PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

456 Chapter 20 Using Network and Protocol Functions
This is a simple form; the rendered version, with some sample data entered, is shown in
Figure 20.2.
Figure 20.2 Directory submissions typically require your URL and some
contact details so directory administrators can notify you when
your site is added to the directory.
When the submit button is clicked, you want to first check that the URL is hosted on a
real machine, and, second, that the host part of the email address is also on a real
machine.We wrote a script to check these things, and the output is shown in Figure
20.3.
Figure 20.3 This version of the script displays the results of checking the
hostnames for the URL and email address; a production version might
not display these results, but it is interesting to see the information
returned from the checks.
The script that performs these checks uses two functions from the PHP network functions
suite: gethostbyname() and dns_get_mx().The full script is shown in Listing 20.3.