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Hectal
Phase 7Intermediate8 of 8 in Networking

HTTP, HTTPS & Application Protocols

The protocol almost every service speaks: requests, methods, status codes, headers, cookies and sessions, caching, HTTP/1.1 vs 2 vs 3, how HTTPS and certificates work, and the other application protocols you'll meet (SSH, FTP, SMTP, IMAP, ICMP).

Phases 0–6 moved packets. This phase is about what's inside them for nearly every service you'll run: HTTP. Reading a raw request and response, knowing what each status code and header means, and understanding how HTTPS protects traffic are daily skills for anyone debugging APIs, load balancers, CDNs, or Kubernetes ingress.

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5 topics ~39 min 9 code blocks & diagrams
Start with the first topic
1
7.1

HTTP on the Wire: Methods, Status Codes & Headers

HTTP is a text conversation: the client sends a request line, headers, and an optional body; the server answers with a status line, headers, and a body. Read one raw exchange and every API, proxy, and load balancer becomes easier to debug.

8 min 1 diagram 1 code practice

2
7.2

Cookies, Sessions, Keep-Alive, Compression & Caching

HTTP itself remembers nothing between requests. Cookies and sessions add memory, keep-alive reuses connections, compression shrinks bodies, and caching headers decide who may store a response and for how long.

8 min 1 diagram 1 code practice

3
7.3

HTTP/1.1 vs HTTP/2 vs HTTP/3

Same methods, status codes, and headers; different transport. HTTP/2 multiplexes many requests on one TCP connection; HTTP/3 runs over QUIC on UDP to avoid TCP's head-of-line blocking and speed up connection setup.

7 min 1 code practice

4
7.4

HTTPS, Certificates & mTLS

HTTPS is HTTP inside TLS. TLS encrypts traffic and proves the server's identity with a certificate signed by a trusted Certificate Authority. Operationally, the main jobs are issuing, trusting, and renewing certificates before they expire.

8 min 1 diagram 1 code practice

5
7.5

SSH, FTP, SMTP, IMAP, ICMP & Forward Proxies

Beyond HTTP, a handful of protocols appear constantly in operations: SSH for remote access and tunnels, FTP/SFTP for file transfer, SMTP/IMAP/POP3 for email, ICMP for diagnostics, and forward proxies for controlled outbound traffic.

8 min 2 code practice