What protocol enables a manager to poll agents and access information from the agent MIB?

The protocol that allows a manager to poll agents and access information from the agent Management Information Base (MIB) is Simple Network Management Protocol (SNMP). SNMP is designed specifically for the management and monitoring of devices on IP networks.

When a network manager needs to gather information from managed devices, it utilizes SNMP to send requests to the agents residing on those devices. The agents then respond with the requested data from their MIBs. The MIB is essentially a database containing the parameters that can be monitored and controlled; it structures the data that SNMP can retrieve.

In contrast, the other protocols listed do not serve the same function in the context of network device management. ICMP (Internet Control Message Protocol) is primarily used for error messaging and operational queries such as ping, while TCP (Transmission Control Protocol) is a transport layer protocol that provides reliable communication; it does not directly facilitate polling of network devices. HTTP (Hypertext Transfer Protocol) is used for transferring web pages and is not inherently designed for network management tasks. Thus, SNMP stands out as the correct choice for enabling managers to poll agents and access their information effectively.