Could someone point me...

[pippin_999]

No: HPFGUIDX 189515

Nikkalmati:
> 
> I didn't read the posts for several months after DH came out, so this is a real puzzle for me too.  DD is dead.  The school is not in session.  Has anyone been named to the post?  Didn't DD say the castle would recognize Snape, if necessary? 

Pippin:

Canon doesn't say, but since Snape and Dumbledore planned it all, I'm sure they wouldn't neglect giving  Snape a way to get into the castle and Dumbledore's office. McGonagall was acting head and she would have trusted Dumbledore's portrait, so it would have been easy for it to find out passwords and such and convey that information to Snape.

Also, Filch probably wouldn't believe that Snape had gone bad and would help him, and he knows several secret passages into the school.

I get the impression anyway that the castle's protective magic is less of a factor when school is not in session and there are no students in residence to protect. 

Pippin