Cool! Besides the solution you were shown involving adding one to the index before you print it, you could also use unshift to pad the array and work with its true index:

my @vdbhosts = sort @lines;
unshift @vdbhosts, 'padding';

my $count = 0;
for ( @vdbhosts ) {
    my $host = $vdbhosts[ $count ];
    print "$count: $host\n" unless $host eq 'padding';
    $count++;
}
[download]

Hope this helps!

Edit: added alternative solution example, my original reply didn't add much ;-)