- A
The relay destination is configured on the client-facing interface; it should be on the server-facing interface.
Correct: The 'ipv6 dhcp relay destination' command must be applied to the interface that receives client requests (client-facing), not the server-facing interface.
- B
The DHCPv6 server is not reachable via the relay agent's routing table.
Why wrong: Incorrect: While this could be an issue, the more common misconfiguration is the interface placement.
- C
The relay agent must have 'ipv6 dhcp server' configured to act as a server.
Why wrong: Incorrect: Relay and server functions are separate; a relay does not need server configuration.
- D
The clients are using DHCPv4, not DHCPv6.
Why wrong: Incorrect: The configuration is for DHCPv6, but the question states DHCPv6.
Quick Answer
The answer is that the relay destination is configured on the client-facing interface when it should be on the server-facing interface. This is because a DHCPv6 relay agent must forward client requests toward the server, meaning the `ipv6 dhcp relay destination` command must be applied on the interface that has a route to the DHCP server, not on the interface where clients are sending their solicit messages. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your understanding of DHCPv6 relay placement and the distinction between client-facing and server-facing roles; a common trap is assuming the relay command belongs on the same VLAN as the clients. The core concept is that the relay agent listens for client messages on one interface and then unicasts them out a different interface toward the server. A useful memory tip is "relay toward the server, listen from the client"—the destination address always points away from the client subnet.
300-410 DHCP (IPv4 and IPv6) Practice Question
This 300-410 practice question tests your understanding of dhcp (ipv4 and ipv6). 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.
A router configured as a DHCPv6 relay agent is not forwarding DHCPv6 requests from clients to the server. The relay interface has 'ipv6 dhcp relay destination' configured. Clients are on a different VLAN. Which is the most likely explanation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 relay destination is configured on the client-facing interface; it should be on the server-facing interface.
DHCPv6 relay requires that the relay agent has a route to the DHCP server. If the relay interface is not in the same VRF as the server, or if the server is reachable via a different interface, the relay may fail. A common edge case is that the relay destination is configured on the wrong interface (e.g., the client-facing interface instead of the server-facing interface).
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.
- ✓
The relay destination is configured on the client-facing interface; it should be on the server-facing interface.
Why this is correct
Correct: The 'ipv6 dhcp relay destination' command must be applied to the interface that receives client requests (client-facing), not the server-facing interface.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
- ✗
The DHCPv6 server is not reachable via the relay agent's routing table.
Why it's wrong here
Incorrect: While this could be an issue, the more common misconfiguration is the interface placement.
- ✗
The relay agent must have 'ipv6 dhcp server' configured to act as a server.
Why it's wrong here
Incorrect: Relay and server functions are separate; a relay does not need server configuration.
- ✗
The clients are using DHCPv4, not DHCPv6.
Why it's wrong here
Incorrect: The configuration is for DHCPv6, but the question states DHCPv6.
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 300-410 questions on switching, trunking, and access-port configuration.
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DHCP (IPv4 and IPv6) — study guide chapter
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FAQ
Questions learners often ask
What does this 300-410 question test?
DHCP (IPv4 and IPv6) — This question tests DHCP (IPv4 and IPv6) — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The relay destination is configured on the client-facing interface; it should be on the server-facing interface. — DHCPv6 relay requires that the relay agent has a route to the DHCP server. If the relay interface is not in the same VRF as the server, or if the server is reachable via a different interface, the relay may fail. A common edge case is that the relay destination is configured on the wrong interface (e.g., the client-facing interface instead of the server-facing interface).
What should I do if I get this 300-410 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 300-410 questions on switching, trunking, and access-port configuration.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Last reviewed: Jun 19, 2026
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.
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