Fixes for dynamic DNS update
    
    The current code assumed that only one server is given in the ipa_server
    config option and fails if multiple servers were given. To fix this
    nsupdate is first called without a server name assuming that nsupdate is
    able to find the name of the master DNS server of the zone by reading
    the SOA record. If this fails the IP address of the currently active
    LDAP server is used and nsupdate is called again.
    
    If there is no default realm given in /etc/krb5.conf nsupdate start
    trying to find a realm based on the DNS domain which might lead to wrong
    results. To be on the safe side the realm was added to the message send
    to nsupdate.