PHP get DNS Nameserver , Cname , MX , A records of a domain

PHP has a useful function called dns_get_record that can be used to get different types of records for a give domain , very easily.

These include the nameserver records, A records, CNAME records, MX records, SOA records etc.

The following examples are using the interactive shell, but you would use the function the same way in your php scripts.

1. Get Nameserver - NS Records :

The following example gets the nameserver records of a given domain name.

$ php -a
Interactive shell

php > print_r( dns_get_record('reddit.com' , DNS_NS) );
Array
(
    [0] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 21599
            [type] => NS
            [target] => ns-1029.awsdns-00.org
        )

    [1] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 21599
            [type] => NS
            [target] => ns-1887.awsdns-43.co.uk
        )

    [2] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 21599
            [type] => NS
            [target] => ns-378.awsdns-47.com
        )

    [3] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 21599
            [type] => NS
            [target] => ns-557.awsdns-05.net
        )

)
php >

2. A Record - IP address

The A record gives the ip address of the server where you would find the http server or other web services being hosted.

php > print_r( dns_get_record('reddit.com' , DNS_A) );
Array
(
    [0] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 252
            [type] => A
            [ip] => 151.101.193.140
        )

    [1] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 252
            [type] => A
            [ip] => 151.101.1.140
        )

    [2] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 252
            [type] => A
            [ip] => 151.101.65.140
        )

    [3] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 252
            [type] => A
            [ip] => 151.101.129.140
        )

)
php >

Another simple method to get the A record or IP address of a domain name is to use the function gethostbyname :

php > print_r( gethostbyname('reddit.com') );
151.101.129.140
php >

The above method returns only 1 ip address. If you want all the ip addresses then use the gethostbynamel method instead, which returns an array of ip addresses.

php > print_r( gethostbynamel('reddit.com') );
Array
(
    [0] => 151.101.129.140
    [1] => 151.101.65.140
    [2] => 151.101.1.140
    [3] => 151.101.193.140
)
php >

3. MX Record - Mail Server

MX Records give the mail server for a given domain. These mail servers can be used to send mails to a certain email on that domain say [email protected]

php > print_r( dns_get_record('reddit.com' , DNS_MX) );
Array
(
    [0] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 299
            [type] => MX
            [pri] => 1
            [target] => aspmx.l.google.com
        )

    [1] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 299
            [type] => MX
            [pri] => 10
            [target] => aspmx2.googlemail.com
        )

    [2] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 299
            [type] => MX
            [pri] => 10
            [target] => aspmx3.googlemail.com
        )

    [3] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 299
            [type] => MX
            [pri] => 5
            [target] => alt1.aspmx.l.google.com
        )

    [4] => Array
        (
            [host] => reddit.com
            [class] => IN
            [ttl] => 299
            [type] => MX
            [pri] => 5
            [target] => alt2.aspmx.l.google.com
        )

)
php >

For MX records there is an alternative function called getmxrr , which can be used like this :

php > getmxrr('reddit.com', $mxhosts);
php > print_r($mxhosts);
Array
(
    [0] => alt2.aspmx.l.google.com
    [1] => alt1.aspmx.l.google.com
    [2] => aspmx3.googlemail.com
    [3] => aspmx2.googlemail.com
    [4] => aspmx.l.google.com
)
php >

It returns an array of mxhosts for a given hostname/domain.

4. CNAME Records - Canonical Alias

php > print_r( dns_get_record('www.reddit.com' , DNS_CNAME) );
Array
(
    [0] => Array
        (
            [host] => www.reddit.com
            [class] => IN
            [ttl] => 281
            [type] => CNAME
            [target] => reddit.map.fastly.net
        )

)
php >

Conclusion

The dns_get_record method supports more options that provide dns records of other types.

Other options available include:

DNS_HINFO
DNS_PTR
DNS_SOA
DNS_TXT
DNS_AAAA
DNS_SRV
DNS_NAPTR
DNS_A6
DNS_ANY

Links and References :

1. Manual at : http://php.net/manual/en/function.dns-get-record.php