PHP MySQL - Stilson.net

www.it-ebooks.infoCHAPTER 16 • NETWORKINGSRV: Services record. Denotes the location of various services for the supplieddomain.TXT: Text record. Stores additional unformatted information about a host, such asSPF records.Consider an example. Suppose you want to verify whether the domain name example.com has acorresponding DNS record:This returns the following:The domain name existsYou can also use this function to verify the existence of a domain of a supplied mail address:if($valid)echo "The domain exists!";elseecho "Cannot locate MX record for $domain[1]!";This returns the following:The domain exists!Keep in mind this isn’t a request for verification of the existence of an MX record. Sometimesnetwork administrators employ other configuration methods to allow for mail resolution without usingMX records (because MX records are not mandatory). To err on the side of caution, just check for theexistence of the domain without specifically requesting verification of whether an MX record exists.Further, this doesn’t verify whether an e-mail address actually exists. The only definitive way tomake this determination is to send that user an e-mail and ask him to verify the address by clicking aone-time URL. You can learn more about one-time URLs in Chapter 14.333