NSE4 High Availability and Diagnostics Practice Question
A FortiGate administrator receives an alert that the FortiGuard antivirus database on the firewall is outdated. Which subscription service must be active to update the antivirus signatures?
⚠ Common exam trap
NSE4 often tests whether candidates can map a specific FortiGuard update (AV, IPS, App Control, Web Filter) to the correct subscription service, since all four are bundled in UTM and candidates assume any active subscription updates everything.
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
✓
FortiGuard Antivirus Service
The FortiGuard Antivirus Service subscription is the specific entitlement that provides signature updates for the antivirus engine on a FortiGate. Without an active FortiGuard AV subscription, the FortiGate cannot download updated virus definition databases, which is exactly the alert described. Each FortiGuard subscription is licensed and updated independently, so only the AV service covers AV signature refresh.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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FortiGuard IPS Service
Why it's wrong here
The FortiGuard IPS Service maintains a separate signature database for intrusion prevention, detecting exploit attempts and network-level attacks in real time. It never supplies antivirus signatures for file-based malware scanning. An alert about outdated antivirus definitions is strictly tied to the AV service, not the IPS service, even though both are signature-driven. Therefore, choosing this service would address the wrong subsystem.
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FortiGuard Application Control Service
Why it's wrong here
FortiGuard Application Control Service focuses on identifying application traffic (e.g., social media, gaming, streaming) to enforce usage policies. Its signature updates contain application identity and protocol characteristics, not malware detection patterns. Antivirus signature updates are delivered independently under the FortiGuard Antivirus Service, so a problem with AV definitions is unrelated to application control. Thus, this option is incorrect because it targets a different FortiGuard module.
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FortiGuard Antivirus Service
Why this is correct
FortiGuard Antivirus Service is responsible for delivering up-to-date antivirus engines and virus signature files to the FortiGate, enabling scanning of files, email attachments, and web downloads for known malware. When the administrator sees an alert that antivirus signatures are outdated or failed to update, this is the subscription service to verify and troubleshoot. Without this service, the FortiGate cannot reliably block malicious content based on virus definitions. Therefore, it is the correct choice.
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FortiGuard Web Filtering Service
Why it's wrong here
FortiGuard Web Filtering Service provides URL/domain category classifications that permit or block web browsing based on content types (e.g., phishing, adult content). Its update channel contains URL categorisation and rating data, not antivirus signatures. Because antivirus signature updates use a distinct FortiGuard feed and license, a web-filtering outage would not cause antivirus signature update failures. Consequently, this option is incorrect as it addresses a different maintenance domain.
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Courseiva writes every NSE4 question from scratch — 773 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Fortinet exam blueprint
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.