checkdnsrr

(PHP 4, PHP 5, PHP 7, PHP 8)

checkdnsrr — Check DNS records corresponding to a given Internet host name or IP address

Опис

checkdnsrr(string $hostname, string $type = "MX"): bool

Searches DNS for records of type type corresponding to hostname.

Параметри

hostname: hostname may either be the IP address in dotted-quad notation or the host name.
type: type may be any one of: A, MX, NS, SOA, PTR, CNAME, AAAA, A6, SRV, NAPTR, TXT or ANY.

Значення, що повертаються

Returns true if any records are found; returns false if no records were found or if an error occurred.

Примітки

Зауваження:
For compatibility with Windows before this was implemented, then try the » PEAR class » Net_DNS.

Прогляньте також

dns_get_record() - Fetch DNS Resource Records associated with a hostname
getmxrr() - Get MX records corresponding to a given Internet host name
gethostbyaddr() - Отримує назву хоста в інтернеті, відповідну до заданої IP-адреси
gethostbyname() - Get the IPv4 address corresponding to a given Internet host name
gethostbynamel() - Get a list of IPv4 addresses corresponding to a given Internet host name
the named(8) manual page

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User Contributed Notes 3 notes

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Krisztin Ferenczi ¶

11 years ago

criffoh at gmail dot com is right. Before you check domain, you must convert to ascii with idn_to_ascii function:
http://us2.php.net/manual/en/function.idn-to-ascii.php .

var_dump(checkdnsrr('ñandu.cl', 'A')); // returns false
var_dump(checkdnsrr(idn_to_ascii('ñandu.cl'), 'A')); // return true

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Martin ¶

8 years ago

Important Warning:

You need to add a dot to the end of the host name to make a fully qualified domain name.

To see why, try executing the following pieces of code:

$d1="gmail.con";
$d2="gmail.con.";
$r1=checkdnsrr($d1, "MX"); 
$r2=checkdnsrr($d2, "MX"); 
var_dump($r1);
var_dump($r2);

You will see that without the dot it claims that the domain "gmail.con" is valid.

Note that if you time the "checkdnsrr()" calls you will also see it takes longer without the dot because it treats it as a relative domain and does several tries based on the host name it is running on.

NB: in case you're interested, being treated as a relative domain explains what is happening. If your host is "example.com" the relative domain will eventually resolve to "gmail.con.com." which can be looked up, hence it wrongly claims "gmail.con" exists

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n at zay dot uk ¶

3 years ago

I always think you should state the blindingly obvious.
A function that contains checkdnsrr will return false without an internet connection.
So in a production environment you need an active internet connection to return a true result with a valid email address.

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