Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
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?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
Add a route table to VNet-B so traffic can bypass the overlap.
Route tables affect traffic flow after networking is established, but they do not resolve overlapping address spaces between VNets.
B
Best answer
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
Distractor review
Create a network security group rule to allow all traffic between the VNets.
NSG rules control allowed ports and protocols, but they do not fix overlapping CIDR ranges or enable peering creation.
D
Distractor review
Enable gateway transit on VNet-A so the address conflict is ignored.
Gateway transit supports routing through a VPN or ExpressRoute gateway, but it does not bypass the peering requirement for unique address spaces.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A route table contains these entries: 10.0.0.0/8 with next hop Virtual appliance, and 10.1.1.0/24 with next hop Virtual network gateway. Which next hop will Azure use for traffic to 10.1.1.5?
Question 2
You are deploying a stateless web application on Azure virtual machines. The solution must automatically add and remove instances based on CPU demand and allow all instances to be managed as one logical group. Which Azure compute feature should you deploy?
Question 3
You are deploying a Windows Server VM for an internal app. The VM must support Secure Boot and vTPM later, its OS disk must survive host moves, and the team wants the lowest-cost managed disk tier that still behaves like a normal writable OS disk. Which two choices should you make? Select two.
Question 4
You need to deploy several identical virtual machines and ensure that the failure of a single Azure host does not affect all of them. Which feature should you use?
Question 5
You need to connect VNet-Hub and VNet-Spoke so that resources in both virtual networks can communicate privately over the Microsoft backbone. Both virtual networks are in the same region. What should you configure?
Question 6
You need to create a storage account that provides the lowest-cost redundant storage for non-critical data and only needs protection against local disk or server failure within a single datacenter. Which redundancy option should you choose?
FAQ
Questions learners often ask
What does this AZ-104 question test?
CIDR notation defines the prefix length.
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 only works when each virtual network has a unique, non-overlapping address space. In this scenario, the two VNets both use parts of 10.20.0.0/16, so Azure rejects the peering request. The administrator must renumber one network before the relationship can be created. After the address ranges are fixed, traffic can flow over the Microsoft backbone using private IPs without adding extra routing components. Why others are wrong: A route table or NSG rule cannot repair overlapping IP space; those controls apply after connectivity exists. Gateway transit is meant for using a gateway across peerings, not for ignoring CIDR conflicts. The fundamental blocker here is the IP plan, so renumbering one VNet is the only valid first step.
What should I do if I get this AZ-104 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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