On a typical Local Area Network (LAN), different computers are connected by a cable and a Network Interface Card (NIC). Which component completes each host’s physical/logical connection to the LAN medium?

Introduction / Context:
Every device on a Local Area Network (LAN) must physically and logically attach to the network medium (twisted-pair copper, fiber, or radio). The hardware component that performs framing, media access, and physical signaling for a host is the Network Interface Card (NIC), also called a network adapter. Understanding this role distinguishes NICs from WAN devices like modems or from generic cabling.

Given Data / Assumptions:

• The LAN uses cabling (e.g., Ethernet over twisted pair or fiber) or equivalent access medium.
• Each computer requires a hardware interface that implements Layer 1/Layer 2 functions.
• The question asks for the device that completes the LAN connection on the host side.

Concept / Approach:
The NIC presents a MAC address, implements Ethernet (or Wi-Fi) framing, and handles the physical encoding/decoding of signals. It connects to the LAN via a port (e.g., RJ-45 for copper or SFP for fiber) and interacts with OS drivers to send and receive frames. Without a NIC, a computer cannot participate on the LAN even if a cable is present.

Step-by-Step Solution:

Verification / Alternative check:
Device managers in operating systems list Ethernet/Wi-Fi adapters with drivers; removing or disabling a NIC prevents LAN participation. Network throughput counters and link status LEDs on NIC ports further demonstrate that the NIC is the essential interface between the host and the LAN medium.

Why Other Options Are Wrong:

• Modem: used for wide-area analog/digital adaptation, not LAN Ethernet connectivity.
• Special wires: cabling is necessary but not sufficient; needs an interface.
• Telephone lines: not the standard LAN medium; applicable to PSTN/DSL, not Ethernet LANs.
• Wireless access point: infrastructure device for Wi-Fi; the host still needs a wireless NIC to connect.

Common Pitfalls:
Confusing a switch port with the host adapter; assuming a USB-to-Ethernet dongle is not a NIC (it is—just external). Also, mixing up modem and NIC terminology in small-office contexts.

Final Answer:
Interface card