Quick Answer
The answer is to disable unnecessary features and services, as this directly reduces the attack surface of IoT devices in a home automation network. By turning off unused ports, protocols, or remote access functions, you eliminate potential entry points that attackers commonly exploit, which is a foundational principle of device hardening. On the Certified Ethical Hacker CEH exam, this concept tests your understanding of the “reduce attack surface” phase in the security lifecycle, often appearing alongside network segmentation as a paired best practice. A common trap is assuming all default features are safe, but CEH emphasizes that manufacturers often enable insecure services for convenience. Remember the mnemonic “D.U.S.T.”—Disable Unused Services Thoroughly—to recall that every unnecessary feature is a liability in home automation security.
This CEH practice question tests your understanding of wireless, iot and cloud security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE of the following are best practices for securing IoT devices in a home automation network?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Enable Universal Plug and Play (UPnP) for easy integration.
Why wrong: UPnP introduces security risks.
Segment IoT devices on a separate VLAN or subnet.
Limits lateral movement.
Change default usernames and passwords.
Default credentials are easily exploited.
Disable unnecessary features and services.
Reduces attack surface.
Ensure all devices are connected directly to the internet for remote access.
Why wrong: Should use a secure gateway.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Segment IoT devices on a separate VLAN or subnet.
Segmenting IoT devices on a separate VLAN or subnet (Option B) is a best practice because it isolates potentially insecure IoT devices from the main trusted network. If an IoT device is compromised, the attacker cannot easily pivot to other devices on the primary LAN. This leverages Layer 2 or Layer 3 segmentation to enforce network access controls, reducing the attack surface in a home automation environment.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Enable Universal Plug and Play (UPnP) for easy integration.
Why it's wrong here
UPnP introduces security risks.
Segment IoT devices on a separate VLAN or subnet.
Why this is correct
Limits lateral movement.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Change default usernames and passwords.
Why this is correct
Default credentials are easily exploited.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Disable unnecessary features and services.
Why this is correct
Reduces attack surface.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Ensure all devices are connected directly to the internet for remote access.
Why it's wrong here
Should use a secure gateway.
Common exam traps
EC-Council often tests the misconception that UPnP simplifies integration and is safe, when in fact it is a well-known security risk due to its lack of authentication and automatic port forwarding.
Detailed technical explanation
VLAN segmentation works by assigning IoT devices to a separate broadcast domain, often using IEEE 802.1Q tagging on managed switches. In a home environment, this can be implemented with a router that supports multiple SSIDs or VLAN-aware access points, where inter-VLAN routing is restricted via ACLs. A real-world scenario is a compromised smart camera on the IoT VLAN being unable to reach a laptop on the main VLAN, preventing lateral movement even if the camera is fully controlled by an attacker.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
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FAQ
Wireless, IoT and Cloud Security — This question tests Wireless, IoT and Cloud Security — Read the scenario before looking for a memorised answer..
The correct answer is: Segment IoT devices on a separate VLAN or subnet. — Segmenting IoT devices on a separate VLAN or subnet (Option B) is a best practice because it isolates potentially insecure IoT devices from the main trusted network. If an IoT device is compromised, the attacker cannot easily pivot to other devices on the primary LAN. This leverages Layer 2 or Layer 3 segmentation to enforce network access controls, reducing the attack surface in a home automation environment.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CEH practice question is part of Courseiva's free EC-Council 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 CEH exam.
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