samba - Jul 2010 - kerberos_kinit_password: preauthentication failed

Hi,
 
This is the first time i've tried to register a samba server to a domain 
(previously i've connected using another program, likewise, i think).
 
I've been following 
http://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/domain-member.html#id2571111
 
I got to the point where i've configured smb.conf [global]:
 
realm = domain.internal
workgroup = DOMAIN
password server = *
encrypt passwords = true
security = ads
 
I then ran net ads join -U administrator
 
And it said that it had successfully registered hostname to domain.internal  
(however, when I looked in AD it wasn't there, i take it it should have 
appeared after that step?)
 
It also said that it said it couldn't update the dns records, so i googled 
it and was told to enter my FQDN hostname against 127.0.0.1 in /etc/hosts.
 
I then realised that my hostname was wrong, so changed it in /etc/hostname 
and /etc/hosts, and restarted
 
then tried to rejoin the domain using net ads join -U administrator
 
It said:
 
kerberos_kinit_password newhostname$@domain.internal failed: 
Preauthentication failed
 
So i tried:
 
net ads join -U administrator -w domain.internal
 
and it didn't report any warnings or errors.
 
I'm just slightly confused, because the first time i ran "net ads join
-U
administrator" it went through fine, but when i ammended the hostname and 
ran it again, it errored with preauthentication failed, but "net ads join
-U
administrator -w domain.internal" went through with no errors.

Does it matter that the first time "net ads join -U administrator"
worked,
but the second time I needed "net ads join -U administrator -w 
domain.internal" for it to work?

Could anyone explain why it changed?

Thanks,

Matthew Millar


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