- A
Add a route table to VNet-B so traffic can bypass the overlap.
Why wrong: Route tables affect traffic flow after networking is established, but they do not resolve overlapping address spaces between VNets.
- B
Change VNet-B to a non-overlapping address space before creating the peering.
Azure VNet peering requires that the peered VNets use non-overlapping IP address ranges. Because VNet-B overlaps with VNet-A, the peering cannot be created successfully until one side is renumbered. The safest first step is to plan and apply a new, unique CIDR block for VNet-B that does not conflict with any existing subnet or on-premises range. Once the address spaces are non-overlapping, peering can be created and private connectivity can work as intended.
- C
Create a network security group rule to allow all traffic between the VNets.
Why wrong: NSG rules control allowed ports and protocols, but they do not fix overlapping CIDR ranges or enable peering creation.
- D
Enable gateway transit on VNet-A so the address conflict is ignored.
Why wrong: Gateway transit supports routing through a VPN or ExpressRoute gateway, but it does not bypass the peering requirement for unique address spaces.
Quick Answer
The correct first step is to change VNet-B’s address space to a non-overlapping range before creating the peering. This is required because Azure VNet peering mandates that the address spaces of peered virtual networks must not overlap; VNet-A uses 10.20.0.0/16 and VNet-B uses 10.20.1.0/24, which is a direct subset of VNet-A’s range, causing the peering operation to fail due to conflicting routes. On the AZ-104 exam, this scenario tests your understanding of VNet peering prerequisites and the fact that overlapping address spaces are a common misconfiguration that blocks connectivity—even if subnets are already deployed, you must resolve the overlap first. A frequent trap is assuming you can use network address translation or gateway transit to work around the conflict, but Azure requires non-overlapping ranges for direct peering. Memory tip: “Peers need separate streets—no overlapping ZIP codes.”
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.
An administrator plans to peer VNet-A with VNet-B so two application tiers can communicate over private IPs. VNet-A uses 10.20.0.0/16. VNet-B currently uses 10.20.1.0/24, and both VNets already contain subnets that must remain intact. The peering operation 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.
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
Change VNet-B to a non-overlapping address space before creating the peering.
VNet peering in Azure requires that the address spaces of the peered VNets do not overlap. VNet-A uses 10.20.0.0/16 and VNet-B uses 10.20.1.0/24, which is a subset of VNet-A's range, creating a direct overlap. The peering operation fails because Azure cannot route traffic correctly when address spaces conflict. The first step must be to change VNet-B's address space to a non-overlapping range (e.g., 10.21.0.0/16) before attempting to create 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.
- ✗
Add a route table to VNet-B so traffic can bypass the overlap.
Why it's wrong here
Route tables affect traffic flow after networking is established, but they do not resolve overlapping address spaces between VNets.
- ✓
Change VNet-B to a non-overlapping address space before creating the peering.
Why this is correct
Azure VNet peering requires that the peered VNets use non-overlapping IP address ranges. Because VNet-B overlaps with VNet-A, the peering cannot be created successfully until one side is renumbered. The safest first step is to plan and apply a new, unique CIDR block for VNet-B that does not conflict with any existing subnet or on-premises range. Once the address spaces are non-overlapping, peering can be created and private connectivity can work as intended.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a network security group rule to allow all traffic between the VNets.
Why it's wrong here
NSG rules control allowed ports and protocols, but they do not fix overlapping CIDR ranges or enable peering creation.
- ✗
Enable gateway transit on VNet-A so the address conflict is ignored.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think they can use route tables or NSG rules to work around the overlap, but Azure enforces non-overlapping address spaces at the peering creation stage, making any post-creation workaround impossible.
Detailed technical explanation
How to think about this question
Azure VNet peering uses the backbone network to route traffic between VNets, relying on the Azure Route Server to match destination IPs to the peered VNet's address space. When address spaces overlap, the route table becomes ambiguous, and Azure's control plane rejects the peering request with an error like 'Address space overlaps with existing peered VNet.' The only way to resolve this is to modify the overlapping VNet's address space, which may require deleting subnets and recreating them in the new range, or using a different VNet entirely.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this AZ-104 question test?
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: Change VNet-B to a non-overlapping address space before creating the peering. — VNet peering in Azure requires that the address spaces of the peered VNets do not overlap. VNet-A uses 10.20.0.0/16 and VNet-B uses 10.20.1.0/24, which is a subset of VNet-A's range, creating a direct overlap. The peering operation fails because Azure cannot route traffic correctly when address spaces conflict. The first step must be to change VNet-B's address space to a non-overlapping range (e.g., 10.21.0.0/16) before attempting to create 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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Last reviewed: Jun 11, 2026
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.
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