The target principal name is incorrect. Cannot generate SSPI context.

I was recently setting up a SQL Server 2014 AlwaysOn Availability Group when I got the following error message while attempting to add a Replica for the Availability Group via SSMS (SQL Server Management Studio) with Windows Authentication:

Interestingly enough, I could log into the SQL Server just fine using SQL Server Authentication, but the authentication was failing while using Windows Authentication.  Of course, for a SQL Server AlwaysOn Availability Group, I needed to use Windows Authentication, otherwise it wouldn't work!

Therefore, I did some research and it seemed that most of the issues regarding this issue dealt with problems regarding the domain.

I remembered that I had joined this particular server to the domain without first removing it from the domain.  From prior experiences, I remembered that this can cause problems if I re-join a computer to the domain with the same exact name. 

Therefore, I decided to do the following:

1. Leave the domain by joining a workgroup and rebooting the server
2. Deleting the computer object and all of its children (deleting the subtree) in Active Directory
3. Re-joining the server to the domain

Once I did that, I was able to successfully log into my other SQL Server using Windows Authentication to add it as a replica for my Availability Group!