[Samba] net ads dns register question

[Henrik Zagerholm]

Hello,

First time using the new ads function and have some questions.
I'm issuing the command 5 times with different parameters and only  
one succeeds.

#net ads dns register
DNS update failed!

#net ads dns register -P
DNS update failed!

#net ads dns register -P -I 10.170.4.10
DNS update failed!

#net ads dns register -I 10.170.4.10 -U Administrator
Administrator's password:
Successfully registered hostname with DNS

#net ads dns register -I 10.170.4.10 -U Administrator%secret
DNS update failed!

net ads info
LDAP server: 10.170.4.10
LDAP server name: ad-server.foo.com
Realm: FOO.COM
Bind Path: dc=FOO,dc=COM
LDAP port: 389
Server time: Fri, 01 Jun 2007 21:17:57 CEST
KDC server: 10.170.4.10
Server time offset: -128

So the questions are:
Which DNS IP adress is the command targeting initially?
Why do I have to specify a user/password?
Why can't I specify a password together with the username so that I  
can script it?