gethostbyaddr

string gethostbyaddr(string IP_address)

Gets the human-readable name for an IP address.

Returns:

Internet hostname; IP_address argument on error

Description:

gethostbyaddr() performs a DNS lookup of an Internet IP address and returns the corresponding domain name. If no name exists, the function returns the IP_address argument.

Availability:

UNIX, Windows

Version:

3+, 4+

See also:

gethostbyname() 
gethostbynamel()

Example:

23.5. Find the hostname for an IP address
<?php 
$ip = '18.29.1.31'; 
$host = gethostbyaddr ($ip); 

if ($ip != $host) 
   echo "The hostname for <i>$ip</i> is <i>$host</i>."; 
else 
   echo "I could not successfully look up <i>$ip</i>."; 
?>

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