The Web Request Journey: DNS, HTTP, and TLS
Trace a web request from the first DNS lookup to the final response — hierarchical DNS resolution, TLS 1.3 handshake and certificate verification, HTTP/1.1 keep-alive and redirect semantics, HTTP/2 binary framing and multiplexing, and HTTP/3 with QUIC over UDP and zero-RTT resumption.
See the Invisible
Interactive simulators visualise what's hidden from view.
Hands-On Labs
Step through executions tick by tick. Manipulate state.
Why, Not Just What
Understand the reasoning behind every design decision.
Quizzes & Cheatsheets
Verify your understanding and keep a quick reference handy.
Get Certified
Earn a shareable certificate to prove your deep expertise.
Become the Engineer Who Supervises AI
As AI generates more code, understanding what that code does becomes more valuable, not less. Someone must verify AI output, debug failures, and make architectural decisions.
Build Your Architectural EdgeThe space between a URL and a response is where your hardest bugs live
Guessing isn't debugging
You've waited out DNS propagation with no idea when records would actually update. Used a 302 redirect where a 307 was correct, silently losing POST data. Fixed TLS certificate chain errors by swapping files until the browser stopped complaining. AI now generates your server configs, CDN rules, and HTTP client code, and you approve it because it looks reasonable, not because you can trace what each header and directive actually does. The protocols your application depends on every second are the same ones you troubleshoot by guessing.
Watch invisible protocols run, step by step
Every lesson includes an interactive simulation that makes network mechanics visible.
Trace DNS resolution hop by hop
Follow queries from OS cache through Root, TLD, and Authoritative name servers, and see where TTL caching and expiration decisions happen at each level.
Step through the TLS 1.3 handshake
Watch the 1-RTT handshake unfold: cipher suite negotiation, certificate chain verification through intermediate CAs, and the switch from asymmetric key exchange to symmetric encryption.
Compare HTTP versions in motion
See HTTP/1.1 head-of-line blocking next to HTTP/2 multiplexed streams and HTTP/3's independent QUIC streams to understand why each protocol version exists.
What's Covered
The full lifecycle of a web request, from domain resolution to encrypted response delivery.
Trace recursive lookups from OS cache to authoritative servers and know why propagation delays happen after record changes.
Diagnose TLS handshake failures, read certificate chains, and verify SNI routing configurations without trial and error.
Pick the correct redirect code for every scenario, use persistent connections to cut latency, and spot where head-of-line blocking limits throughput.
Make informed HTTP version choices by knowing how multiplexing, QUIC transport, and zero-RTT resumption affect real request performance.
The Curriculum
Comprehensive Lessons! Each with theory, interactive simulation, and quiz.
DNS Resolution and Record Mechanics
The recursive resolution path from OS cache to Root, TLD, and Authoritative name servers. Record types (A, AAAA, CNAME, MX, TXT, NS) and their structural roles. TTL countdown mechanics, cache expiration behavior, and why DNS propagation takes the time it does.
The TLS 1.3 Handshake and SNI
The 1-RTT handshake in TLS 1.3, cipher suite negotiation, and the ALPN extension. Certificate chain verification through intermediate CAs, expiration checks, and SNI-based routing for multiple domains on a single IP. The transition from asymmetric key exchange to symmetric bulk encryption.
HTTP/1.1 Semantics, Redirects, and Keep-Alive
Plaintext request-response structure and header composition. The behavioral differences between 301, 302, 307, and 308 redirects, including method preservation and browser caching. Persistent connections via Connection: keep-alive, and application-layer head-of-line blocking.
HTTP/2: Multiplexing and Binary Framing
Binary frame translation of HTTP semantics and multiplexed concurrent streams over a single TCP connection. Stream prioritization with the Extensible Priorities model, connection-level flow control, and HPACK stateful header compression.
HTTP/3: QUIC and UDP Transport
QUIC's replacement of TCP over UDP with TLS 1.3 integrated into the transport layer. Independent stream delivery that eliminates TCP head-of-line blocking, Connection ID-based migration across network changes, and zero-RTT resumption through TLS 1.3 session tickets.
From DNS query to encrypted response, every hop accounted for
After this course, you'll trace full request lifecycles, diagnose failures at each protocol layer, and make informed decisions about HTTP versions, TLS configurations, and DNS record management. Whether you wrote the infrastructure code or AI did, you'll know what it does.
Ready to see what's really happening?
All deep dives included with your subscription. Cancel anytime.