Understand the web, one layer at a time
Go from a web address to a working mental model of DNS, connections, HTTP and caching. Each lesson includes an experiment and a reasoning check.
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Start the learning path ↗Before you begin
No account is required. Examples are educational, not instructions to alter a production system. Completion stays in this browser and does not issue a qualification.
THE PATH TO UNDERSTANDING
018 MINUTES
02How a name becomes a destination
Distinguish a successful name lookup from a working website.
8 MINUTES
03A page is more than one request
Explain why a successful document response can coexist with a broken page.
8 MINUTES
04What a protected connection does—and does not—prove
Keep transport protection separate from the trustworthiness of content.
8 MINUTES
When can a stored response be reused?
Distinguish cache storage from validation before reuse.