Active Directory is a directory service that is used by Microsoft Windows Server to manage user accounts, computers, and other resources in a network. Active Directory functional levels determine what capabilities of Active Directory Domain Services (AD DS) are available for a particular forest or domain.
Raising the forest functional level increases the capabilities of all domain controllers (DC) in the forest, increasing the Active Directory features available to the sysadmin. For example, Windows Server 2016 brought Privileged Access Management (PAM) functionalities along with all the functionalities of the previous version.
Why raise the forest functional level?
There are several reasons why you might want to raise the forest functional level:
- To gain access to new features and functionality. Raising the forest functional level gives you access to the latest features and functionality that AD DS has to offer.
- To improve security and compliance. Raising the forest functional level can help you to improve your security posture and meet compliance requirements.
- To support new applications and services. Some applications and services require a specific forest functional level in order to run properly.
What to consider before raising the forest functional level
There are a few things you need to consider before raising the forest functional level:
- All DCs in the forest must be running the same Windows server version as the forest functional level you intend to have, or higher.
- You must ensure that replication is working properly in your forest.
- You must verify that all your organization’s enterprise applications and services are compatible with the forest functional level you intend to have.
How to check the forest functional level
You can check the forest functional level by using the Active Directory Domains and Trusts console or by using PowerShell.
To check the forest functional level using the Active Directory Domains and Trusts console:
- Open the Active Directory Domains and Trusts console.
- In the left pane, right-click the domain node and select Properties.
- In the General tab, you will see the forest functional level listed under the Forest functional level section.
To check the forest functional level using PowerShell, run the following command:
Get-ADForest | fl ForestModeThis command will return the forest functional level.
Raising the forest functional level can give you access to new features and functionality, improve your security posture, and support new applications and services. However, it is important to consider the requirements before raising the forest functional level.
Next Steps
Once you have raised the forest functional level, there are a few things you should do next:
- Update all of your domain controllers to the new forest functional level.
- Update any applications or services that rely on AD DS to the new forest functional level.
- Test all of your applications and services to ensure that they are working properly with the new forest functional level.
You should also consider the following:
- If you have any domain controllers running an older version of Windows Server, you should upgrade them to the new forest functional level or demote them from domain controller status.
- If you have any read-only domain controllers (RODCs), you should verify that they are still replicating correctly with the new forest functional level.
- If you have any sites using slow WAN links, you should consider using a site link bridge to improve replication performance.
By following these steps, you can ensure that your Active Directory environment is running smoothly and securely at the highest possible forest functional level.
Raise Domain or Forest Functional Level First?
You need to raise the functional level of your Active Directory environment, but you’re not sure whether to raise the domain functional level first or the forest functional level first.
Raising the functional level of your Active Directory environment can be a complex and risky task. If you don’t do it correctly, you could experience downtime or other problems.
The general rule of thumb is to raise the domain functional level first, and then the forest functional level. This is because raising the domain functional level will make the domain compatible with the new forest functional level. However, there are some exceptions to this rule.
For example, if you have any domain controllers that are running an older version of Windows Server, you will need to upgrade them to the new forest functional level before you can raise the forest functional level.
Another exception to the rule is if you have any applications or services that rely on the domain functional level. If you raise the forest functional level before you raise the domain functional level, these applications and services may not work properly.
If you’re not sure whether to raise the domain functional level first or the forest functional level first, it’s best to consult with a Microsoft Active Directory expert.
Here is a table that summarizes the pros and cons of raising the domain functional level first and raising the forest functional level first:
| Action | Pros | Cons |
|---|---|---|
| Raise domain functional level first | – Minimizes the risk of downtime and other problems. – Ensures that all applications and services are compatible with the new forest functional level. | – May require upgrading older domain controllers. |
| Raise forest functional level first | – Allows you to use the new features and functionality of the forest functional level immediately. – May be required by some applications and services. | – Increases the risk of downtime and other problems. – May require additional steps to ensure that all applications and services are compatible with the new forest functional level. |
Accessible Functionalities According to Functional Levels
You want to know what features and functionality are available at each Active Directory functional level.
Choosing the right Active Directory functional level for your environment is important. Raising the functional level can give you access to new features and functionality, improve security, and support new applications and services. However, it is also important to be aware of the dependencies of Active Directory functional levels and the risks of raising the functional level.
The following table summarizes the key features and functionality that are available at each Active Directory functional level:
| Functional level | Key features and functionality |
|---|---|
| Windows Server 2016 | – Privileged Access Management (PAM) |
| – Nested domain support | |
| – Read-only domain controllers (RODCs) | |
| – Active Directory Recycle Bin | |
| – Windows Server 2012 R2 | |
| – Dynamic Access Control (DAC) | |
| – Device registration | |
| – Active Directory Federated Services (AD FS) | |
| – Windows Server 2012 | |
| – Active Directory Domain Services (AD DS) roles | |
| – Active Directory Administrative Center (ADAC) | |
| – Active Directory Rights Management Services (AD RMS) | |
| – Windows Server 2008 R2 | |
| – Active Directory Domain Services (AD DS) forest and domain functional levels | |
| – Active Directory replication | |
| – Active Directory groups and policies | |
| – Windows Server 2003 | |
| – Active Directory Domain Services (AD DS) directory | |
| – Active Directory users and computers | |
| – Active Directory groups and policies |
The specific features and functionality that are available to you will depend on the functional level of your Active Directory forest and domains. When choosing a functional level, it is important to consider your specific needs and requirements.
Best Practices for Raising the Forest Functional Level
Raising the forest functional level can be a complex and risky task. If not done correctly, it can lead to downtime or other problems. Therefore, it is important to follow best practices when raising the forest functional level.
Here are some best practices for raising the forest functional level:
- Plan and prepare. Before raising the forest functional level, it is important to have a plan in place. This plan should include the following:
- A list of all the domain controllers in the forest and their operating system versions.
- A list of all the applications and services that are running in the forest and their compatibility with the new forest functional level.
- A schedule for raising the forest functional level.
- Back up your data. It is important to back up all of your data before raising the forest functional level. This will allow you to recover your data if any problems occur.
- Update your domain controllers. All domain controllers in the forest must be running the same Windows server version as the forest functional level you intend to have, or higher. If there are any domain controllers running an older version of Windows server, you must upgrade them before raising the forest functional level.
- Verify replication. Replication must be working properly in the forest before you raise the forest functional level. You can use the Active Directory Replication Status Tool to verify replication.
- Test your applications and services. You should test all of your applications and services to make sure that they are compatible with the new forest functional level. You can do this by setting up a test environment and raising the forest functional level in the test environment.
- Raise the forest functional level. Once you have completed all of the above steps, you can raise the forest functional level. To do this, open the Active Directory Domains and Trusts console, right-click Active Directory Domains and Trusts, and select Raise Forest Functional Level.
- Monitor your environment. After raising the forest functional level, it is important to monitor your environment for any problems. You should check the event logs on your domain controllers and monitor the performance of your applications and services.
Next Steps
Once you have raised the forest functional level, there are a few things you should do next:
- Update your domain controllers. If you have any domain controllers that are running an older version of Windows Server, you should upgrade them to the new forest functional level.
- Verify replication. Replication must be working properly in the forest before you raise the forest functional level. You can use the Active Directory Replication Status Tool to verify replication.
- Test your applications and services. You should test all of your applications and services to make sure that they are compatible with the new forest functional level. You can do this by setting up a test environment and raising the forest functional level in the test environment.
- Monitor your environment. After raising the forest functional level, it is important to monitor your environment for any problems. You should check the event logs on your domain controllers and monitor the performance of your applications and services.
If you experience any problems after raising the forest functional level, you can contact Microsoft support for assistance.
Troubleshooting Problems After Raising the Forest Functional Level
Once you have raised the forest functional level, you should monitor your environment for any problems. If you do experience any problems, there are a few things you can do to troubleshoot the problem:
- Check the event logs on your domain controllers for any errors.
- Use the Active Directory Replication Status Tool to verify that replication is working properly.
- Test all of your applications and services to make sure that they are working properly with the new forest functional level.
- If you are unable to resolve the problem, you can contact Microsoft support for assistance.
Here are some specific troubleshooting tips for common problems that you may encounter after raising the forest functional level:
Problem: Unable to log on to domain controllers
Cause: The domain controllers may not have replicated the new forest functional level yet.
Solution: Wait for replication to complete, and try logging in again. If you are still unable to log in, you can manually force replication on the domain controllers.
Problem: Applications or services are not working properly
Cause: Applications or services may not be compatible with the new forest functional level.
Solution: Verify that the applications and services are compatible with the new forest functional level. If they are not compatible, you may need to upgrade the applications or services.
Problem: Replication is not working properly
Cause: There may be a problem with the replication topology or configuration.
Solution: Use the Active Directory Replication Status Tool to troubleshoot the replication problem.
If you are unable to resolve the problem using the above troubleshooting tips, you can contact Microsoft support for assistance.
Note: It is important to have a backup of your Active Directory environment before raising the forest functional level. This will allow you to restore your environment if you experience any problems.
FAQs
What are the risks of raising the forest functional level?
There are a few risks associated with raising the forest functional level:
- Downtime: If the forest functional level is not raised correctly, it can lead to downtime for your Active Directory environment.
- Data loss: If there are any problems with replication during the forest functional level raise, it can lead to data loss.
- Application compatibility issues: If any of your applications are not compatible with the new forest functional level, they may not work properly after the forest functional level is raised.
How can I troubleshoot problems after raising the forest functional level?
If you experience any problems after raising the forest functional level, there are a few things you can do to troubleshoot the problem:
- Check the event logs on your domain controllers for any errors.
- Use the Active Directory Replication Status Tool to verify that replication is working properly.
- Test all of your applications to make sure that they are working properly with the new forest functional level.
- If you are unable to resolve the problem, you can contact Microsoft support for assistance.
What are some additional resources to learn more about Active Directory functional levels?
Here are some additional resources to learn more about Active Directory functional levels:
- Microsoft Active Directory Functional Levels documentation:
https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels - TechNet article: Understanding and raising Active Directory functional levels:
https://technet2.github.io/Wiki/articles/16731.how-to-raise-the-forest-and-domain-functional-levels-in-windows-server-2008r2.html - White paper: Active Directory Functional Levels: A Guide to Understanding and Raising:
https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels
Conclusion
Raising the forest functional level can provide a number of benefits, such as access to new features and functionality, improved security, and simplified management. However, it is important to carefully plan and execute the forest functional level raise process to minimize the risk of problems.
By following the best practices outlined in this article, you can increase your chances of a successful forest functional level raise.
Here is a summary of the key points from this article:
- Before raising the forest functional level, make sure that all domain controllers in the forest are running the same Windows Server version as the forest functional level you intend to have, or higher.
- Verify that replication is working properly in your forest.
- Test all of your applications and services to make sure that they are compatible with the new forest functional level.
- Have a rollback plan in place in case something goes wrong.
- Raise the forest functional level during a maintenance window.
By following these steps, you can minimize the risk of problems and ensure a smooth transition to the new forest functional level.
