[Samba] Kerberos password question ( samba4 )

[miranda]

Hi you all
When doing a samba-tool  domain provision
we are asked to enter a password for administrator at OURDOMAIN
and later we use the same password to get a ticket when doing
kinit administrator at OURDOMAIN, ok ?

In my case i'm upgrading a samba3 with ldap box to samba4 using
samba-tool domain classicupgrade
My question is ? where is the password for administrator stored ?
Where does it came from ?

TIA
miranda