- A
DHCP snooping treats all ports as untrusted by default, except those explicitly configured as trusted.
Correct because DHCP snooping defaults all ports to untrusted to prevent rogue DHCP server attacks; only trusted ports (usually uplink to legitimate DHCP server) are configured.
- B
The ip dhcp snooping trust command is applied on ports connected to DHCP clients.
Why wrong: Incorrect because the trust command is applied on ports connected to DHCP servers, not clients. Client ports remain untrusted.
- C
DHCP snooping builds a binding database that maps client MAC addresses, IP addresses, VLAN, and port information.
Correct because the DHCP snooping binding table records client MAC, IP, VLAN, and port to prevent spoofing and ensure security.
- D
DHCP snooping can be configured globally without enabling it on specific VLANs.
Why wrong: Incorrect because DHCP snooping must be enabled on specific VLANs using the ip dhcp snooping vlan command; global enable alone does not activate it.
- E
DHCP snooping drops all DHCP packets that contain option 82 information from untrusted ports.
Why wrong: Incorrect because DHCP snooping drops DHCP packets from untrusted ports that do not contain option 82, or if the option 82 is present but inconsistent; the statement is too absolute and not fully accurate.
350-401 NAT and DHCP Practice Question
This 350-401 practice question tests your understanding of nat and dhcp. 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 two statements about DHCP snooping are true? (Choose two.)
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 treats all ports as untrusted by default, except those explicitly configured as trusted.
This question tests detailed knowledge of DHCP snooping operation and configuration, including trusted/untrusted ports and option 82.
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 treats all ports as untrusted by default, except those explicitly configured as trusted.
Why this is correct
Correct because DHCP snooping defaults all ports to untrusted to prevent rogue DHCP server attacks; only trusted ports (usually uplink to legitimate DHCP server) are configured.
Related concept
Access ports place end devices into a single VLAN.
- ✗
The ip dhcp snooping trust command is applied on ports connected to DHCP clients.
Why it's wrong here
Incorrect because the trust command is applied on ports connected to DHCP servers, not clients. Client ports remain untrusted.
- ✓
DHCP snooping builds a binding database that maps client MAC addresses, IP addresses, VLAN, and port information.
Why this is correct
Correct because the DHCP snooping binding table records client MAC, IP, VLAN, and port to prevent spoofing and ensure security.
Related concept
Access ports place end devices into a single VLAN.
- ✗
DHCP snooping can be configured globally without enabling it on specific VLANs.
Why it's wrong here
Incorrect because DHCP snooping must be enabled on specific VLANs using the ip dhcp snooping vlan command; global enable alone does not activate it.
- ✗
DHCP snooping drops all DHCP packets that contain option 82 information from untrusted ports.
Why it's wrong here
Incorrect because DHCP snooping drops DHCP packets from untrusted ports that do not contain option 82, or if the option 82 is present but inconsistent; the statement is too absolute and not fully accurate.
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.
Trap categories for this question
Command / output trap
Incorrect because the trust command is applied on ports connected to DHCP servers, not clients. Client ports remain untrusted.
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?
NAT and DHCP — This question tests NAT and DHCP — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: DHCP snooping treats all ports as untrusted by default, except those explicitly configured as trusted. — This question tests detailed knowledge of DHCP snooping operation and configuration, including trusted/untrusted ports and option 82.
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.
About these practice questions
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Last reviewed: Jun 18, 2026
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