CCNA Network Services and Security Practice Question
A network technician is troubleshooting a DHCP relay issue. The router at the branch office is supposed to forward DHCP requests from local clients to a central DHCP server. Clients connected to Gi0/1 are not receiving IP addresses. The technician verifies that the DHCP server is reachable from the router, that no ACLs are blocking DHCP traffic, and that the DHCP scope on the server has available leases. Upon checking the running configuration, the technician notices that the ip helper-address command is applied to interface Gi0/0 (the WAN link toward the server) instead of Gi0/1. What should the technician do next?
⚠ Common exam trap
Cisco often tests the misconception that the ip helper-address should be placed on the interface closest to the server (outbound), when in fact it must be on the interface that receives the client broadcast (inbound).
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
✓
Move the ip helper-address command from interface Gi0/0 to interface Gi0/1.
The ip helper-address command must be applied to the interface that receives the DHCP broadcast from clients, which is Gi0/1 in this scenario. It converts the broadcast into a unicast directed to the DHCP server. Applying it to Gi0/0 (the WAN interface) is ineffective because broadcasts are not forwarded across routers by default, and the helper address must be on the ingress interface of the client subnet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Check the DHCP server logs for any error or warning messages related to the clients' requests.
Why it's wrong here
The server logs will not show any incoming DHCP discovers from these clients because the router is not forwarding them from the correct interface. Investigating server logs would be a waste of time when the configuration error is already visible.
- ✓
Move the ip helper-address command from interface Gi0/0 to interface Gi0/1.
Why this is correct
DHCP relay requires the helper address to be configured on the interface that faces the DHCP clients (the broadcast domain where clients send their DHCPDISCOVER messages). By moving the command to Gi0/1, the router will correctly intercept and forward client requests to the DHCP server.
- ✗
Issue the show ip interface brief command to ensure that interface Gi0/1 is in an up/up state.
Why it's wrong here
Checking interface status is a basic step, but the technician would have noticed if the interface were down from the start. Moreover, the router's running config was already examined, so the interface must be at least administratively up for the technician to have been troubleshooting client connectivity. The core issue is the helper-address placement, not the interface state.
- ✗
Remove the ip helper-address from Gi0/0 and then reapply it to the same interface to ensure the command is active.
Why it's wrong here
Reapplying the command to the wrong interface does not change the behavior; the router will still not see client DHCP broadcasts on the WAN link. The helper address must be on the interface that receives the broadcasts.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Move the ip helper-address command from interface Gi0/0 to interface Gi0/1.Correct answer▾
Why this is correct
DHCP relay requires the helper address to be configured on the interface that faces the DHCP clients (the broadcast domain where clients send their DHCPDISCOVER messages). By moving the command to Gi0/1, the router will correctly intercept and forward client requests to the DHCP server.
✗Check the DHCP server logs for any error or warning messages related to the clients' requests.Wrong answer — click to see why▾
Why this is wrong here
This skips the obvious configuration mismatch and targets the wrong component. It assumes the issue is on the server side rather than the router's DHCP relay placement.
✗Issue the show ip interface brief command to ensure that interface Gi0/1 is in an up/up state.Wrong answer — click to see why▾
Why this is wrong here
This action investigates Layer 1/2 status when the problem is already identified as a Layer 3 (DHCP relay) configuration error. It skips applying the fix and delays resolution.
✗Remove the ip helper-address from Gi0/0 and then reapply it to the same interface to ensure the command is active.Wrong answer — click to see why▾
Why this is wrong here
Candidates might think the command simply didn't take effect and that reapplying it solves the problem, misunderstanding the directional requirement of DHCP relay placement.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Related to this question
Learn chapter
Diagnosing DNS Record Issues — A, AAAA, CNAME, MX, NS, and PTR Records
Key term
DHCP server
A DHCP server is a network device or service that automatically assigns IP addresses and other network configuration parameters to devices on a network, eliminating the need for manual configuration.
Key term
WAN
A Wide Area Network (WAN) is a telecommunications network that connects multiple smaller networks, like local area networks, across large geographical distances.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.