300-410 Infrastructure Services Practice Question
A network technician is configuring a Cisco router to act as a DHCP relay agent. The router's interface Gi0/0 is connected to the DHCP clients, and the DHCP server is reachable via interface Gi0/1. Which command must be configured on interface Gi0/0 to forward DHCP requests to the server at 192.168.1.10?
⚠ Common exam trap
The trap here is thinking that a dedicated DHCP relay command exists, such as 'ip dhcp relay', when in fact Cisco IOS uses the generic 'ip helper-address' to forward DHCP and other UDP broadcasts.
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 192.168.1.10
To configure a Cisco router as a DHCP relay agent, the 'ip helper-address' command is applied on the interface receiving DHCP broadcasts. It forwards these broadcasts as unicasts to the specified DHCP server. This allows clients on one subnet to obtain IP addresses from a server on another subnet. Other commands like 'ip forward-protocol' are supplementary and do not specify the server.
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 forward-protocol udp 192.168.1.10
Why it's wrong here
'ip forward-protocol udp' is used to specify which UDP ports are forwarded when a helper address is configured. It does not specify the server IP address. The command alone does not enable DHCP relay; it only defines the protocols. The server address is specified with 'ip helper-address'.
- ✗
ip dhcp relay 192.168.1.10
Why it's wrong here
'ip dhcp relay' is not a valid Cisco IOS command. The correct command to configure a DHCP relay agent is 'ip helper-address'. This distractor might confuse those who think there is a dedicated DHCP relay command, but Cisco uses the helper-address mechanism for UDP broadcast forwarding.
- ✓
ip helper-address 192.168.1.10
Why this is correct
The 'ip helper-address' command is used on the interface facing the DHCP clients to forward broadcast DHCP requests to a specific DHCP server. It converts the broadcast to a unicast packet destined for the server. This is the correct command to enable DHCP relay functionality on the client-facing interface.
- ✗
ip dhcp-server 192.168.1.10
Why it's wrong here
'ip dhcp-server' is not a valid command for configuring a DHCP relay agent. It might be confused with DHCP server configuration commands like 'ip dhcp pool' or 'service dhcp'. The correct command to forward DHCP requests to a remote server is 'ip helper-address' on the client-facing interface.
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Key term
DHCP Client and Server
A DHCP client is any device that requests network configuration settings from a DHCP server, which automatically assigns IP addresses and other parameters to devices on a network.
Key term
DHCP Relay Configuration
A DHCP relay configuration allows a router to forward DHCP broadcast requests from clients on one subnet to a DHCP server on a different subnet, enabling centralized IP address management across multiple networks.
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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 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.