- A
The Azure Firewall subnet is missing a route table entry for the 0.0.0.0/0 route
Why wrong: The firewall subnet itself does not need a default route for spoke traffic; it needs the correct routing to send inspected traffic out. This is not the most likely cause of spoke traffic bypassing.
- B
The route table on the spoke subnet has 'Propagate gateway routes' enabled, causing a conflicting route from the hub's VPN gateway
When gateway propagation is enabled, any routes from the hub's VPN/ExpressRoute gateway are automatically added. These routes can override the custom 0.0.0.0/0 route, especially if the hub has a default route learned via VPN. Disabling propagation resolves the conflict.
- C
The VNet peering does not allow forwarded traffic from the spoke to the firewall
Why wrong: Forwarded traffic is allowed by default when virtual network gateway is not used. The requirement for allowing forwarded traffic is the 'Allow virtual network gateway transit' setting in the hub and 'Use remote virtual network gateways' in the spoke, but this is for gateway transit, not for routing through a firewall instance.
- D
The Azure Firewall is not configured with the 'Allow outbound traffic' rule
Why wrong: Firewall rules affect which traffic is allowed, not the routing path. Even without a rule, traffic would still reach the firewall (if routed), but be dropped. The issue is that traffic never reaches the firewall.
Quick Answer
The answer is that the route table on the spoke subnet has 'Propagate gateway routes' enabled, which introduces a conflicting system route. When this setting is active, VNet peering with a hub that contains a VPN or ExpressRoute gateway injects a system default route (0.0.0.0/0) with a next hop of the virtual gateway. This system route has a lower route preference (higher priority) than your user-defined route (UDR) pointing to the Azure Firewall’s private IP, so traffic bypasses the firewall and flows directly to the gateway instead. On the AZ-500 exam, this scenario tests your understanding of Azure route selection and the interaction between forced tunneling UDR and propagate gateway routes. A common trap is assuming a UDR always overrides system routes, but gateway-propagated routes take precedence for the 0.0.0.0/0 prefix. Memory tip: “Propagate wins the default race” — if gateway routes propagate, your firewall UDR will lose the race for outbound traffic.
AZ-500 Secure networking Practice Question
This AZ-500 practice question tests your understanding of secure networking. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A company has an Azure virtual network (VNet) with multiple subnets. They deploy Azure Firewall in a hub VNet and peer spoke VNets. They want to force-tunnel all outbound traffic from a specific spoke subnet to the firewall for inspection. They have configured a route table on the spoke subnet with a default route (0.0.0.0/0) pointing to the Azure Firewall's private IP as the next hop. However, traffic is still bypassing the firewall. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The route table on the spoke subnet has 'Propagate gateway routes' enabled, causing a conflicting route from the hub's VPN gateway
Option B is correct because when 'Propagate gateway routes' is enabled on the spoke subnet's route table, the VNet peering with the hub (which may have a VPN or ExpressRoute gateway) injects a system route for 0.0.0.0/0 with a next hop of the virtual gateway. This system route has a lower (better) route preference than the user-defined route (UDR) pointing to the Azure Firewall, causing traffic to bypass the firewall and go directly to the gateway.
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.
- ✗
The Azure Firewall subnet is missing a route table entry for the 0.0.0.0/0 route
Why it's wrong here
The firewall subnet itself does not need a default route for spoke traffic; it needs the correct routing to send inspected traffic out. This is not the most likely cause of spoke traffic bypassing.
- ✓
The route table on the spoke subnet has 'Propagate gateway routes' enabled, causing a conflicting route from the hub's VPN gateway
Why this is correct
When gateway propagation is enabled, any routes from the hub's VPN/ExpressRoute gateway are automatically added. These routes can override the custom 0.0.0.0/0 route, especially if the hub has a default route learned via VPN. Disabling propagation resolves the conflict.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The VNet peering does not allow forwarded traffic from the spoke to the firewall
Why it's wrong here
Forwarded traffic is allowed by default when virtual network gateway is not used. The requirement for allowing forwarded traffic is the 'Allow virtual network gateway transit' setting in the hub and 'Use remote virtual network gateways' in the spoke, but this is for gateway transit, not for routing through a firewall instance.
- ✗
The Azure Firewall is not configured with the 'Allow outbound traffic' rule
Why it's wrong here
Firewall rules affect which traffic is allowed, not the routing path. Even without a rule, traffic would still reach the firewall (if routed), but be dropped. The issue is that traffic never reaches the firewall.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a UDR always overrides system routes, but Azure's route selection logic gives system routes (including gateway-propagated routes) higher priority than UDRs for the 0.0.0.0/0 prefix.
Detailed technical explanation
How to think about this question
Azure uses route preference based on the source of the route: system routes (including those propagated from a gateway via BGP) have a lower metric than user-defined routes, so they take precedence. When 'Propagate gateway routes' is enabled on a route table associated with a subnet, any BGP routes learned from a VPN or ExpressRoute gateway in the peered hub VNet are automatically injected as system routes, overriding the UDR for 0.0.0.0/0. This is a common misconfiguration when forcing tunnel traffic through a firewall in a hub-and-spoke topology.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Secure networking — study guide chapter
Learn the concepts, then practise the questions
- →
Secure networking practice questions
Targeted practice on this topic area only
- →
All AZ-500 questions
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Microsoft Azure Security Engineer Associate AZ-500 study guide
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AZ-500 practice test guide
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FAQ
Questions learners often ask
What does this AZ-500 question test?
Secure networking — This question tests Secure networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The route table on the spoke subnet has 'Propagate gateway routes' enabled, causing a conflicting route from the hub's VPN gateway — Option B is correct because when 'Propagate gateway routes' is enabled on the spoke subnet's route table, the VNet peering with the hub (which may have a VPN or ExpressRoute gateway) injects a system route for 0.0.0.0/0 with a next hop of the virtual gateway. This system route has a lower (better) route preference than the user-defined route (UDR) pointing to the Azure Firewall, causing traffic to bypass the firewall and go directly to the gateway.
What should I do if I get this AZ-500 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This AZ-500 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-500 exam.
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