How can you prevent unauthorized devices from joining the network via wall ports?
Short answer
D NAC
Question
Key Takeaways
The key is to match the control to the threat: open wall ports allow rogue terminals to connect, and only NAC enforces authentication and posture checks before granting network access.
On the CompTIA Network+ N10-009 exam, security questions target physical network access controls. Community consensus for this question is 100% option D: NAC, because Network Access Control authenticates devices before they can use the network.
Common mistake: Some candidates choose ACLs because they think of restricting network access by rule, but ACLs operate after connectivity is established; they do not verify who is plugging in or whether that device is authorized.
Expert Analysis
Why the Answer Is Correct
D. NAC (Network Access Control) is the right technology for preventing visitors from accessing the corporate network through physical open ports. NAC can enforce 802.1X authentication, require endpoint posture checks, and place unauthenticated devices on a quarantine VLAN. As commenter [1] notes, even though users can still plug into the ports, they will not be authenticated and cannot use the network. Option D received 100% of the votes, aligning with CompTIA's focus on access control solutions.
Why the Other Options Are Wrong
A. URL filters only restrict web traffic, so they don't stop network-level access through wall ports. B. VPN is a remote access technique; it doesn't protect LAN switch ports from physical connections. C. ACLs filter traffic based on policies, but they don't authenticate devices and would not by themselves block every visitor. Only NAC combines identity, policy, and device health to prevent rogue access at the edge.
Community Comment Notes
The comments are unanimous on D, with users explaining that NAC controls access for people, machines, and everything in between [2]. One commenter succinctly states that NAC is the correct answer because it controls the network before access is granted [4]. No comment supported alternatives, reinforcing that the exam expects NAC whenever endpoint authentication and access policy are required.
Official Reference
https://datatracker.ietf.org/doc/html/rfc3580
This link opens the official vendor documentation in a new tab.
Exam Strategy
For security questions about unauthorized access, identify whether the issue is authentication of devices versus filtering traffic. NAC is the only option that checks the endpoint before allowing network entry; eliminate URL filters and VPN because they don't solve the threat from a physical wall port.
Community Votes
100% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 4 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 4
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BobbyCruz111 👍 5 Answered DNAC - Network Access Control. Even though the users can still plug into the ports they will not be authenticated to be connected and use the network
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HeatSquad77 👍 2 Answered DD. network access control (NAC) Control over information, people, access, machines, and everything in between
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chupapi_001 👍 2 Answered DThe correct answer is D. NAC (Network Access Control)
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kinkistyle 👍 1 Answered DNAC is the right choice
Reader comments & corrections
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