Question 1,711 of 2,152
DHCP (IPv4 and IPv6)hardMultiple SelectObjective-mapped

Prevent Cisco Router from Acting as DHCPv4 Server on a VLAN

This 300-410 practice question tests your understanding of dhcp (ipv4 and ipv6). Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 actions will prevent a Cisco IOS router from acting as a DHCPv4 server for a specific VLAN? (Choose TWO.)

Quick Answer

The answer is to disable DHCP snooping on the specific VLAN using the 'no ip dhcp snooping vlan <vlan-id>' command, or to apply the 'no ip dhcp server' command under the interface configuration. These two actions directly prevent the router from offering DHCP services on that VLAN because DHCP snooping acts as a per-VLAN filter for server messages, while the interface-level command explicitly stops the router from acting as a server on that link. On the Cisco CCNP ENARSI 300-410 exam, this question tests your understanding of how to granularly control DHCP server behavior without disabling the global 'service dhcp' process, which would affect all VLANs. A common trap is confusing 'ip dhcp excluded-address' or 'ip dhcp relay information trusted' with VLAN-level prevention—these do not stop the server from responding. Memory tip: think of "snoop or stop the port"—disable snooping on the VLAN or kill the server on the interface.

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

Configure 'no ip dhcp server' under the interface associated with the VLAN.

Option B is correct because configuring 'ip dhcp excluded-address' for the entire subnet of the VLAN prevents the router from offering any IP addresses in that subnet, effectively stopping it from acting as a DHCP server for that VLAN. Option E is correct because the global command 'no service dhcp' disables the DHCP server feature entirely on the router, which also prevents it from serving DHCP for the specific VLAN, albeit globally. Options A, C, and D are incorrect because they do not disable DHCP server functionality for the VLAN: A is not a valid command, C disables a security feature that does not affect the router's ability to serve DHCP, and D is used for relay agent trust, not server prevention.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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 'no ip dhcp server' under the interface associated with the VLAN.

    Why this is correct

    Correct. This command disables the DHCP server functionality on that specific interface, preventing it from responding to DHCP requests on that VLAN.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Configure 'ip dhcp excluded-address' for the entire subnet of the VLAN.

    Why it's wrong here

    Incorrect. The 'ip dhcp excluded-address' command only prevents the server from assigning those specific addresses; it does not stop the server from offering DHCP services on the VLAN.

  • Disable DHCP snooping on the VLAN using 'no ip dhcp snooping vlan <vlan-id>'.

    Why this is correct

    Correct. If DHCP snooping is enabled globally, disabling it on a specific VLAN prevents the router from acting as a DHCP server (since snooping is required for server operation in many deployments, but more accurately, disabling snooping on the VLAN stops the router from processing DHCP packets as a server on that VLAN).

    Related concept

    Read the scenario before looking for a memorised answer.

  • Configure 'ip dhcp relay information trusted' on the interface.

    Why it's wrong here

    Incorrect. This command is used to trust DHCP relay agent information (option 82) and does not affect the router's ability to act as a DHCP server.

  • Use the global command 'no service dhcp'.

    Why it's wrong here

    Incorrect. This command disables the DHCP server and relay agent globally on the router, affecting all VLANs, not just a specific one.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap is that candidates might think 'no ip dhcp server' under interface works to disable DHCP on a specific interface, but such a command does not exist. Also, disabling DHCP snooping does not stop the router from being a server; it actually makes it easier for rogue servers to operate. The correct methods are to exclude the subnet or disable the server globally.

Trap categories for this question

  • Command / output trap

    Incorrect. The 'ip dhcp excluded-address' command only prevents the server from assigning those specific addresses; it does not stop the server from offering DHCP services on the VLAN.

Detailed technical explanation

How to think about this question

The 'no ip dhcp server' interface command is a per-interface override that stops the DHCP server process from listening on that interface, effectively isolating the VLAN from DHCP services without affecting other VLANs. DHCP snooping, when enabled, builds a binding database of legitimate DHCP clients and servers; disabling it on a VLAN removes the trust and validation mechanisms, causing the router to drop DHCP server messages on that VLAN. In real-world scenarios, this is useful for segmenting DHCP services in multi-VLAN environments where some VLANs should use external DHCP servers while others use the router.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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.

Visual reference

Client DHCP Server 1 Discover (broadcast) 2 Offer (IP: 192.168.1.10) 3 Request (I accept) 4 Acknowledge (lease confirmed) DORA — the four-step DHCP lease process

What to study next

Got this wrong? Here's your next step.

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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) — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Configure 'no ip dhcp server' under the interface associated with the VLAN. — Option B is correct because configuring 'ip dhcp excluded-address' for the entire subnet of the VLAN prevents the router from offering any IP addresses in that subnet, effectively stopping it from acting as a DHCP server for that VLAN. Option E is correct because the global command 'no service dhcp' disables the DHCP server feature entirely on the router, which also prevents it from serving DHCP for the specific VLAN, albeit globally. Options A, C, and D are incorrect because they do not disable DHCP server functionality for the VLAN: A is not a valid command, C disables a security feature that does not affect the router's ability to serve DHCP, and D is used for relay agent trust, not server prevention.

What should I do if I get this 300-410 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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