A checklist for understanding each layer:
Layer 1: The Physical Layer:
_____1. Function of Layer 1
_____2. Transmission Type: Simplex/Half Duplex/Full
Duplex
_____3. T1, DS1 Super Frame, DS1 Extended Super Frame
_____4. Wireless Physical Layer
_____5. Wired Ethernet Physical Layer
_____6. Wireless PHY Analysis
_____7. Wireless Wi-Fi Layers
_____8. 802.11 Fundamentals, BSS, ESS, Standards
_____9. Wireless Operations, Beacons, Management
Frames
_____10. Wireless Data Capture
Layer 2: The Datalink Layer (Ethernet):
_____11. Ethernet Defined, Mechanisms and the OSI Model
_____12. Sublayers and Logical Link Control
_____13. Topologies
_____14. CSMA/CD and Full Duplex
_____15. Hubs and Switches
_____16. Ethernet Frame Formats
_____17. The MAC Address
_____18. ARP Protocol, Inverse, and Reverse ARP
_____19. Spanning Tree, RSTP Protocols
_____20. Ethernet Spanning Tree Analysis
_____21. VLANs and VLAN Trunking Protocol
_____22. Ethernet VLAN and VTP Analysis
Layer 3: The Network Layer —Internet Protocol (IP):
_____23. IP Protocol Functions, Format
_____24. IP Addressing, Reserved and Broadcast Addresses
_____25. IP Routing
_____26. Fragmenting Packets
_____27. IP Fragmentation
_____28. ICMP Protocol, Format, and Troubleshooting
_____29. ICMP Troubleshooting
Layer 4: The Transport Layer —TCP and UDP Protocols:
_____30. TCP Protocol Characteristics, Format
_____31. TCP Connection States
_____32. Three-Way-Handshake
_____33. TCP Sockets
_____34. TCP Segmentation
_____35. TCP Three-Way Handshake
_____36. Flow Control, Sliding Windows
_____37. Packet Loss, Re-transmission, and TCP Slow Start
_____38. Nagle Algorithm