O365 AD Connector?

Hi Paul,

Whatever you do, do not take installing and configuring Azure AD Connect lightly!  I know (from experience, unfortunately) that one wrong checkbox can ruin your weekend, and possibly much longer than that.  You'll want to involve any other admins that run Microsoft services at your company, too, as once that sync is made there is no going back and it can greatly affect any and all Microsoft services in your environment.  

Make sure you understand all your options around https://docs.microsoft.com/en-us/azure/active-directory/hybrid/whatis-hybrid-identity before you decide how to set up your environment.  Additionally, make sure you review https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-syncservice-duplicate-attribute-resiliency - this is another one of those things that you can't undo once it is set.  And make sure that your https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-hybrid-identity-design-considerations-business-needs before going too far down that road.

Best of luck!