Large Exchange Server Performance Tip

Posted By Chris Stinson in Exchange Server on June 5, 2007

Exchange server runs atop Active Directory on Windows. If underlying services are performing poorly, exchange server performance will suffer also.

Assigning a Specific Global Catalog Server to Exchange

Every time Active Directory needs to access the Global Address List (GAL) it queries the Global Catalog Server through LDAP. The default Global Catalog Server is the first domain controller deployed in the AD forest. The GCS holds all forest operations. If the GCS has other roles or services on it, it can get overloaded easily.

You can designate one or more domain controllers to act as Global Catalog Servers. Once you have done this, you can have Exchange use a specific GCS. If that server ever fails or is unreachable, it will use one of the other GCS’ available.

Go to Active Directory Sites and Services Console -> Sites -> Default First Site Name -> Servers -> Server of choice -> NTDS Settings -> Right-Click and select Properties.
Go to the General Tab and Select the Global Catalog checkbox. Click OK.
Open HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
MSExchangeDSAccess\Profiles\Default\UserDC1 on the Exchange Server. If it is not there, create it.
Create a REG_SZ value named HostName. Type in the fully qualified domain name (FQDN) of the global catalog server you wish to use.
Create a REG_DWORD value named IsGC. Assign a value of 0x1.
Create a REG_DWORD key named PortNumber. Assign a value of 0xCC4 or 0xCC5 for SSL. This is the LDAP port for accessing the GCS.
Relax and watch your Exchange Server run faster and more efficiently.