Unit 4: DNS and HTTP.
In this unit, we describe the basics of DNS, and the HTTP protocol.
- DNS, described in CloudFlare blog. This is an excellent description of DNS, both in its normal version and its new encrypted one, and it is highly recommended reading.
- The HTTP protocol, used to transfer HTML pages. Required reading.
- HTTP error codes. The most important for us are:
- 200 OK
- 404 Page Not Found
- 500 Server Error – this means, you have to debug the error!
- 303 See Other – this is a redirect that will be instrumental in processing forms.
- 304 Not Modified – this means, the content was found in the cache.
- 403 Forbidden – this typically means an auth type error.