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Network Devices Cheat Sheet
Hubs, switches, routers, firewalls, and security appliances
| Device | OSI Layer | Function | Intelligence | Use Case |
|---|---|---|---|---|
| Hub | 1 (Physical) | Broadcast to all ports | None | Legacy, testing |
| Repeater | 1 (Physical) | Amplify/regenerate signal | None | Long cable runs |
| Bridge | 2 (Data Link) | Connect two segments | MAC learning | Legacy LAN segmentation |
| Switch | 2 (Data Link) | Forward by MAC address | MAC table | LAN connectivity |
| L3 Switch | 3 (Network) | Switch + routing | MAC + IP tables | Inter-VLAN routing |
| Router | 3 (Network) | Forward by IP address | Routing table | WAN, inter-network |
| Gateway | 3-7 | Protocol translation | Protocol-aware | Legacy system integration |
| Firewall | 3-7 | Filter traffic by rules | ACLs, stateful | Network security |
| NGFW | 3-7 | Firewall + DPI + IPS | App-aware | Modern perimeter security |
| IDS | 3-7 | Detect threats (passive) | Signature/behavior | Threat monitoring |
| IPS | 3-7 | Detect + block threats | Inline inspection | Active threat prevention |
| Load Balancer | 4-7 | Distribute traffic | Health checks | High availability, scaling |
| Proxy Server | 7 (Application) | Intermediate requests | Content caching | Web filtering, caching |
| WAP | 1-2 | Wireless access point | MAC, SSID | Wi-Fi connectivity |
| Wireless Controller | 2-3 | Manage multiple APs | Centralized config | Enterprise Wi-Fi |
| Modem | 1-2 | Modulate/demodulate signal | Signal conversion | DSL, cable, fiber |
| Media Converter | 1 | Convert media types | None | Fiber to copper |
| VPN Concentrator | 3 | Terminate VPN tunnels | IPsec/SSL | Remote access VPN |
🎯 Exam Key Points
- • Hub = Layer 1, broadcasts everything
- • Switch = Layer 2, uses MAC table
- • Router = Layer 3, uses IP addresses
- • L3 Switch = Switch + routing capability