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Upgrading domain controllers to a newer Windows Server
Step 4 of 6 in Deploying domain controllers · video 3:34
What you will learn
- In-place upgrade versus adding new DCs and retiring old ones
- Why a clean installation is the recommended route
- When adprep /forestprep and /domainprep must be run by hand
- What must be true before raising the domain functional level
About this lesson
Moving a domain to a newer Windows Server release can be done in two ways: upgrade the operating system of the existing domain controllers in place, or add new domain controllers running the new version and retire the old ones. The lesson recommends the second route because it leaves a clean operating system and a clean AD DS database, and DNS records update so that clients find the new servers straight away. Before the domain functional level can be raised, every domain controller in the domain must run the new version. An in-place upgrade does not prepare the schema or the domain by itself, so adprep /forestprep and adprep /domainprep from the \support\adprep folder of the installation media must be run first. By contrast, promoting a new server into an existing domain while signed in as a member of Schema Admins and Enterprise Admins updates the schema automatically. The steps for both methods are listed, including pointing client DNS settings at the new domain controllers.
Check yourself
1. Which upgrade method does the lesson recommend, and why?
Adding new domain controllers on the new version and phasing out the old ones, because you end up with a clean operating system and a clean AD DS database instead of carrying old state forward.
2. What must you do before an in-place operating system upgrade of an existing domain controller?
Run adprep /forestprep and adprep /domainprep from the installation media, because an in-place upgrade does not prepare the schema and the domain on its own.
3. You promote a new server into the existing domain while signed in as a member of Schema Admins and Enterprise Admins. Do you need to run adprep first?
No. In this case the promotion updates the schema automatically, so a separate adprep run is not needed.
4. What happens if you try to raise the domain functional level while one domain controller still runs an older Windows Server version?
You cannot raise it. The domain functional level can go up only when every domain controller in the domain runs that version or later, so the old DC must be upgraded or removed first.
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