CREST Practitioner Security Analyst (CPSA) Practice 2025 - Free CPSA Practice Questions and Study Guide

The correct answer is CDP, which stands for Cisco Discovery Protocol. It is a proprietary Layer 2 protocol developed by Cisco to facilitate the discovery of neighboring devices in a network. CDP operates at the Data Link layer of the OSI model, allowing devices to exchange information such as device IDs, IP addresses, software versions, and capabilities.

When a device running CDP is connected to the network, it periodically sends out CDP packets to identify its neighboring Cisco devices. Those devices, in turn, respond with their information, enabling the original device to build a comprehensive view of the network topology. This capability is especially useful for network management and troubleshooting, as it helps administrators understand how devices are interconnected.

Other protocols listed serve different purposes:

- VTP (VLAN Trunking Protocol) is used in managing VLANs across a network.

- HSRP (Hot Standby Router Protocol) is for providing redundancy in IP routers.

- STP (Spanning Tree Protocol) is used to prevent loops in network topologies.

CDP uniquely focuses on gathering and sharing information about neighboring devices, making it the correct choice in this context.