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Foundations: programming and problem solving · Novice · Lesson 14 of 98 · 39 min video, then about 5 hours of practice
How the web works: HTTP, DNS and the request-response cycle
After this you can explain what happens between typing a URL and seeing a page, including DNS, HTTP requests, status codes and responses.
Why it matters
Since this roadmap focuses on web software, you need a clear model of how a browser talks to a server. DNS turns a name into an address, the browser sends an HTTP request, the server sends back a response with a status code, headers and a body. Open your browser's network tab on a few websites and read the requests: method, URL, status, headers. Doing that ten times teaches more than any diagram. Trap: treating HTTP as plumbing you can ignore. Almost every web bug you will debug shows up first in a request or a response.
How to use this resource
Older but HTTP has not changed in the ways that matter here. Methods, status codes, headers, explained with live examples.
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