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 with SNI 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 EdgeYour code sends hundreds of requests a day through DNS, TLS, and HTTP layers you've never actually seen execute.
You're configuring systems you can't trace
You've set Cache-Control headers by copying Stack
Overflow answers without understanding freshness lifetimes. You've
debugged redirect chains without knowing why a 301 caches
permanently while a 307 preserves the request method. When AI
suggests TLS configurations or caching directives, you accept them
because tracing what each directive does at the protocol level feels
out of reach. These gaps don't announce themselves until they
surface as stale deployments, broken redirects, and hours of wasted
debugging in production.
See what happens between your code and the server
Each lesson includes a step-based visual simulation that makes invisible protocol mechanics visible.
Watch the Full Request Path
Trace DNS queries from OS cache through Root, TLD, and Authoritative name servers, then step through TLS 1.3 handshakes as they negotiate cipher suites and verify certificate chains in sequence.
Compare Protocol Versions in Action
See HTTP/1.1 head-of-line blocking, HTTP/2 multiplexed binary frames, and HTTP/3 independent QUIC streams execute so protocol tradeoffs become something you observe, not memorize.
Debug Caching Logic Step by Step
Walk through Cache-Control directive
evaluation, ETag-based conditional requests, and 304 Not
Modified responses to see exactly when the browser serves
cached content versus hitting the network.
What's Covered
Six lessons covering the complete lifecycle of a web request: from domain name resolution through encrypted handshakes, across three generations of HTTP, to the caching layer that decides whether the network gets involved at all.
Predict propagation delays and troubleshoot resolution failures by tracing the recursive lookup hierarchy and understanding TTL cache expiration mechanics.
Diagnose TLS connection failures and evaluate security configurations with a clear mental model of the 1-RTT handshake, SNI routing, and certificate chain verification.
Debug performance bottlenecks and make informed protocol decisions by understanding the progression from keep-alive connections to binary multiplexing to QUIC's independent streams over UDP.
Write correct caching headers and debug stale content issues
by understanding how freshness lifetimes, ETags, the
Vary header, and browser cache layers decide
what gets served.
The Curriculum
Comprehensive Lessons! Each with theory, interactive simulation, and quiz.
DNS Resolution and Record Mechanics
The hierarchical recursive resolution process from local OS cache to Root, TLD, and Authoritative name servers. The structural function of specific record types: A, AAAA, CNAME, TXT, MX (email routing), and NS (delegation). TTL countdown mechanics, cache expiration, and propagation delays.
The TLS 1.3 Handshake and SNI
The reduction from a 2-RTT to a 1-RTT handshake in TLS 1.3. Cipher suite negotiation and the ALPN extension. Certificate chain verification with intermediate CAs and expiration checks. SNI mechanics for routing multiple secured domains on a single IP, and the transition from asymmetric key exchange to symmetric bulk encryption.
HTTP/1.1 Semantics, Redirects, and Keep-Alive
The plaintext request-response cycle and header
composition. The behavioral distinction between 301,
302, 307, and 308 redirects, including method
preservation semantics and browser caching of permanent
redirects. Persistent connections using
Connection: keep-alive to avoid repetitive
TCP/TLS handshakes, and application-layer head-of-line
blocking.
HTTP/2: Multiplexing and Binary Framing
The translation of HTTP semantics into binary frames. Multiplexing concurrent request/response streams over a single TCP connection. Stream prioritization using the Extensible Priorities model (urgency and incremental signals), connection-level flow control, and the HPACK stateful header compression algorithm.
HTTP/3: QUIC and UDP Transport
The replacement of TCP with the QUIC transport protocol over UDP. TLS 1.3 integrated directly into the transport layer. Independent stream delivery resolving TCP head-of-line blocking. Connection ID tracking for migration across changing IP addresses, and session ticket mechanics for zero-RTT resumption.
HTTP Caching: Cache-Control, ETags, and Conditional Requests
The browser cache as the first checkpoint before any
network activity. Cache-Control directives:
max-age, no-cache,
no-store, must-revalidate, and
public versus private.
Freshness calculation from the Date header.
Conditional revalidation with ETags and
If-None-Match, and
Last-Modified with
If-Modified-Since. The 304 Not Modified
response. The Vary header for separate
cache entries. Browser cache layers: memory cache, disk
cache, and Service Worker cache. Cache-busting with
content-hashed filenames.
The working knowledge behind every web request, from DNS resolution to cached response
After this Deep Dive, you'll trace requests through DNS hierarchies, TLS handshakes, and HTTP protocol layers with the confidence to debug failures, evaluate AI-generated configurations, and make informed architecture decisions. When caching headers look wrong or redirect chains break, you'll know where to look and why.
Ready to see what's really happening?
All deep dives included with your subscription. Cancel anytime.