<Network-number><Host-number>

{<Network-number>, 0} and {<Network-number>, -1}

(a) the directed broadcast

       {<Network-number>, -1}

       {<Network-number>, 0}

     The network address itself {<Network-number>, 0} is an
     obsolete form of directed broadcast, but it may still be used
     by older hosts.

  (b) the link local (or limited) broadcast

       {-1, -1}

       {0, 0}

     The {0, 0} form of a limited broadcast is obsolete, but may
     still be present in a network.