hardMultiple ChoiceObjective-mapped
ISC2 CC Practice Question: During a penetration test, an analyst discovers…
During a penetration test, an analyst discovers that a company's internal network has a switch configured with port security that allows only one MAC address per port. However, the analyst is able to plug a rogue device into a wall jack and successfully gain network access. What is the most likely weakness in this configuration?
⚠ Common exam trap
ISC2 often tests the misconception that 'port-security maximum 1' alone prevents any unauthorized device, but the trap here is that sticky MAC learning does not prevent MAC spoofing—it only restricts the number of unique MACs, not the identity of the device using that MAC.
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
✓
The switchport uses sticky MAC learning, and the attacker used a MAC spoofing attack to mimic an authorized device.
Port security with sticky MAC learning records the first MAC address seen on a port and then restricts access to that address only. However, if an attacker spoofs the MAC address of an already-authorized device, the switch sees the spoofed MAC as valid and permits access, bypassing the one-MAC-per-port restriction. This is a common bypass when sticky MAC is used without additional protections like 802.1X or MAC authentication bypass (MAB).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The administrator configured 'port-security maximum 1' but forgot to enable 'port-security' globally.
Why it's wrong here
If global port-security is not enabled, the command has no effect, but the configuration is present; this is less likely than MAC spoofing.
- ✗
The switchport security violation mode is set to 'shutdown' instead of 'restrict'.
Why it's wrong here
Shutdown mode would disable the port upon violation, not allow access.
- ✓
The switchport uses sticky MAC learning, and the attacker used a MAC spoofing attack to mimic an authorized device.
Why this is correct
Sticky MAC learns the first MAC; spoofing that MAC allows access.
- ✗
The switchport is configured as an access port but the rogue device is using a VLAN trunk.
Why it's wrong here
Trunking on an access port may be possible but port security still enforces MAC limits; not the primary weakness.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
Go deeper
Related to this question
Learn chapter
Introduction to Security Principles
Key term
Authentication
Authentication is the process of verifying that someone or something is who or what it claims to be before granting access to a system or resource.
Key term
Port security
Port security is a network switch feature that restricts which devices can connect to a port based on the device's MAC address, preventing unauthorized access.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.