Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company has two Azure virtual networks, VNet-A (hub) and VNet-B (spoke), connected via VNet peering. They deployed a network virtual appliance (NVA) in a subnet in VNet-A to inspect all traffic. They configured a user-defined route (UDR) on the subnet in VNet-B that points the VNet-A address space (10.0.0.0/16) to the private IP of the NVA. However, traffic initiated from VNet-B to VNet-A still takes a direct path and bypasses the NVA. What is the most likely cause?
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
Best answer
The NVA does not have IP forwarding enabled on its network interface
When an NVA is used as a next hop in a route table, it must have IP forwarding enabled. Without it, the NVA drops packets that are not destined for its own IP, effectively preventing traffic from being routed through it.
B
Distractor review
The UDR on VNet-B must also include a route for the default route (0.0.0.0/0) to force all traffic through the NVA
The scenario only concerns traffic between VNet-B and VNet-A. A default route is not required to force traffic between the two VNets through the NVA; the specific route for the VNet-A address space should be sufficient.
C
Distractor review
VNet peering does not support user-defined routes
VNet peering supports user-defined routes. You can apply UDRs to subnets in one VNet to control traffic to the peered VNet.
D
Distractor review
The NVA must be deployed in the same subnet as the source VMs in VNet-B
The NVA can be in a different VNet as long as routing is correctly configured. The issue is not about the NVA's location but about forwarding capabilities.
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.
Related practice questions
Related AZ-500 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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.
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FAQ
Questions learners often ask
What does this AZ-500 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: The NVA does not have IP forwarding enabled on its network interface — When using an NVA to inspect traffic between peered VNets, you need to ensure that both the source and return traffic go through the NVA. A common mistake is forgetting to configure IP forwarding on the NVA's network interface. Without IP forwarding, when the NVA receives a packet destined for an address other than itself, it drops the packet. The UDR on the spoke subnet directs traffic to the NVA's IP, but the NVA cannot forward that traffic unless IP forwarding is enabled on its NIC. Additionally, return traffic from the hub subnet needs another UDR pointing to the NVA for the spoke address space. The most likely single cause in this scenario is the lack of IP forwarding on the NVA.
What should I do if I get this AZ-500 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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