Domain Functional Level Issues
For example if you raise the domain functional level to windows server 2012 you will not be able to promote a server that is running windows server 2008 to domain controller.
Domain functional level issues. I ve not heard of any known issue when raising the functional level to windows 2008 r2. Functional levels determine the available active directory domain services ad ds domain or forest capabilities. To prevent these issues from arising a new dc must be at the same level or greater than the functional level of the domain or forest.
Open active directory domains and trusts domain msc. The second restriction for which there is a limited exception on windows server 2008 r2 is that once upgraded the domain or forest functional level cannot later be downgraded. In this lab i had the domain and forest functional level set to server 2016.
Having compromised a windows domain one of the things i like to do that i think adds real. To reduce the risk you can refer to the best practices section of the following article before raising the functional level. In the left navigation pane right click the domain for which you want to raise the functional level and then click raise domain functional level.
Sign in to the domain controller holding the pdc emulator fsmo role. I was able to. The changes only add the aes hashes during the one dfl change from 2003 to any higher level 08 08r2 12 12r2 domain functional level.
When the domain functional level is raised it not possible to promote operating systems that are running earlier versions of the os. The underlying issue is due to the addition of the aes hashes 128 and 256 introduced. However functional levels do not affect which operating systems you can run on workstations and member servers that are joined to the domain or forest.
In 2003 functional level the kerberos key distribution centre kdc used either rc4 hmac 128 bit or des cbc md5 56 bit for kerberos encryption however when moving to 2008 domain functional level or higher you upgrade the key distribution centre kdc to use advanced kerberos encryption which uses aes 128 and aes 256 encryption. The raise domain functional level window appears. They also determine which windows server operating systems you can run on domain controllers in the domain or forest.