use strict;
use warnings;

print
   map { qq{@{ [ join q{.}, @$_ ] }\n} }
   map
   {
       my @quads = ( $_ );
       foreach my $part ( 0 .. 3 )
       {
           foreach my $offset ( reverse 0 .. $#quads )
           {
               next unless
                  $quads[$offset]->[$part] =~ m{(\d+)-(\d+)};
               splice @quads, $offset, 1,
                  map
                  {
                      my @quad = @{ $quads[$offset] };
                      splice @quad, $part, 1, qq{$_};
                      [ @quad ];
                  }
                  $1 .. $2;
           }
       }
       @quads;
   }
   map { [ ( split m{\.|\s} )[0 .. 3] ] }
   <DATA>;

__END__
172.17.119.2 # Comments are here...
172.17.119.4-5 # Comments are here...
172.19-21.254.2-3 # Comments are here...
192.168.1.1-3 # Comments are here...