Network Models

Learn what network models are for, how requests move from name to response, and how to explain transport, routing, translation, TLS, and troubleshooting with disciplined language and evidence.

Start at the top, move stage by stage, then use practice and stage tests when you want a stronger check.

9 hours4 stages, 21 modulesBeginners welcomeFree, no account
Start with Module 1
Study setup - photo by John Schnobrich on Unsplash

What you will learn

  • Explain why reference models exist and when to use OSI vocabulary versus the operational Internet stack
  • Use correct protocol data unit names and describe encapsulation and decapsulation precisely
  • Distinguish names, IP addresses, MAC addresses, and ports by the jobs they actually perform
  • Trace a web request from URL to first byte, including DNS, transport setup, TLS or QUIC, and HTTP semantics
  • Explain TCP, UDP, QUIC, routing, NAT, and TLS with disciplined, source-aligned language
  • Use a repeatable troubleshooting method that turns symptoms into observables and safe next tests

Who this course is for

  • People who are new to networking and want a precise mental model instead of memorised slogans
  • Developers, operators, and security practitioners who need to explain real request behaviour clearly
  • Learners preparing for CompTIA Network+ N10-009 or Cisco CCNA 200-301 v1.1 who want stronger reasoning, not just flashcards

Prerequisites: None. The course starts from first principles and assumes only curiosity and willingness to be precise.

Course curriculum

Read the modules in order on the first pass. Use the practice and stage tests when you want a stricter check on what stuck.

1

OSI and TCP/IP foundations

8 modules · 3 hours

1What a network model is, and why engineers still use one24 min2Encapsulation and protocol data units24 min3How OSI maps to TCP/IP, and where the mapping breaks21 min4What each OSI layer actually does21 min5Names, addresses, ports, and what each one identifies21 min6Subnetting and local versus remote delivery21 min7From URL to first byte24 min8Foundations capstone: explain one request path clearly24 minPracticePractice testUntimedStage testStage test30 min
2

Applied TCP/IP behaviour

8 modules · 3 hours

9How TCP provides reliability and flow control24 min10How DNS resolution works in practice21 min11When UDP is the right choice, and how QUIC changes the picture21 min12How routing and forwarding really differ21 min13How NAT uses state, and why it breaks assumptions21 min14What TLS protects, and where it fits21 min15A repeatable method for troubleshooting requests24 min16Applied capstone. Diagnose a slow website without guessing27 minPracticePractice testUntimedStage testStage test30 min
3

Network models for security and operations

5 modules · 2 hours

17How to place security controls by layer21 min18Which observability signals actually help21 min19How to use packet captures safely and deliberately21 min20How segmentation reduces blast radius21 min21Practice capstone: when dashboards look healthy and users disagree36 minPracticePractice testUntimedStage testStage test20 min
4

Summary, revision, and practice

1 hour

A short recap stage for fast recall, scenario drilling, and a cleaner next-step plan.

Standards and references

This course is aligned to the following standards, frameworks, and certification objectives.

  1. 1ISO/IEC 7498-1 Open Systems Interconnection Basic Reference Model
  2. 2RFC 1122 and RFC 1123 Internet host architecture and application support requirements
  3. 3RFC 768 UDP, RFC 792 ICMP, RFC 8200 IPv6, RFC 9293 TCP, and RFC 9000, RFC 9001, and RFC 9002 QUIC transport and recovery
  4. 4RFC 1034 and RFC 1035 DNS, RFC 7766 DNS over TCP implementation requirements, and RFC 9499 DNS terminology
  5. 5RFC 8446 TLS 1.3 and RFC 9110, RFC 9112, RFC 9113, and RFC 9114 for modern HTTP semantics and transport variants
  6. 6RFC 2131 DHCP, RFC 4787 UDP NAT behavioural requirements, and RFC 5382 TCP NAT behavioural requirements
  7. 7CompTIA Network+ N10-009 official exam details and Cisco CCNA 200-301 v1.1 official exam topics
  8. 8NCSC Network Security Fundamentals plus NIST SP 800-207 Zero Trust Architecture and NIST SP 800-61 Rev. 3 incident response guidance where the course discusses segmentation and operational response