Which statement accurately describes auto-MDIX on modern switches?

• A. It prevents collisions by default
• B. It eliminates the need for crossover cables between similar devices
• C. It requires a fiber optic link
• D. It sets default duplex automatically to full

Answer: (B)

Auto-MDIX automatically detects the type of copper Ethernet connection and swaps the transmit and receive pairs as needed. On modern switches, this means you can connect similar devices, such as switch-to-switch, with a straight-through cable and the link will form without requiring a crossover cable. That adaptability is what makes this feature so convenient.

It doesn’t have anything to do with preventing collisions by default, and it doesn’t require fiber optics—the benefit is specific to copper Ethernet cables. It also isn’t about setting duplex to full by itself; duplex negotiation is handled through auto-negotiation separately, while auto-MDIX handles the cable pair wiring.