Networked Services: From Browser to Backend

Follow an HTTPS API request from a browser through name resolution, transport, TLS, HTTP, server code, and back.

Follow an HTTPS request from browser to service and watch its response return through the same system.

Walk one fresh HTTP/2 request over TCP from URL parsing through DNS, TLS, server handling, and the response.

Model one-way network links as a weighted directed graph and find when every reachable node receives a signal.

A practice prompt about the browser, network protocols, edge services, and application work behind a page load.

Design timeouts, retries, idempotency keys, and server-side state so a lost response does not silently duplicate an operation.

See how authentication, key lookup, atomic work, stored outcomes, and retry replay prevent duplicate create operations.

Follow a POST request from key validation through durable result storage so a lost response does not create a second resource.

Track the last accepted timestamp for each message and reason about state growth, ordering, and concurrent requests.

Trace SQL through parsing, logical rewrites, cost-based planning, physical operators, indexes, and the buffer pool.

Follow SQL through parsing and planning into scans, joins, buffers, visibility checks, and result rows.

Follow a selective SQL lookup through planning, a B-tree index, heap visibility checks, and the result rows.

Use EXPLAIN to predict scans and joins, then compare row estimates with execution observations on a safe SELECT query.

Understand why timeouts, retries, ordering, and consistency matter when remote machines can fail independently.

Follow a client command from the leader's log through replication, quorum commitment, state-machine application, and reply.