Which protocol is known as vendor-neutral for discovering neighboring devices on the LAN?

• A. LLDP (Link Layer Discovery Protocol)
• B. CDP
• C. UDLD
• D. STP

Answer: (A)

Discovering neighboring devices on a LAN in a way that works across different vendors is what this item tests. The best answer is LLDP, the standard defined as IEEE 802.1AB. It operates by exchanging structured data units called TLVs between adjacent devices, allowing switches, routers, and other equipment to learn each other’s identity, port information, and capabilities without relying on a single vendor’s technology. This compatibility makes LLDP ideal for network discovery, inventory, and topology mapping in mixed-vendor environments. By contrast, CDP is Cisco’s proprietary neighbor discovery protocol, while UDLD focuses on detecting unidirectional links and STP handles loop prevention rather than neighbor discovery.