According to Setspn Overview it's discouraged to use Setspn -A
to add an SPN record and it's suggested to use Setspn -S
instead.
It's said that Setspn -S
checks whether the SPN already exists before adding a new one. Setspn –A
does not perform this check.
Although you can use Setspn -A to add an SPN, you should use Setspn -S instead because -S will verify that there are no duplicate SPNs.
However on Windows Server 2012 I see that Setspn -S
and Setspn -A
behave the same way: if an SPN record for an account exists then I get a failure both with -A
and -S
arguments.
Is there any real difference between Setspn -S
and Setspn -A
?
Not any more. You sort of answered your own question. It has obviously been decided that there's no need for the original -A functionality of not checking for duplicates any more... but you can't just go willy-nilly ripping the -A out, because someone's script somewhere that was using -A would break.
Adding some official documentation to back up my claim:
http://technet.microsoft.com/en-us/library/hh831747.aspx