#naive: O(N*logN)
my @sorted = sort {

	my @a = $a =~ /(\d+)\.(\d+)\.(\d+)\.(\d+)/;
	my @b = $b =~ /(\d+)\.(\d+)\.(\d+)\.(\d+)/;
	
	$a[0] <=> $b[0] || 
	$a[1] <=> $b[1] || 
	$a[2] <=> $b[2] || 
	$a[3] <=> $b[3]

} @unsorted;

#packed: O(N*logN)
my @sorted = sort {

	pack('C4' => $a =~ /(\d+)\.(\d+)\.(\d+)\.(\d+)/)
	cmp
	pack('C4' => $b =~ /(\d+)\.(\d+)\.(\d+)\.(\d+)/)

} @unsorted;

##</code><code>##

Benchmark: timing 5000 iterations of naive, packed...
     naive: 11 wallclock secs ( 9.91 usr +  0.32 sys = 10.23 CPU)
    packed:  8 wallclock secs ( 7.95 usr +  0.08 sys =  8.03 CPU)