Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Your company has an Azure subscription with a hub-spoke network topology. The hub contains an Azure Firewall and a VPN gateway for on-premises connectivity. The spoke virtual network hosts a critical application. You need to ensure that all outbound traffic from the spoke to the internet and on-premises networks flows through the Azure Firewall. You configure a user-defined route (UDR) on the spoke subnet with the default route (0.0.0.0/0) pointing to the Azure Firewall private IP. However, traffic to on-premises still bypasses the firewall. 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 on-premises traffic uses a more specific route learned via BGP from the VPN gateway, which overrides the UDR
BGP-learned routes for on-premises networks are more specific than 0.0.0.0/0. They will be used even if a UDR for 0.0.0.0/0 exists. To force through firewall, you must either disable BGP route propagation or create specific UDRs for on-premises ranges.
B
Distractor review
The UDR must be applied to the subnet that hosts the Azure Firewall
UDRs are applied to source subnets, not the firewall subnet. The spoke subnet UDR is correctly configured.
C
Distractor review
The spoke subnet does not have 'GatewaySubnet' route propagation enabled
Route propagation refers to learning BGP routes from a VPN gateway. If it were disabled, the spoke would not learn on-premises routes and would use the 0.0.0.0/0 UDR for all traffic. In this case, the problem is that propagation is enabled and the more specific routes override.
D
Distractor review
The Azure Firewall is not configured with a route to the on-premises network
The firewall needs a route to the on-premises network to forward traffic, but that does not explain why traffic bypasses the firewall from the spoke.
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.
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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 on-premises traffic uses a more specific route learned via BGP from the VPN gateway, which overrides the UDR — When VNet peering is configured to use the hub's VPN gateway, the spoke VNet learns more specific routes for on-premises prefixes via BGP. These BGP routes have a smaller prefix than 0.0.0.0/0, so they take precedence over the UDR, causing traffic to bypass the firewall.
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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