my @list = ('10.1.1.1', '10.1.1.2', '10.2.2.1', '10.2.2.2');
@list = map { $_->[0] } 
        sort { $a->[1] cmp $b->[1] }
        map { [ $_, ''.reverse($_) ] } 
        @list;

use Data::Dumper;
print Dumper(@list);

__END__
output
======
$VAR1 = '10.1.1.1';
$VAR2 = '10.2.2.1';
$VAR3 = '10.1.1.2';
$VAR4 = '10.2.2.2';