Network Connectivity Devices: Roles and Functions Across Network Architectures

1. Network Interface Card (NIC)

Operates at Layer 2 (Data Link), enabling physical and electrical connectivity. Embedded in most modern motherboards, NICs support speeds like 10/100/1000 Mbps and beyond in servers. Uses MAC addresses for communication and features link lights for status monitoring.

2. Hub

Layer 1 device that blindly forwards frames to all ports. Creates a shared collision and broadcast domain, resulting in inefficiencies in busy networks.

3. Bridge

Layer 2 device that connects two similar network segments, separating collision domains. Uses MAC addresses to filter traffic, reducing unnecessary transmissions.

4. Switch

Layer 2 device that intelligently forwards frames to specific ports based on MAC addresses. Each port has its own collision domain.

• Unmanaged Switch: Plug-and-play, no configuration
• Managed Switch: Configurable with VLANs, IP settings, QoS

5. Router

Layer 3 device that interconnects networks and selects optimal paths based on IP addresses. Separates broadcast domains and requires manual configuration of ports.

6. Firewall

Acts at multiple OSI layers (up to Layer 7), filtering traffic based on pre-defined rules. Can be hardware-based or software-implemented.

7. IDS/IPS

• IDS (Intrusion Detection System): Monitors and logs suspicious traffic
• IPS (Intrusion Prevention System): Actively blocks malicious packets
• HIDS: Host-based monitoring of logs and system events

8. Wireless Access Point (AP)

Layer 2 device connecting wireless clients to a wired network using analog signal conversion. Operates similarly to a hub within its collision domain.

9. Wireless Range Extender

Boosts AP coverage by receiving and retransmitting wireless signals. Requires a minimum of 15% overlap with the AP's coverage area.

10. Wireless LAN Controller (WLC)

Centralized management of multiple APs in large-scale wireless networks. Distributes configurations and directs user traffic into LAN.

11. DHCP Server

Automatically assigns IP addresses and related configuration to clients. Operates at the Application Layer via UDP ports 67 and 68.

12. DNS Server

Translates domain names into IP addresses. Critical for accessing network and internet resources. Uses UDP port 53 for queries.

13. Load Balancer

Distributes incoming traffic across multiple servers to prevent overload and improve fault tolerance.

14. Proxy Server

Intermediary that forwards client requests to other servers. Supports content caching and traffic filtering.

15. Modems

• Cable Modem: Transmits data over coaxial cable (DOCSIS standard)
• DSL Modem: Uses telephone lines for high-frequency data

16. Repeater

Layer 1 device that amplifies digital signals to extend network range.

17. Voice Gateway

Connects IP-based voice networks with public switched telephone networks (PSTN). Supports SIP and MGCP protocols.

18. Networked Devices

• VoIP Phones
• Printers with embedded NICs
• Access Control Systems
• Surveillance Cameras over IP
• HVAC Sensors on LAN
• IoT Devices (Ethernet/Wi-Fi/Bluetooth)
• ICS/SCADA Controllers

19. SOHO Network Segmentation

Improves bandwidth and performance by dividing large networks into smaller segments using switches and routers.

20. Environmental Considerations

• Temperature: Maintain with strong HVAC systems
• Humidity: 50% optimal to avoid corrosion or static discharge

21. Conclusion

A comprehensive understanding of connectivity devices—ranging from NICs to industrial controllers—is key for Network+ exam success and designing efficient, secure networks.