This is a simple PHP that dns's a selected host or ip.

1. /*
2. Example by b0lt
3. This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
4. Example Name: dns.php
5. Tested On: PHP4  
6. Notes: Example is to learn from i supose.
7. */
8.  
9. <?php
10.  
11. ?>
12.  
13. <form method="POST" action="dns.php?info=lookitup">
14. <p align="center">Hostname:     <input type="text" name="dval" size="26">
15. <br><br>or<br>
16. <p align="center">IP:     <input type="text" name="dval1" size="26">
17. <br>
18. <br>
19. <input name="submit" type="submit" value="Submit">
20. </form>
21.  
22. <?
23.  
24. if(isset($info)) {
25.     if($info == "lookitup") {
26.         if(!$dval1 && !$dval) {
27.             echo "Error: You Left Both Forms Blank.";
28.             return;
29.         }
30.         if(!$dval) {
31.             $dlook1=gethostbyaddr($dvar1);
32.             echo "$dval1 resolves (Reverse-DNS's) to $dlook1";
33.             return;
34.         }   
35.     $dlook=gethostbyname($dval);
36.     echo "$dval resolves (DNS's) to $dlook";
37.     }
38. }
39. ?>