yPass.net

How to look up an MX record:

require_once("Net/DNS.php");
$res = new Net_DNS_Resolver();
$res->debug = 1;
$answer = $res->search("example.com", "MX");
echo "<BR><HR><BR>";
print_r($answer);

This example will query the name server and output the following:

;; search(example.com, MX, IN)
;; query(example.com, MX, IN)

;; using extended PHP sockets

;; send_udp(208.79.80.18:53): sending 29 bytes
;; timeout set to 5 seconds
;; answer from 208.79.80.18:53: 90 bytes
;; HEADER SECTION
;; id = 46468
;; qr = 1    opcode = QUERY    aa = 0    tc = 0    rd = 1
;; ra = 1    rcode  = NOERROR
;; qdcount = 1  ancount = 0  nscount = 1  arcount = 0

;; QUESTION SECTION (1 record)
;;
;example.com.	IN	MX

;; ANSWER SECTION (0 records)

;; AUTHORITY SECTION (1 record)
example.com.		1800	IN	SOA	dns1.icann.org. hostmaster.icann.org. 2011062844 7200 3600 1209600 3600

;; ADDITIONAL SECTION (0 records)