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

The primary function of the SNMP (Simple Network Management Protocol) 'Trap' response is to asynchronously inform the manager of an event. In the context of SNMP, a trap is a type of message that is sent from an SNMP agent to an SNMP manager without being explicitly requested. This mechanism allows the agent to alert the manager about significant events or changes in device status, such as faults, changes in configurations, or breaches of predefined thresholds.

By using traps, the SNMP manager doesn't have to continuously poll devices for their status; instead, it can receive real-time notifications about important issues as they occur. This is particularly useful for maintaining network security and performance, as it allows for quicker responses to incidents and abnormalities.

The other answer choices do not align with the function of traps. Setting or changing values pertains to SNMP set commands, which are used to modify the configuration of a device. Retrieving a single value relates to SNMP get commands, which are designed to request specific data from managed devices. Therefore, the unique capability of traps to notify the manager automatically and without polling makes option B the correct choice.