Hm. You avoid cholera and get the pest. Not a good deal. I'd rather avoid creating and destroying an anonymous sub each time through a loop - so I'd write that as 

{
    my $subs = {
        num => sub { $a <=> $b },
        cmp => sub { $a cmp $b },
    };
    for ( qw{ NS MX TXT HINFO SPF SRV A CNAME PTR } ) {
        if ( exists $dns_records{$_} ) {
            print_header("$_");
            my $sortby = $subs->{ uc $_ eq 'PTR' ? 'num' : 'cmp' }; 
            for my $rec ( sort { $sortby->() } @{$dns_records{$_}} ) {
                print $rec, "\n";
            }
        }
    }
}

[download]

even if the optimizer would save my ass...

In reply to Re^3: Syntax question about closures and Perl 'sort' by shmem
in thread Syntax question about closures and Perl 'sort' by dwm042

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