In troubleshooting an Ethernet cabling issue, what is the first thing to verify?

• A. The devices are powered on
• B. The cables are terminated to the T568A or T568B standard
• C. The IP addresses are configured
• D. The network switch port LED status

Answer: (B)

Matching wire termination is essential for an Ethernet link. Ethernet relies on a specific pinout, and the two common termination schemes (same-standard on both ends) ensure the pairs line up correctly. If one end is terminated to one standard and the other end to the other, the wires are mismatched, so signals can’t traverse properly and no link forms—even with a good cable and connected devices. Verifying that both ends use the same termination standard catches and fixes this fundamental wiring issue at the start, which is why it’s the first thing to check in a cabling problem. While making sure devices are powered, IP addresses are correct, or the switch port shows a link is useful, those steps address power, addressing, and higher-layer status rather than the actual wiring.