my(%domains, $domain, @servers);
while (<IN>) {
  chomp;

  if (s/^# *//) {

    if (defined $domain) {
      $domains{$domain} = [ @servers ];
      @servers = ();
    }
    $domain = $_;

  } else {

     push @servers, $_;

  }

}

if (defined $domain) {
  $domains{$domain} = [ @servers ];
}