[Samba] Samba bug or by design - browsing root

[Van_N_Ta at Keane.com]

Dear Technical Support,

We have a user who just accidentally mapped a network drive by entering
\\hostname\root and it worked eventhough root is not defined for sharing in
smb.conf file.  Now that we know, we are able to browse the root level on
the UNIX server just by keying in \\hostname\root from IE or Windows
explorer.  Is this a setting/configuration problem or by design for samba?
Is there a way to avoid this since we do want users to be able to browse
root (/).  Any help on this matter would be greatly appreciated.

I'm currently running on the following environment:
OS = DGUX R4.20MU06
Samba version = 2.2.8a

Thanks,

Van Ta