| Windows Server Version | Cluster Functional Level |
|---|---|
| Windows Server 2019 | 10.x |
| Windows Server 2016 | 9 |
| Windows Server 2012 R2 | 8 |
| Windows Server 2012 | 7 |
| Windows Server 2008 R2 | 6 |
| Windows Server 2008 | 5 |
| Windows Server 2003 R2 | 4 |
| Windows Server 2003 | 3 |
| Windows Server 2000 | 2 |
| Windows Server NT4 | 1 |