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1.7. Reflection Checkpoint

Key Takeaways

Before proceeding, ensure you can:

  • Explain WHY networks use layered models (OSI/TCP-IP) and how layers enable troubleshooting
  • Distinguish between MAC addresses, IP addresses, and port numbers and explain when each is used
  • Describe the encapsulation process and identify the PDU at each layer
  • Apply the forwarding decision framework: switches use MAC addresses, routers use IP addresses

Connecting Forward

In Phase 2, you'll build on these foundations by examining the physical building blocks that implement these abstractions. The network components section directly applies the layer concepts—routers implement Layer 3 decisions, switches implement Layer 2 decisions, and understanding encapsulation helps you interpret frame and packet structures.

Self-Check Questions

  1. If a PC can ping its default gateway but cannot reach an internet website, which layers are working and which might have a problem?
  2. Why can a switch forward traffic immediately after power-on, while a router might need time before it can forward traffic?
  3. A packet travels from Host A to Host B through two routers. How many times do the source/destination MAC addresses change? How many times do the source/destination IP addresses change?