AZ-104 Implement and Manage Virtual Networking Practice Question
A network team centralizes DHCP in a data center. Users in a remote branch stop receiving addresses after the branch router is replaced. Which missing configuration on the branch gateway is the strongest suspect?
⚠ Common exam trap
Many exam-takers confuse DHCP relay with other broadcast-forwarding mechanisms or assume that DHCP works automatically across routers, forgetting that routers by default do not forward broadcasts unless explicitly configured with ip helper-address.
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
✓
DHCP relay or helper configuration on the client-facing gateway interface
When a DHCP server is centralized in a data center, remote clients rely on the branch gateway to forward their broadcast DHCP requests as unicast to the server. This is achieved by configuring a DHCP relay agent (ip helper-address) on the client-facing interface of the branch router. Without this configuration, DHCP broadcasts are dropped at the router, and clients never receive IP addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DHCP relay or helper configuration on the client-facing gateway interface
Why this is correct
Configuring DHCP relay (ip helper-address) on the client-facing gateway interface is essential because DHCP discovery packets are Layer 2 broadcasts that will not cross a Layer 3 boundary. The relay agent converts those broadcasts into unicast messages and forwards them to the centralized DHCP server, while inserting its own interface IP into the giaddr field so the server can assign an address from the correct subnet pool. Without this helper/relay setting, clients remain isolated from the data center DHCP server.
- ✗
A spanning-tree priority change on the branch switch
Why it's wrong here
Changing the spanning-tree priority on an access or distribution switch determines which switch becomes the root bridge in the Layer 2 topology, thereby influencing the path for frames within a broadcast domain. However, STP exists solely to prevent bridging loops; it does not forward or filter broadcasts across VLANs or subnets, and it does not relay DHCP frames to a remote server. The root bridge selection has zero impact on DHCP operations at the client-facing gateway.
When this WOULD be correct
In a different scenario, if the question involved a network outage or connectivity issues due to a misconfigured spanning-tree protocol, a change in spanning-tree priority could be the cause of devices not receiving network services, including DHCP. This would make option B the correct answer.
- ✗
A CAPWAP tunnel from the branch PCs to the data center
Why it's wrong here
CAPWAP tunnels are used in wireless LAN architectures to transport traffic between lightweight access points and a wireless controller, typically for centralized forwarding of WLAN data and control frames. Branch PCs that are wired clients do not use CAPWAP; only wireless clients tunnel through CAPWAP, and even then it does not relay DHCP discovery broadcasts between a wired network and a central DHCP server. CAPWAP is unrelated to IP helper or DHCP relay on a layer 3 gateway.
When this WOULD be correct
In a scenario where the question involves a wireless network setup with lightweight access points that rely on a CAPWAP tunnel for communication with a controller, a misconfigured CAPWAP tunnel could prevent devices from obtaining necessary network configurations, including DHCP addresses.
- ✗
A voice VLAN configuration on the WAN interface
Why it's wrong here
Voice VLAN configuration on a WAN interface is applicable only to Layer 2 access ports that connect IP phones and PCs, where 802.1Q tagging separates voice traffic from data traffic. A WAN interface is a routed or trunking interface carrying inter-site traffic, and it does not host client devices, so configuring a voice VLAN there would have no effect on DHCP broadcast forwarding. DHCP relay is handled by the gateway's L3 forwarding, not by VLAN tags.
When this WOULD be correct
In a different scenario where the question involves configuring QoS for voice traffic over a WAN link, a question might ask about ensuring proper VLAN configurations for voice traffic, making option D the correct choice.
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 AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓DHCP relay or helper configuration on the client-facing gateway interfaceCorrect answer▾
Why this is correct
Configuring DHCP relay (ip helper-address) on the client-facing gateway interface is essential because DHCP discovery packets are Layer 2 broadcasts that will not cross a Layer 3 boundary. The relay agent converts those broadcasts into unicast messages and forwards them to the centralized DHCP server, while inserting its own interface IP into the giaddr field so the server can assign an address from the correct subnet pool. Without this helper/relay setting, clients remain isolated from the data center DHCP server.
✗A spanning-tree priority change on the branch switchWrong answer — click to see why▾
Why this is wrong here
A spanning-tree priority change on the branch switch does not directly affect DHCP address allocation; it primarily influences the topology and path selection of the network. Since the issue is related to DHCP address assignment, this option is not relevant.
★ When this WOULD be the correct answer
In a different scenario, if the question involved a network outage or connectivity issues due to a misconfigured spanning-tree protocol, a change in spanning-tree priority could be the cause of devices not receiving network services, including DHCP. This would make option B the correct answer.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of how network topology changes can impact service delivery, leading them to incorrectly associate spanning-tree adjustments with DHCP functionality.
✗A CAPWAP tunnel from the branch PCs to the data centerWrong answer — click to see why▾
Why this is wrong here
A CAPWAP tunnel is used for managing lightweight access points and does not directly relate to DHCP address assignment. Since the issue is with users not receiving DHCP addresses, a CAPWAP tunnel would not be the cause of the problem.
★ When this WOULD be the correct answer
In a scenario where the question involves a wireless network setup with lightweight access points that rely on a CAPWAP tunnel for communication with a controller, a misconfigured CAPWAP tunnel could prevent devices from obtaining necessary network configurations, including DHCP addresses.
Why candidates choose this
Candidates may confuse the role of CAPWAP in managing network devices and assume that any network connectivity issue could be related to CAPWAP configurations, leading them to select this option without fully understanding the specific DHCP context.
✗A voice VLAN configuration on the WAN interfaceWrong answer — click to see why▾
Why this is wrong here
A voice VLAN configuration on the WAN interface is unrelated to DHCP address assignment issues, as voice VLANs are used for prioritizing voice traffic rather than facilitating DHCP communication.
★ When this WOULD be the correct answer
In a different scenario where the question involves configuring QoS for voice traffic over a WAN link, a question might ask about ensuring proper VLAN configurations for voice traffic, making option D the correct choice.
Why candidates choose this
Candidates may choose this option due to a misunderstanding of VLAN configurations, thinking that any misconfiguration on the WAN interface could affect overall network services, including DHCP.
Analysis generated from the official AZ-104blueprint 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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Key term
DHCP
Dynamic Host Configuration Protocol (DHCP) automatically assigns IP addresses and network settings to devices on a network, so they can communicate without manual configuration.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-104 practice question is part of Courseiva's free Microsoft 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 AZ-104 exam.