update  [node node-id] session control -
        tower maintenance DECdns_fullname

    This command attempts to update the tower information in the
    DECdns namespace.  In order words, the node will attempt to
    ensure that the address information it is currently using is
    consistent with the address information present in the DECdns
    namespace.

    Under normal conditions the towers will be automatically updated
    whenever the Session Control Address Update Interval expires or
    whenever the node experiences an address change.

    Occasionally, automatic tower maintenance updates may fail.  For
    example, updates may fail if a DECdns server is not accessible.
    In that case, the DECNET_REGISTER or DNS$CONTROL tools might then
    indicate that the towers present in the DECdns namespace are not
    consistent with the towers currently in use by the node (as seen
    by ncl show addr).  In that case, you may issue this ncl update
    command to manually correct the inconsistency after the DECdns
    server becomes available again.

    If an OpenVMS node is configured to run DECnet over IP and the
    DECdns directory service is in use, IP towers will be maintained
    in addition to NSAP towers.  However, IP tower maintenance is
    handled differently than NSAP tower maintenance due to the fact
    that there will be a period in which the IP address will be
    0.0.0.0.  In that case, none of the node's IP towers will be
    updated in the DECdns namespace until DECnet over IP has
    finished initializing and the node has learned all of its IP
    addresses (i.e., no 0.0.0.0 address remains).

    Example:

    update session control tower maintenance DEC:.LKG.TRUE
        !  Attempts to update DNA$towers attribute of the
        !  DEC:.LKG.TRUE object in the DEC namespace with
        !  all of node TRUE's current address information.