- A
DHCP snooping is configured on a per-VLAN basis.
Correct because DHCP snooping is enabled on specific VLANs using the 'ip dhcp snooping vlan' command.
- B
DHCP snooping prevents all types of ARP spoofing attacks.
Why wrong: Incorrect because DHCP snooping alone does not prevent ARP spoofing; Dynamic ARP Inspection (DAI) is required for that purpose.
- C
The DHCP snooping binding database includes the client MAC address, IP address, lease time, VLAN, and port.
Correct because the binding database records these details for each DHCP lease obtained on a trusted port.
- D
Ports connected to DHCP servers should be configured as trusted ports.
Correct because trusted ports are allowed to send DHCP server messages (OFFER, ACK) and are typically connected to legitimate DHCP servers.
- E
DHCP snooping encrypts all DHCP traffic between the client and server.
Why wrong: Incorrect because DHCP snooping does not provide encryption; it only filters DHCP messages based on trust and builds a binding database.
350-401 Infrastructure Security Practice Question
This 350-401 practice question tests your understanding of infrastructure security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 statements about DHCP snooping are true? (Choose three.)
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
DHCP snooping is configured on a per-VLAN basis.
DHCP snooping is a security feature that filters untrusted DHCP messages. It builds a DHCP snooping binding database from trusted sources. Option A is correct because DHCP snooping is typically enabled on VLANs, not globally on the switch. Option C is correct because the binding database contains the client MAC address, IP address, lease time, VLAN, and port. Option D is correct because ports connected to DHCP servers are configured as trusted to allow DHCP server messages. Option B is incorrect because DHCP snooping does not prevent all ARP spoofing; that is the role of Dynamic ARP Inspection (DAI). Option E is incorrect because DHCP snooping does not encrypt DHCP traffic; it only filters messages based on trust.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DHCP snooping is configured on a per-VLAN basis.
Why this is correct
Correct because DHCP snooping is enabled on specific VLANs using the 'ip dhcp snooping vlan' command.
Related concept
Access ports place end devices into a single VLAN.
- ✗
DHCP snooping prevents all types of ARP spoofing attacks.
Why it's wrong here
Incorrect because DHCP snooping alone does not prevent ARP spoofing; Dynamic ARP Inspection (DAI) is required for that purpose.
- ✓
The DHCP snooping binding database includes the client MAC address, IP address, lease time, VLAN, and port.
- ✓
Ports connected to DHCP servers should be configured as trusted ports.
- ✗
DHCP snooping encrypts all DHCP traffic between the client and server.
Why it's wrong here
Incorrect because DHCP snooping does not provide encryption; it only filters DHCP messages based on trust and builds a binding database.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
Infrastructure Security — This question tests Infrastructure Security — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: DHCP snooping is configured on a per-VLAN basis. — DHCP snooping is a security feature that filters untrusted DHCP messages. It builds a DHCP snooping binding database from trusted sources. Option A is correct because DHCP snooping is typically enabled on VLANs, not globally on the switch. Option C is correct because the binding database contains the client MAC address, IP address, lease time, VLAN, and port. Option D is correct because ports connected to DHCP servers are configured as trusted to allow DHCP server messages. Option B is incorrect because DHCP snooping does not prevent all ARP spoofing; that is the role of Dynamic ARP Inspection (DAI). Option E is incorrect because DHCP snooping does not encrypt DHCP traffic; it only filters messages based on trust.
What should I do if I get this 350-401 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Last reviewed: Jun 18, 2026
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