How to Enable SNMP Monitoring of CPU and Memory on FortiGate
An admin wants to monitor CPU and memory usage on a FortiGate using SNMP. Which configuration is required?
Quick Answer
The correct answer is to enable the SNMP agent and configure an SNMP community on the FortiGate. This is required because the SNMP agent acts as the server-side process that listens for and responds to GET requests from a Network Management System (NMS), while the community string functions as a plaintext password for SNMPv1/v2c queries, granting access to monitor CPU and memory usage via specific OIDs like 1.3.6.1.4.1.12356.101.4.1.1 for CPU and 1.3.6.1.4.1.12356.101.4.1.4 for memory. On the Fortinet NSE 4 exam, this concept tests your understanding of foundational SNMP configuration rather than advanced trap or security settings—a common trap is assuming that simply enabling SNMP on an interface is enough, but without defining a community, the FortiGate will silently drop all SNMP requests. A useful memory tip: think of the community as the "key" that unlocks the SNMP agent's door—without both the door (agent) and the key (community), no monitoring data gets out.
⚠ Common exam trap
Many exam-takers confuse enabling SNMP on an interface (administrative access) with enabling the SNMP agent itself, leading them to select option C, which only allows SNMP traffic to reach the FortiGate but does not activate the SNMP service or community required for polling.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable SNMP agent and configure an SNMP community
To monitor CPU and memory usage via SNMP, the FortiGate must first have the SNMP agent enabled and an SNMP community configured. The community string acts as a password for SNMPv1/v2c queries, allowing an NMS to poll the device for OIDs like CPU usage (1.3.6.1.4.1.12356.101.4.1.1) and memory usage (1.3.6.1.4.1.12356.101.4.1.4). Without enabling the agent and defining a community, the FortiGate will not respond to SNMP GET requests.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure a performance SLA monitor
Why it's wrong here
Performance SLA is for link monitoring, not SNMP.
- ✓
Enable SNMP agent and configure an SNMP community
Why this is correct
Enabling SNMP agent and a community allows SNMP managers to poll OIDs for CPU/memory.
- ✗
Enable SNMP on the interface and set administrative access to SNMP
Why it's wrong here
Administrative access SNMP allows management via SNMP, but the SNMP agent must be enabled first.
- ✗
Configure an SNMP v3 user and enable SNMP traps
Why it's wrong here
Traps are for notifications, but polling CPU/memory requires SNMP agent enablement and community.
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Same concept, more angles
1 more way this is tested on NSE4
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator configures SNMP on a FortiGate to monitor CPU and memory usage. After applying the configuration, the NMS cannot reach the FortiGate via SNMP. The FortiGate's interface has SNMP access enabled. What is the most likely missing configuration?
medium- ✓ A.A firewall policy is missing to permit SNMP traffic from the NMS.
- B.The SNMP community string is not configured.
- C.NTP is not configured, causing time mismatch.
- D.The FortiGate is not configured to send SNMP traps.
Why A: The most likely missing configuration is a firewall policy to permit SNMP traffic from the NMS. Even though SNMP access is enabled on the interface, FortiGate uses firewall policies to control all traffic traversing between zones, including management traffic from an NMS. Without an explicit policy allowing UDP ports 161 (SNMP queries) and 162 (traps) from the NMS source to the FortiGate interface, the SNMP requests are dropped by the firewall.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE4 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE4 exam.