"The zimbraAuthLdapURL attribute contains the URL of the Active Directory
server to bind to. This should be in the form:
ldap://ldapserver:port/
where ldapserver is the IP address or host name of the Active Directory server,
and port is the port number. You can also use the fully qualified host name
instead of the port number
."

FYI.
That last sentence doesnt seem to make any sense.