How many Global Catalog Servers are needed?

[Guest]

I’m new to Active Directory; and I just started testing a new domain I’ve
been working on. On one particular test, I started having issues that I
believe are related to Global Catalogs. Let me first give an overview of the
structure of the domain, and the test that I was trying to perform. Then I
will give the errors that I came across.

I have two offices. Office 1 is our production office. Office 2 is for our
Disaster Recovery. In office 1 we have 3 servers. 2 servers are Active
Directory Domain Controllers, and the third server is a member server used as
a File Server. Both Domain Controllers are both Active Directory Integrated
DNS Servers. There is a T1 line that connects both Office1 and Office2. In
Office 2, I have the same setup. I joined the first two servers to the same
domain in Office 1 as Active Directory Domain Controllers. These two servers
are also Active Directory Integrated DNS servers. The third server in Office
2 is also a member server used as a File Server. The File Server in Office 2
is only used at the moment for replication of the File Server in Office 1.
For this we are using a third party replication software. This setup was put
together this way in the event of a disaster and office 1 goes down, users
can go to Office 2 and work.

Here is the test I tried. I turned off both server 1 and server 2 in Office
1, hoping that Active Directory would still work because of Server 1 and
Server 2 in Office 2. The redundancy is there for the Domain Controllers and
for DNS. But after the server were down. I tried logging into the domain on a
pc as a user, and the logon took a long time. At the same time, he got into
his profile, but I don’t think his Group Policies were in affect. Then I got
an error. I forget what I was doing to generate it, but here it is.

"A Global Catalog cannot be located to retrieve the icons for the
member list. Some icons may not be shown."

Then in Office 2, I went into Users and Computers on Server 1 and tried to
open a Group Policy Object and got this error.

"Domain controller not found for domain.local" The Domain Controller for
Group Policy operations is not available. You may cancel this operation for
this session or retry using one of the following Domain Controller choices.
Here are the choices:
-The one with the Operations Master token for the PDC emulator.
-The one used by the Active Directory Snap-ins.
-Use any available Domain Controller.
OK or Cancel.
I Canceled.

Due to these messages, I believe the problem is due to a Redundancy of
Global Catalog Servers. I don't fully understand them. But my understanding
is that by default, Global Catalog is installed on the first Domain
Controller of a domain. Therefore I didn't install any additional and only
have one. How many should I have for redundancy?

Thanks in advance.

Shannon

 

[Philip Nunn]

Not sure the is the correct group for this topic, but anyways...the thoughts
that I have would be that your first 2 dc's in office 1 are the FSMO role
holders (the first DC you brought up probably is holding all the roles) you
would need to transfer or seize the roles to one of the DC's in office 2 to
have a functional active directory domain. DO NOT DO THIS in your
production environment though!!!!! I would create a new TEST domain and
setup a dc at office 1 and one at office two, then you could do a seize or
transfer of the fsmo role's to a new holder (office 2 dc).

Philip Nunn

 

[Raghuramji]

Hi,

The problem you specify here will not be due to global catalog
server.Check the log in the event viewer of the client machine where
you can get some clue.Otherwise send your logs for further analysis.

Raghuramji C
www.desktopcentral.com
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[Richard Oltmann]

If this is a single domain make all the domain controllers GC's users must
access a GC to logon to verify universal group membership. When you opened
group policy and gor the error it was due to the PDC emulator being offline.
THis FSMO should not be offline for very long
hope this helps
Richard