hardMultiple ChoiceObjective-mapped
ISC2 CC Practice Question: A security auditor discovers that during a VLAN…
A security auditor discovers that during a VLAN hopping attack, a threat actor was able to send frames from a workstation on VLAN 10 to a target on VLAN 20. Which configuration flaw is most likely responsible?
⚠ Common exam trap
ISC2 often tests the distinction between VLAN hopping via DTP (trunk negotiation) and double-tagging attacks (native VLAN manipulation), so candidates may confuse the two and incorrectly choose the native VLAN option.
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
✓
Dynamic Trunking Protocol (DTP) is enabled on access ports
A VLAN hopping attack exploits the Dynamic Trunking Protocol (DTP) to negotiate a trunk link between the attacker's workstation and the switch. If DTP is enabled on an access port, the attacker can send DTP frames to form a trunk, allowing frames from VLAN 10 to be tagged and forwarded to VLAN 20. Disabling DTP on all access ports with the 'switchport nonegotiate' command prevents this attack.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Dynamic Trunking Protocol (DTP) is enabled on access ports
Why this is correct
DTP allows an attacker to negotiate a trunk and access other VLANs.
- ✗
The trunk port is set to native VLAN 1
Why it's wrong here
Native VLAN misuse is used for double-tagging attacks, but not the most common for this scenario.
- ✗
The switch is using default VLAN 1 for management
Why it's wrong here
VLAN 1 is a security concern but not directly related to VLAN hopping.
- ✗
Port security is not configured
Why it's wrong here
Port security limits MAC addresses but does not prevent VLAN hopping.
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Related to this question
Learn chapter
Introduction to Security Principles
Key term
Threat
A threat is any potential danger that could harm a computer system, network, or data, whether from a malicious hacker, a natural disaster, or an accidental mistake.
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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