CCNP Security Practice Question
Which TWO of the following are valid methods to mitigate VLAN hopping attacks?
⚠ Common exam trap
Cisco often tests the misconception that simply using 802.1Q trunking (Option E) or setting the native VLAN to VLAN 1 (Option C) provides security, when in fact the key mitigations are disabling DTP on access ports and using an unused native VLAN on trunk ports.
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
✓
Disable Dynamic Trunking Protocol (DTP) on all access ports.
Disabling Dynamic Trunking Protocol (DTP) on all access ports prevents a switch port from automatically negotiating a trunk, which is the primary vector for VLAN hopping attacks. An attacker can spoof DTP messages to force a port into trunking mode, gaining access to multiple VLANs; disabling DTP eliminates this risk.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure switchport mode dynamic auto on all ports.
Why it's wrong here
Dynamic auto can negotiate trunk.
- ✓
Disable Dynamic Trunking Protocol (DTP) on all access ports.
Why this is correct
Prevents trunk negotiation.
- ✗
Set the native VLAN to VLAN 1 on all trunk ports.
Why it's wrong here
VLAN 1 is default and does not mitigate.
- ✓
Set the native VLAN to an unused VLAN ID on all trunk ports.
Why this is correct
Mitigates double-tagging VLAN hopping.
- ✗
Use 802.1Q trunking instead of ISL.
Why it's wrong here
Both are susceptible; switching encapsulation is not a mitigation.
Visual reference
About these practice questions
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco 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 350-401 exam.