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
VNet-Prod address space: 10.40.0.0/16
VNet-Shared address space: 10.40.128.0/17
Operation result: Create peering failed
Error: Address space overlap detected between the selected virtual networks.
Based on the exhibit, an administrator is trying to peer two VNets so workloads can communicate privately. The peering creation fails. What should the administrator do first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
VNet-Prod address space: 10.40.0.0/16
VNet-Shared address space: 10.40.128.0/17
Operation result: Create peering failed
Error: Address space overlap detected between the selected virtual networks.
A
Create a user-defined route in VNet-Prod to force traffic through a firewall.
Why wrong: A route table does not resolve overlapping IP ranges between virtual networks. The peering operation fails before routing is even relevant.
B
Readdress one of the VNets so the address spaces no longer overlap.
Azure VNet peering requires non-overlapping address spaces. The correct first step is to change one VNet to a unique, non-conflicting prefix before attempting peering again. Once the overlap is removed, the peering can be created and traffic can flow privately between the networks.
C
Enable gateway transit on both VNets and retry the peering.
Why wrong: Gateway transit helps with on-premises connectivity through a gateway, but it does not solve overlapping CIDR ranges. The peering still cannot be created while address spaces conflict.
D
Add an NSG rule that allows traffic from the other VNet.
Why wrong: NSG rules control filtering after connectivity exists. They cannot overcome a hard peering requirement such as overlapping address spaces, so the peering failure remains.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Readdress one of the VNets so the address spaces no longer overlap.
VNet peering requires that the address spaces of the two virtual networks do not overlap. Overlapping address spaces cause routing conflicts and prevent the peering from being established. The administrator must readdress one of the VNets so their IP ranges are unique before retrying the peering.
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.
✗
Create a user-defined route in VNet-Prod to force traffic through a firewall.
Why it's wrong here
A route table does not resolve overlapping IP ranges between virtual networks. The peering operation fails before routing is even relevant.
✓
Readdress one of the VNets so the address spaces no longer overlap.
Why this is correct
Azure VNet peering requires non-overlapping address spaces. The correct first step is to change one VNet to a unique, non-conflicting prefix before attempting peering again. Once the overlap is removed, the peering can be created and traffic can flow privately between the networks.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable gateway transit on both VNets and retry the peering.
Why it's wrong here
Gateway transit helps with on-premises connectivity through a gateway, but it does not solve overlapping CIDR ranges. The peering still cannot be created while address spaces conflict.
✗
Add an NSG rule that allows traffic from the other VNet.
Why it's wrong here
NSG rules control filtering after connectivity exists. They cannot overcome a hard peering requirement such as overlapping address spaces, so the peering failure remains.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on network security or traffic control (NSGs, UDRs, gateway transit) instead of recognizing that VNet peering has a strict prerequisite of non-overlapping address spaces, which is a common misconfiguration in real-world scenarios.
Detailed technical explanation
How to think about this question
Azure VNet peering relies on the Azure backbone to route traffic between VNets using the system routes. If address spaces overlap, the Azure platform cannot uniquely determine which VNet a packet belongs to, leading to ambiguous routing and peering failure. This is enforced at the control plane during peering creation, and the error message typically indicates 'Address space overlap' or 'Cannot peer virtual networks with overlapping address spaces'.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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: Readdress one of the VNets so the address spaces no longer overlap. — VNet peering requires that the address spaces of the two virtual networks do not overlap. Overlapping address spaces cause routing conflicts and prevent the peering from being established. The administrator must readdress one of the VNets so their IP ranges are unique before retrying the peering.
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.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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