DRAG DROP
You administer three Microsoft SQL Server 2012 servers named ServerA, ServerB, and ServerC.
ServerA is the acting principal and ServerB is the mirror.
You need to add ServerC as a witness to the existing mirroring session between ServerA
and ServerB. You need to achieve this goal without delaying synchronization.
Which three actions should you perform in sequence? (To answer, move the appropriate
actions from the list of actions to the answer area and arrange them in the correct order.)
Answer: 
On Serverc, Create an Endpoint for use by the witness
Ensure that the same windows login exists on each server and grant connect permissions to each server’s endpoint.
On ServerA, alter the principal database to use the endpoint on ServerC as the witness
Why this sequence though? You can get this question wrong by putting them in the wrong order, but how is ensuring the windows login existing on all servers wrong if it’s step 1? Seems like you should always start with making sure the pre-reqs are in place before doing anything.