The answer is to change VNet-B to a non-overlapping address space, such as 10.1.0.0/24. This is correct because VNet peering requires that the address spaces of the two virtual networks do not overlap; Azure cannot route traffic between networks that share the same IP range, as it would create ambiguity for packet forwarding. On the AZ-104 exam, this scenario tests your understanding of fundamental VNet peering constraints, often presented in an exhibit where two VNets use identical CIDR blocks like 10.0.0.0/16, and the trap is assuming you can simply enable peering without addressing the conflict. A common memory tip is to think of VNet peering as a direct bridge—you cannot have two houses with the same street address on the same bridge. Remember the rule: no overlapping address spaces, or the peering fails.
AZ-104 Implement and Manage Virtual Networking Practice Question
This AZ-104 practice question tests your understanding of implement and manage virtual networking. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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-A address space: 10.0.0.0/16
VNet-B address space: 10.0.1.0/24
Attempt to peer VNet-A and VNet-B:
Status: Failed
Error: Address space overlap detected
Requirement: Both VNets must remain connected, but the address spaces must not overlap.
Based on the exhibit, what is the best change so the VNet peering can be created successfully?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
VNet-A address space: 10.0.0.0/16
VNet-B address space: 10.0.1.0/24
Attempt to peer VNet-A and VNet-B:
Status: Failed
Error: Address space overlap detected
Requirement: Both VNets must remain connected, but the address spaces must not overlap.
A
Change VNet-B to a non-overlapping address space, such as 10.1.0.0/24.
Azure VNet peering requires that the address spaces do not overlap. Changing VNet-B to a different range removes the conflict and allows peering to be created. The exact new range can vary, but it must not overlap with VNet-A’s 10.0.0.0/16 range.
B
Add a route table to VNet-B before creating the peering.
Why wrong: Route tables do not resolve overlapping address spaces. The peering fails before any routing behavior matters.
C
Enable gateway transit on VNet-A.
Why wrong: Gateway transit is used to share a VPN or ExpressRoute gateway through peering. It does not fix overlapping CIDR blocks.
D
Resize VNet-A to 10.0.0.0/15 so both VNets fit.
Why wrong: Making the larger range would actually expand overlap instead of removing it. Peering still cannot be established when address spaces overlap.
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, such as 10.1.0.0/24.
VNet peering requires that the address spaces of the two virtual networks do not overlap. If VNet-A uses 10.0.0.0/16 and VNet-B also uses 10.0.0.0/16, they conflict, preventing peering. Changing VNet-B to a non-overlapping address space like 10.1.0.0/24 resolves this conflict, allowing the peering to be established.
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.
✓
Change VNet-B to a non-overlapping address space, such as 10.1.0.0/24.
Why this is correct
Azure VNet peering requires that the address spaces do not overlap. Changing VNet-B to a different range removes the conflict and allows peering to be created. The exact new range can vary, but it must not overlap with VNet-A’s 10.0.0.0/16 range.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add a route table to VNet-B before creating the peering.
Why it's wrong here
Route tables do not resolve overlapping address spaces. The peering fails before any routing behavior matters.
✗
Enable gateway transit on VNet-A.
Why it's wrong here
Gateway transit is used to share a VPN or ExpressRoute gateway through peering. It does not fix overlapping CIDR blocks.
✗
Resize VNet-A to 10.0.0.0/15 so both VNets fit.
Why it's wrong here
Making the larger range would actually expand overlap instead of removing it. Peering still cannot be established when address spaces overlap.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse overlapping address spaces with routing issues, thinking that adding route tables or enabling gateway transit will fix the peering failure, when in fact the fundamental requirement is non-overlapping IP ranges.
Detailed technical explanation
How to think about this question
Azure VNet peering uses a hub-and-spoke or mesh topology where each VNet must have a unique, non-overlapping CIDR block. The peering connection is established at the Azure Resource Manager level, and the address spaces are validated during creation; if they overlap, the API returns a conflict error. In real-world scenarios, overlapping address spaces often occur when merging networks from different organizations or during migration, requiring careful IP address planning or use of NAT solutions.
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: Change VNet-B to a non-overlapping address space, such as 10.1.0.0/24. — VNet peering requires that the address spaces of the two virtual networks do not overlap. If VNet-A uses 10.0.0.0/16 and VNet-B also uses 10.0.0.0/16, they conflict, preventing peering. Changing VNet-B to a non-overlapping address space like 10.1.0.0/24 resolves this conflict, allowing the peering to be established.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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