The answer is to configure the spoke VNet to use 10.20.0.4 as a custom DNS server for hostname resolution across peered VNets. This is correct because Azure-provided DNS cannot resolve custom private DNS zones or internal hostnames like app01.corp.local; it only handles public name resolution and Azure-assigned IPs. By pointing the spoke VNet’s DNS settings to the hub’s custom DNS server at 10.20.0.4—typically a Windows Server running the DNS role—the spoke VMs forward queries to the hub, enabling seamless internal name resolution across the peering. On the AZ-104 exam, this scenario tests your understanding of how custom DNS servers bridge name resolution gaps in hub-and-spoke topologies, a common trap being that VNet peering alone does not propagate DNS settings. Remember the memory tip: “Peering connects the roads, but custom DNS gives them names.”
AZ-104 Implement and Manage Virtual Networking Practice Question
This AZ-104 practice question tests your understanding of implement and manage virtual networking. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Hub VNet DNS server: 10.20.0.4
Spoke VNet DNS server setting: Azure-provided
Test from spoke VM:
ping 10.20.0.4 Success
nslookup app01.corp.local Server failed to find app01.corp.local: NXDOMAIN
Hub and spoke are already peered.
Based on the exhibit, VM name resolution works for IP addresses but fails for internal hostnames. What should the administrator configure on the spoke VNet?
Hub VNet DNS server: 10.20.0.4
Spoke VNet DNS server setting: Azure-provided
Test from spoke VM:
ping 10.20.0.4 Success
nslookup app01.corp.local Server failed to find app01.corp.local: NXDOMAIN
Hub and spoke are already peered.
A
Keep Azure-provided DNS because the spoke can already reach the hub by IP.
Why wrong: Connectivity by IP does not mean name resolution is configured correctly. Azure-provided DNS cannot resolve the custom internal domain shown in the exhibit.
B
Configure the spoke VNet to use 10.20.0.4 as a custom DNS server.
The exhibit shows the hub has a custom DNS server at 10.20.0.4, but the spoke is still using Azure-provided DNS. To resolve internal names such as app01.corp.local, the spoke VNet must point to the custom DNS server that knows that zone. After that change, VMs in the spoke can use the hub DNS service for name resolution.
C
Create a private endpoint for app01.corp.local in the spoke VNet.
Why wrong: A private endpoint is used for specific Azure PaaS services, not for general internal DNS hostnames or custom corporate zones. The issue in the exhibit is DNS configuration, not private service access.
D
Enable a NAT gateway on the spoke subnet.
Why wrong: A NAT gateway changes outbound internet source addresses. It does not provide hostname resolution or influence DNS lookups for internal names.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the spoke VNet to use 10.20.0.4 as a custom DNS server.
The hub VNet uses a custom DNS server at 10.20.0.4 (likely a Windows Server with DNS role) that can resolve internal hostnames like app01.corp.local. The spoke VNet is currently using Azure-provided DNS, which cannot resolve custom private DNS zones. By configuring the spoke VNet to use 10.20.0.4 as a custom DNS server, the spoke VMs will forward DNS queries to the hub DNS server, enabling hostname resolution for internal resources.
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.
✗
Keep Azure-provided DNS because the spoke can already reach the hub by IP.
Why it's wrong here
Connectivity by IP does not mean name resolution is configured correctly. Azure-provided DNS cannot resolve the custom internal domain shown in the exhibit.
✓
Configure the spoke VNet to use 10.20.0.4 as a custom DNS server.
Why this is correct
The exhibit shows the hub has a custom DNS server at 10.20.0.4, but the spoke is still using Azure-provided DNS. To resolve internal names such as app01.corp.local, the spoke VNet must point to the custom DNS server that knows that zone. After that change, VMs in the spoke can use the hub DNS service for name resolution.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a private endpoint for app01.corp.local in the spoke VNet.
Why it's wrong here
A private endpoint is used for specific Azure PaaS services, not for general internal DNS hostnames or custom corporate zones. The issue in the exhibit is DNS configuration, not private service access.
✗
Enable a NAT gateway on the spoke subnet.
Why it's wrong here
A NATgateway changes outbound internet source addresses. It does not provide hostname resolution or influence DNS lookups for internal names.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Azure-provided DNS can resolve custom hostnames across peered VNets, but it only resolves names within the same VNet unless a custom DNS server or Azure Private DNS Zone is configured.
Trap categories for this question
Command / output trap
Connectivity by IP does not mean name resolution is configured correctly. Azure-provided DNS cannot resolve the custom internal domain shown in the exhibit.
Detailed technical explanation
How to think about this question
When a VNet is configured with a custom DNS server, Azure DHCP assigns that server's IP to VMs, and all DNS queries are forwarded to it. The hub DNS server (10.20.0.4) must have conditional forwarders or be authoritative for the corp.local zone to resolve hostnames across peered VNets. This setup is common in hub-and-spoke topologies where centralized DNS is required for name resolution across multiple VNets.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-104 question in full detail.
Implement and Manage Virtual Networking — This question tests Implement and Manage Virtual Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure the spoke VNet to use 10.20.0.4 as a custom DNS server. — The hub VNet uses a custom DNS server at 10.20.0.4 (likely a Windows Server with DNS role) that can resolve internal hostnames like app01.corp.local. The spoke VNet is currently using Azure-provided DNS, which cannot resolve custom private DNS zones. By configuring the spoke VNet to use 10.20.0.4 as a custom DNS server, the spoke VMs will forward DNS queries to the hub DNS server, enabling hostname resolution for internal resources.
What should I do if I get this AZ-104 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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