(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 < 5.4.0) Initializes all syslog related variables

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

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

(PHP 5 >= 5.4.0, PHP 7) Call a header function

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

(PHP 5, PHP 7) Alias of