The best fix is to change one VNet to a non-overlapping address range, then create the peering again. This is required because Azure VNet peering mandates that the address spaces of peered virtual networks must not overlap; overlapping ranges create routing conflicts where Azure cannot determine which VNet should handle traffic for the shared IP block. In this scenario, VNet-A’s 10.4.0.0/16 fully contains VNet-B’s 10.4.128.0/17, so the peering is rejected. On the AZ-104 exam, this tests your understanding of VNet peering prerequisites and CIDR subnetting—a common trap is assuming you can use overlapping ranges if they are in different subscriptions, but Azure enforces non-overlap globally. A quick memory tip: “Peering needs no overlap—if one range swallows the other, change the smaller or the larger.”
AZ-104 Implement and Manage Virtual Networking Practice Question
This AZ-104 practice question tests your understanding of implement and manage virtual networking. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Two virtual networks were created in different subscriptions. VNet-A uses 10.4.0.0/16 and VNet-B uses 10.4.128.0/17. You try to create peering between them, but Azure rejects the request. What is the best fix?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change one VNet to a non-overlapping address range, then create the peering again.
VNet peering requires that the address spaces of the two virtual networks do not overlap. VNet-A uses 10.4.0.0/16, which covers 10.4.0.0 to 10.4.255.255, and VNet-B uses 10.4.128.0/17, which falls entirely within that range (10.4.128.0 to 10.4.255.255). Azure rejects the peering because overlapping address spaces would cause routing conflicts. The only correct fix is to change one VNet's address space to a non-overlapping range, then recreate 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.
✗
Enable gateway transit on both VNets before creating the peering.
Why it's wrong here
Gateway transit does not solve overlapping address space conflicts during peering creation.
✗
Add a route table to one VNet so the address spaces no longer overlap.
Why it's wrong here
Route tables do not change IP address assignment, so the overlap still exists.
✓
Change one VNet to a non-overlapping address range, then create the peering again.
Why this is correct
Azure virtual network peering requires non-overlapping address spaces, so renumbering is the correct fix.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a private endpoint between the two VNets instead of peering.
Why it's wrong here
Private endpoints connect to supported services, not as a replacement for VNet-to-VNet peering.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think adding a route table or enabling gateway transit can fix the overlap, but Azure enforces a strict non-overlapping address space requirement for VNet peering at the time of creation, and no routing configuration can bypass this fundamental constraint.
Detailed technical explanation
How to think about this question
VNet peering uses the Azure backbone to route traffic between VNets, relying on the address spaces to build implicit routes in each VNet's routing table. When address spaces overlap, Azure cannot create these routes without ambiguity, leading to a conflict that prevents peering from being established. In a real-world scenario, overlapping address spaces often occur when merging networks from different organizations or during IP address planning errors, requiring re-IPing of one VNet to a non-conflicting CIDR block, such as changing 10.4.128.0/17 to 10.5.0.0/16.
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 one VNet to a non-overlapping address range, then create the peering again. — VNet peering requires that the address spaces of the two virtual networks do not overlap. VNet-A uses 10.4.0.0/16, which covers 10.4.0.0 to 10.4.255.255, and VNet-B uses 10.4.128.0/17, which falls entirely within that range (10.4.128.0 to 10.4.255.255). Azure rejects the peering because overlapping address spaces would cause routing conflicts. The only correct fix is to change one VNet's address space to a non-overlapping range, then recreate 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: "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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