This Exchange TechNet Wiki article includes answers to some of the common questions around Exchange Schema versions that came from partners, customers and the community.

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Exchange Schema Versions

When preparing an Active Directory forest for the deployment of Exchange Server, one of the steps is to extend the Active Directory schema with new Exchange specific attributes and make modifications to existing schema classes and attributes.

Depending on the Exchange Server version (or Exchange service pack) used, the Active directory schema is extended with a different set of schema classes and attributes. The following table lists the Exchange schema version for each Exchange Server version and Exchange service pack released since Exchange 2000 RTM.
 

Exchange Version	Forest rangeUpper attribute of ms-Exch-Schema-Version-Pt	Forest objectVersion attribute of Organization container	Domain objectVersion attribute on Microsoft Exchange System Objects
Exchange 2000 RTM	4397	-	4406
Exchange 2000 SP3	4406	-	4406
Exchange 2003 RTM	6870	6903	6936
Exchange 2003 SP1	6870	6903	6936
Exchange 2003 SP2	6870	6903	6936
Exchange 2007 RTM	10637	10666	10628
Exchange 2007 SP1	11116	11221	11221
Exchange 2007 SP2	14622	11222	11221
Exchange 2007 SP3	14625	11222	11221
Exchange 2010 RTM	14622	12640	12639
Exchange 2010 SP1	14726	13214	13040
Exchange 2010 SP2	14732	14247	13040
Exchange 2010 SP3	14734	14322	13040
Exchange 2013 RTM	15137	15449	13236
Exchange 2013 CU1	15254	15614	13236
Exchange 2013 CU2	15281	15688	13236

Note
For information about available Exchange Server service packs and update rollups, see the Exchange Server and Update Rollups Builds Numbers TechNet Wiki page.

 

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What Changes are made to the Active Directory Schema when installing Exchange 2003, Exchange 2007 or Exchange 2010?

Each Exchange Server version adds a significant amount of Exchange specific attributes and makes modifications to existing schema classes and attributes. For detailed information around the specific changes for Exchange 2003, Exchange 2007 and Exchange 2010, see the Exchange Server Active Directory Schema Changes Reference document.

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How can I check the Exchange Schema Version in an Active Directory forest that holds an Exchange Organization?

After having installed a new Exchange Server version or Exchange service pack, it’s considered a best practice to verify the Exchange Schema version has been updated properly. This can be done by checking the value of the “rangeUpper” attribute found on the property page of the “ms-Exch-Schema-Version-Pt” schema attribute.

To lookup the value of the “rangeUpper” attribute, you can use a tool such as ADSI Edit, LDP.exe or DSQuery.

In order to lookup the “rangeUpper” value using ADSIEdit, log on to a Domain Controller in your Active Directory Forest and then click Start > Run and type “ADSIEdit.msc”. in the ADSI Edit console right-click on ADSI Edit in the navigation pane, then select “Connect to” in the context menu.

In the Connection Settings box, select Schema in the “Select a well known Naming Context” drop-down menu followed by clicking “OK”.

Now extend the schema node and then select “CN=Schema,CN=Configuration,DC=contoso,DC=com”. Then drill down and open the property page for the “CN=ms-Exch-Schema-Version-Pt” schema attribute.

On the property page, find the “rangeUpper” attribute and match the value with the table listed in the beginning of this article.

Using LDP.exe

If you want to look up the rangeUpper value using LDP.exe, log on to a Domain Controller in the Active Directory Forest, and click Start > Run and type “LDP.exe”. In the Ldp console, click Connection > Bind and then Bind as currently logged on user.

Then click “Tree” mode under “View” in the menu.

In the “Tree View” box, select “CN=Schema,CN=Configuration,DC=contoso,DC=com” in the drop-down menu.

Now expand the Schema node in the navigation pane, and then look up the “ms-Exch-Schema-Version-Pt” schema attribute. In the right pane, scroll down to the bottom where the “rangeUpper” attribute can be found.

Note
If the “ms-Exch-Schema-Version-Pt” schema attribute isn’t listed, you may need to increase the value of the “Max children” under Options > General in the menu.

Using DSQuery

If you want to look up the rangeUpper value using DSQuery, open a command prompt and type the following command:

dsquery * CN=ms-Exch-Schema-Version-Pt,cn=schema,cn=configuration,dc=domain,dc=local -scope base -attr rangeUpper

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Can I upgrade the Schema in an Active Directory that has Exchange 2007 SP3 Deployed to Exchange 2010 RTM?

This is not supported. In fact it’s not possible since the schema included with Exchange 2007 SP3 are newer than the one included with Exchange 2010 RTM. If you try to run “Setup /PrepareSchema” using the Exchange 2010 RTM bits in an Active Directory forest extended using Exchange 2007 SP3, the organization check will fail with the following error message:

Setup encountered a problem while validating the state of Active Directory: The Active Directory schema version (14625) is higher than Setup’s version (14622). Therefore, PrepareSchema can’t be executed.

Exchange 2010 SP1 or later should be used to upgrade the schema.

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Is it possible to extend the schema in an Active Directory Forest with Exchange Exchange 2007 SP1/SP2 with Exchange 2010 SP1 prior to upgrading to Exchange 2007 SP3?

Yes this is possible and a supported scenario as long as you only extend the Active Directory schema using “Setup /PrepareSchema” and do not prepare the Active Directory with “Setup /PrepareAD”.

Extending the Active Directory schema in a large organization is usually not an easy task. Because of this large organization would like to do a few Active Directory schema extensions as possible. If Exchange 2007 SP1 or Exchange 2007 SP2 is currently deployed in a large organization and the organization is planning to upgrade to Exchange 2007 SP2 or Exchange 2007 SP3, the organization could extend the schema using Exchange 2010 SP1 followed by preparing the Active Directory and domain(s) using Exchange 2007 SP2 or Exchange 2007 SP3 and then upgrading the Exchange 2007 servers to Exchange 2007 SP2 or Exchange 2007 SP3.

When the day comes where the organization is upgrading to Exchange 2010 SP1, the Active Directory schema wouldn’t need to be extended prior to preparing the Active Directory and domain(s) for Exchange 2010 SP1.

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Is it required to run "Setup /PrepapareAD" when upgrading from Exchange 2010 RTM or SP1 to Exchange 2010 SP2?

Yes Exchange 2010 SP2 requires the Active Directory to be prepared prior to upgrading any Exchange 2010 RTM or SP1 server in the respective forest. If you do not run "Setup /PrepareAD" prior to upgrading the first Exchange 2010 server, Exchange 2010 setup will, if the account used hold the necessary permissions, prepare the Active Directory automatically. 

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Testing in a Lab Environment is Key!

Although something is supported, it doesn’t mean that the scenario shouldn’t be tested in a lab environment mirroring the production environment.

When it comes to extending the Active Directory schema with Exchange specific attributes and classes, this is no different. When doing so, it’s also wise to test the Active Directory schema for extension conflicts. The steps on how to do so are outside the scope of this TechNet Wiki article. For details and required steps, see Testing for Active Directory Schema Extension Conflicts.

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External Links

•  Exchange Server Active Directory Schema Changes Reference, November 2011