A network administrator needs to set up a network monitoring solution.

The correct answer is SNMP because Simple Network Management Protocol is commonly used to monitor network devices such as switches, routers, firewalls, servers, and wireless access points. SNMP supports community strings, especially in SNMPv1 and SNMPv2c, which function as basic authentication values. A read-only community string allows monitoring systems to collect device information without allowing configuration changes. This directly matches the requirement for read-only users and community-string-based authentication.

CompTIA Network+ N10-009 includes monitoring, management protocols, and operational tools as part of network operations. SNMP data can be collected by open-source monitoring platforms and displayed in dashboards for visibility into bandwidth usage, interface status, errors, CPU utilization, memory usage, and device availability.

TACACS+ is used for centralized authentication, authorization, and accounting, especially for administrative access to network devices. LLDP is a discovery protocol that helps identify neighboring devices but does not provide full monitoring dashboards. A SIEM collects and correlates security events, but community strings are not a SIEM feature. Therefore, configuring SNMP is the best answer.