samba - May 2013 - Weird issue when accessing a samba4 domain member by IP vs hostname

Hi all,

I seem to be posting a lot recently.

I have just set up an S4 member server to a S4 AD DC.

When trying to access from a windows XP client via \\xen-arch-s3-01 I 
get a username+password box which doesn't accept my credentials.
If I try to access via \\192.168.0.111 I get straight on, no questions 
asked.

Doing a loglevel 10 I see the following differences:

\\xen-arch-s3-01 log.smbd:  Got user=[qoole] domain=[XEN-ARCH-S3-01]
workstation=[R2-02]
len1=24 len2=24
log.smbd:  check_ntlm_password:  Checking password for unmapped user 
[XEN-ARCH-S3-01]\[qoole]@[R2-02] with the new password interface
log.smbd:  check_ntlm_password:  mapped user is: 
[XEN-ARCH-S3-01]\[qoole]@[R2-02]
log.smbd:  check_sam_security: Couldn't find user 'qoole' in passdb.
log.smbd:  check_ntlm_password: sam authentication for user [qoole] 
FAILED with error NT_STATUS_NO_SUCH_USER


\\192.168.0.111 log.smbd:  Got user=[qoole] domain=[SMC] workstation=[R2-02]
len1=24 len2=24
log.smbd:  check_ntlm_password:  Checking password for unmapped user 
[SMC]\[qoole]@[R2-02] with the new password interface
log.smbd:  check_ntlm_password:  mapped user is: [SMC]\[qoole]@[R2-02]
log.smbd:  check_ntlm_password: winbind authentication for user [qoole] 
succeeded
log.smbd:  check_ntlm_password:  PAM Account for user [SMC\qoole] succeeded
log.smbd:  check_ntlm_password:  authentication for user [qoole] -> 
[qoole] -> [SMC\qoole] succeeded

So, why does it think the domain is the hostname when connecting via 
said hostname?

Thanks,

Alex