Changing Passwords

[Klaas Hagemann]

Hi,

we have set up a knew realm.
To get all the users in the realm, we told them to change their password.
Our passwortmanagement runs over a web-based php-applikation, which then
writes the password into kerberos.
The php-applikation uses kadmin with a host-Prinzipal and a keytab on the
host. There is only one prinzipal changing all the passwords or creating
principals for the user.
Now we have got sometimes users, where the passwort-changing does not work.
I have to possible ideas:

1: there are two or more users who want to change their passwd
simultaniously. What would happen, if one principal wants to change two or
tree passwords simultaniously?
2: these users uses bad passwords. I did not create any password policies,
but are there any conditions by default where a password would not be
accepted?

Any ideas?

Klaa