsoft isn't very clear on this.

Posted on 2005-05-10
Medium Priority
Last Modified: 2010-04-14
We have a small network(windows 2000 server(2), exchange server 2000, and about 50 PCs. Server 1 has the exchange server and is the original server. It is also in charge of DNS & DHCP for our network. Server 2 came along as a result of needing to have a host for Backup Exec for windows servers and that's pretty much all that's expected of it. So, I wanted it to act as a backup top Server 1 in case of server 1's being down for maintenence or whatever. I have tried setting up replication between the two and am not convinced that I have succeeded with that. But as I'm reading the Help documents from Microsoft that pertain to the Active directory connector, I come across a prompt that says that the server I have selected for the connection (#2) is not a global catalog. and it "strongly" reccomends that the connection be made to a global catalog. So I begin a bit of searching in the help files regarding "global catalogs". I come across some info under the heading, "disabling" global catalog. It says that the global catalog is initiated by default and the "enable/disable" option can be found in the sites and services msc, under sites/server/ntds/properties. I looked and found that server 1 is enabled while server 2 is not. The help file states,


Do not enable this option unless you are certain it will provide value in your deployment. For this option to be useful, your deployment must have multiple domains, and even then, only one global catalog is typically useful in each site."

OK, we only have one domain so it makes me wonder if we don't need it. Reading further on in the same article it goes on to say,

"Clients must have access to a global catalog to log on, so you should have at least one global catalog in every site to receive the benefits of containing network traffic provided by using sites."

Now that sounds as if it's absolutely necessary if anyone ever hopes to log on. So far if server 1 goes down, no one can log on, I'm getting replication errors that make me question whether the replication is working (not to mention the inability to log on when server 1 goes down). So my question is: given the size of our site and the fact that we have only 1 domain & 2 servers, should I have both set to be global catalogs?
Question by:dwielgosz
  • 2
  • 2
LVL 18

Expert Comment

ID: 13968983
It is necessary to have a GC in order for your users to log onto the domain. So if server 1 goes down and server 2 is not a GC then even though it is a DC, your users won't be able to log on. So yes, it is a good idea to make both of your domain controllers GCs as well.

Also see this article:


Author Comment

ID: 13969122
So, if both are GCs, then if #1 goes down #2 will handle logons? As simple as that?
LVL 18

Accepted Solution

luv2smile earned 1500 total points
ID: 13969534
Pretty much atleast for a temporary time while you get your first DC back up. You should also run DNS on the second DC as well.

Author Comment

ID: 13969626
So as far as the #2 server and DNS is concerned, do I set DNS up to be identical to server #1 then?

Featured Post

Upgrade your Question Security!

Add Premium security features to your question to ensure its privacy or anonymity. Learn more about your ability to control Question Security today.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

NTFS file system has been developed by Microsoft that is widely used by Windows NT operating system and its advanced versions. It is the mostly used over FAT file system as it provides superior features like reliability, security, storage, efficienc…
If anyone asked you to network diagram of the internet, it was drawn in the form of a fluffy cloud which further became known as cloud computing. Popularly cloud computing is defined as workloads that run over the internet in a commercial provider’s…
Integration Management Part 2
Despite its rising prevalence in the business world, "the cloud" is still misunderstood. Some companies still believe common misconceptions about lack of security in cloud solutions and many misuses of cloud storage options still occur every day. …
Suggested Courses

850 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question