How To Detect An Incoming Request (With PHP Script) From a CNAME Subdomain?

by

An important distinction to make is that a CNAME and a rewrite/redirect (or vhost) are totally different things that often get confused.

A CNAME is a DNS entity so that you can have multiple names pointing to a singular address. For example, bob.example.com is a host that lives at 1.2.3.4. You can then create a CNAME for alice.example.com which points to bob for DNS resolution and returns the same IP address.

A redirect is an HTTP method to take a request that lands on a certain location (http://bob.example.com/index.html) and returns an instruction to the browser to go somewhere else (http://alice.example.com/somewhereelse.html) which the client’s browser shows.

A rewrite is an HTTP method to take a request that lands on a certain location, change it, and then send it on to an answering server without necessarily letting the client’s browser know that it’s occured.

A virtualhost (vhost, etc…there are different names for the same function) is an HTTP method that allows you to answer a request in different ways by looking at the name that the request is using, often by examining the HTTP Host header that’s included in every request. Take the above for example: client requests http://alice.example.com, which resolves via DNS to 1.2.3.4 because alice is a CNAME to bob.example.com. The request lands on the same IP address, 1.2.3.4, but the web server that’s running there answers the request with the content under /alice instead of /bob.

Hope that helps

More Related Contents:

  1. Create subdomains on the fly with .htaccess (PHP)
  2. Change WordPress Admin URL
  3. how to redirect domain according to country IP address
  4. .htaccess – Redirect subdomain to folder
  5. Cannot modify header information [duplicate]
  6. Redirect all to index.php using htaccess
  7. HTTP authentication logout via PHP
  8. Htaccess: add/remove trailing slash from URL
  9. PHP Session timeout
  10. URL rewriting : css, js, and images not loading
  11. .htaccess rewrite GET variables
  12. Redirecting to previous page after login? PHP
  13. Deny direct access to all .php files except index.php
  14. .htaccess issues: No input file specified
  15. PHP built in server and .htaccess mod rewrites
  16. Rerouting all php requests through index.php
  17. PHP Header Redirect in a new window?
  18. Redirect after Login on WordPress
  19. .htaccess 301 redirect of single page
  20. Process HTML files like PHP
  21. How to redirect back to form with input – Laravel 5
  22. htaccess redirect all pages to single page
  23. How secure is HTTP_ORIGIN?
  24. What is the best way to notify a user after an access_control rule redirects?
  25. Using PHP/Apache to restrict access to static files (html, css, img, etc)
  26. laravel trailing Slashes redirect to localhost
  27. Permission denied: /var/www/abc/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable?
  28. How can I disable mod_security in .htaccess file?
  29. How can I create custom SEO-friendly URLs in OpenCart?
  30. How can I create custom SEO-friendly URLs in OpenCart?

Leave a Comment