Update (7/24): I updated this since the last revision, so if you downloaded it prior to 7/24/2018, get the newest version.
I began working with the product group on rolling in some of the network connectivity and testing checks available in the AAD Connect Network Test tool into the actual AAD Connect product. I look forward to getting more and more of the features added. Until then, I have added a few other checks:
- Forest Functional Level (Windows 2003+ required)
- Single-label domain (not permitted)
- NetBIOS name does not contain period (not permitted)
- AD Recycle Bin check (recommended)
You can pick up these whiz-bang new features at http://aka.ms/aadnetwork.