(PHP 4, PHP 5, PHP 7) Get protocol number associated with protocol name

(PHP 5, PHP 7) Fetch DNS Resource Records associated with a hostname

(PHP 5 >= 5.4.0, PHP 7) Get or Set the HTTP response code

(PHP >= 5.3.0) Gets the host name string gethostname

(PHP 4, PHP 5, PHP 7) Alias of

(PHP 4, PHP 5, PHP 7) Checks if or where headers have been sent

(PHP 4, PHP 5 < 5.4.0) Initializes all syslog related variables

(PHP 5 >= 5.3.0, PHP 7) Remove previously set headers

(PHP 4, PHP 5, PHP 7) Send a cookie bool setcookie

(PHP 5 >= 5.1.0, PHP 7) Converts a packed internet address to a human readable representation