Which service should be configured to allow BIG-IP devices to be externally monitored?

SSHD provides secure shell remote CLI access for administrators, not a monitoring data feed for external systems.

TMSH (Traffic Management Shell) is the F5 command-line interface used for local or SSH-based administration, not an external monitoring protocol.

SMTP is a mail transfer protocol used for sending email, not for device health monitoring or metric collection.

SNMP is specifically designed for external monitoring, allowing network management systems (NMS) to poll BIG-IP devices for metrics such as CPU, memory, and traffic statistics via UDP port 161. On F5 BIG-IP, the SNMP agent must be enabled and configured with allowed manager IP addresses and community strings to permit external polling. This makes it the correct and standard choice for third-party monitoring integration.