hardMultiple ChoiceObjective-mapped
300-410 Practice Question: Configures a DHCP snooping trusted port on a…
A network engineer configures a DHCP snooping trusted port on a switch to allow a legitimate DHCP server. However, clients connected to untrusted ports on the same VLAN cannot obtain IP addresses. The DHCP server is reachable and the switch shows no DHCP snooping drops. Which is the most likely explanation?
⚠ Common exam trap
Cisco often tests the misconception that DHCP snooping drops are always visible in the switch's drop counters, but the trap here is that the drops occur at the DHCP server, not the switch, so candidates may incorrectly focus on switch-side issues like VLAN mismatches or MAC verification.
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 DHCP server is not configured to trust the relay agent information option (option 82), causing it to discard the requests.
When DHCP snooping is enabled, the switch inserts the relay agent information option (option 82) into DHCP requests received on untrusted ports. If the DHCP server is not configured to trust or process option 82, it will discard these requests, preventing clients from obtaining IP addresses even though the switch reports no drops. This is the most likely cause because the DHCP server is reachable and the switch shows no drops, indicating the issue lies with how the server handles the relayed packets.
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 DHCP server is not configured to trust the relay agent information option (option 82), causing it to discard the requests.
Why this is correct
Correct: By default, DHCP snooping inserts option 82. Many servers reject packets with option 82 unless configured to trust it.
- ✗
The trusted port is in the wrong VLAN; DHCP snooping only works when the trusted port is in the same VLAN as the clients.
Why it's wrong here
Incorrect: The trusted port can be in any VLAN; DHCP snooping operates per VLAN.
- ✗
The switch has 'ip dhcp snooping verify mac-address' enabled, causing MAC address mismatches.
Why it's wrong here
Incorrect: This feature checks the source MAC in the DHCP packet against the Ethernet header, but the issue is about option 82.
- ✗
The DHCP server is not configured with the correct subnet for the client VLAN.
Why it's wrong here
Incorrect: This would cause server-side issues, but the symptom is that no clients get addresses, and the server is reachable.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.