CCNA Network Services and Security Practice Question
A network administrator is troubleshooting a switch that is receiving DHCPDISCOVER messages from a client on VLAN 20, but the DHCP server on a different subnet never sees those requests. The interface VLAN 20 has the address 10.20.0.1/24, and the DHCP server address is 10.99.0.10. Which command should be applied to enable the switch to forward these requests to the server?
⚠ Common exam trap
The trap here is assuming that enabling option 82 or listing UDP port 67 is enough, when only the ip helper-address statement actually forwards the client request to the server.
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
✓
ip helper-address 10.99.0.10
DHCP relay is configured with the ip helper-address command on the interface facing the clients, which unicasts their DHCP broadcasts to the specified server and sets the gateway address so the server can match the correct scope. Without it, the broadcast stays on the local subnet and the remote server never receives the request.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ip dhcp pool VLAN20
Why it's wrong here
The ip dhcp pool command creates a DHCP server address pool on the local device, which is the opposite of relay behavior. The scenario already has an external DHCP server at 10.99.0.10, so configuring a local pool would either conflict with that server or assign addresses from the wrong source.
- ✗
ip forward-protocol udp 67
Why it's wrong here
The ip forward-protocol command controls which UDP ports the router relays when helper addresses are already configured, but it does not create the relay destination itself. Without an ip helper-address specifying the server, no UDP broadcast is forwarded regardless of which ports are enabled for forwarding.
- ✗
ip dhcp relay information option
Why it's wrong here
This command enables insertion of the DHCP relay agent information option, sometimes called option 82, which carries port and VLAN details for the server. It does not itself forward the broadcast to a server, so without an ip helper-address statement the DHCPDISCOVER messages still never leave the local subnet.
- ✓
ip helper-address 10.99.0.10
Why this is correct
The ip helper-address command on the client VLAN's SVI converts broadcast DHCPDISCOVER messages into unicast packets destined for the specified server address. It also fills in the gateway address field so the server can select the correct scope for the 10.20.0.0/24 subnet, allowing the reply to be routed back to the client.
Visual reference
Go deeper
Related to this question
Learn chapter
DHCP Process
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
About these practice questions
Courseiva writes every 200-301 question from scratch — 1,450 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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.