You can also do it like this to be a trifle more complete:

use Net::DNS; 
$res = new Net::DNS::Resolver;
warn "Net::DNS error $@\n" if $@;
# on some systems without the required config files you will need to
# direct Net::DNS to your DNS nameserver(s) or it will timeout
$res->nameservers( $prinary_nameserver_ip_address, $secondary... ) if 
+$res;

sub dns_query {
  return undef unless $res;
    my $domain = shift;
    $packet = $res->send($domain, 'MX') or warn $res->errorstring;
  return 1 if $packet->header->ancount;
    my $packet = $res->send($domain, 'A') or warn $res->errorstring;
  return 1 if $packet->header->ancount;
  return 0;             
}

print "OK DNS $domain" if dns_query($domain);
[download]

Kanji notes my slack duplication of identical code. It is more maintainable to do this:

sub dns_query {
  return undef unless $res;
    my $domain = shift;
    for my $dns ( 'MX', 'A' ) {
        $packet = $res->send($domain, $dns ) or warn $res->errorstring
+;
      return 1 if $packet->header->ancount;
    }
  return 0;             
}
[download]

cheers

tachyon

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