An agent is described as software running on a managed device that communicates information via SNMP.

• A. An agent is software running on a managed device that communicates information via SNMP.
• B. A hardware device that routes traffic.
• C. A protocol for error detection.
• D. A database for storing user credentials.

Answer: (A)

In SNMP, the central idea is that devices expose management information through an agent. The agent is software running on a managed device, and it communicates information to the network management system using SNMP. It can respond to queries about various data points (MIB objects) and can also send notifications (traps) when events occur. This exactly describes a software agent that operates on the device and reports via SNMP.

The other descriptions don’t fit: a hardware device that routes traffic is a router, not an agent; a protocol for error detection is something like a checksum or CRC, not SNMP; and a database for storing user credentials is a credential store, not an SNMP agent.