The answer is to remove the 0.0.0.0/0 user-defined route (UDR) pointing to the virtual appliance. This is correct because a UDR with a destination of 0.0.0.0/0 takes precedence over the system default route that directs traffic to the NAT gateway, effectively blocking outbound internet traffic from using the NAT gateway. On the AZ-104 exam, this scenario tests your understanding of Azure routing precedence, where a more specific or explicit UDR overrides system routes, and it often appears as a common trap where a virtual appliance is mistakenly prioritized for internet-bound traffic. A key memory tip is to remember that for a NAT gateway to handle outbound traffic, the subnet’s effective route for 0.0.0.0/0 must point to the NAT gateway’s private IP, not a virtual appliance—think “NAT needs the default, not a detour.”
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.
Why wrong: Removing the NAT gateway would reduce outbound options, not direct traffic to the desired egress path.
B
Remove the 0.0.0.0/0 user-defined route to the virtual appliance.
A user-defined default route overrides the subnet's normal internet egress behavior and sends traffic to the appliance instead. Removing that route lets the NAT gateway handle outbound connections from the subnet.
C
Change the route table source address to 10.1.0.4.
Why wrong: Route tables do not use a source address field in that way, and this does not alter outbound path selection.
D
Enable a service endpoint on the subnet.
Why wrong: Service endpoints are for access to supported Azure services, not for choosing outbound internet routing.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove the 0.0.0.0/0 user-defined route to the virtual appliance.
The correct answer is B because the user-defined route (UDR) with destination 0.0.0.0/0 pointing to the virtual appliance is overriding the default route to the NAT gateway. For outbound internet traffic to use the NAT gateway, the 0.0.0.0/0 route must point to the NAT gateway's private IP address or be removed entirely so the system route to the NAT gateway takes precedence. Removing this UDR allows the NAT gateway to handle all outbound traffic from the subnet.
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.
✗
Detach the subnet from the NAT gateway.
Why it's wrong here
Removing the NATgateway would reduce outbound options, not direct traffic to the desired egress path.
✓
Remove the 0.0.0.0/0 user-defined route to the virtual appliance.
Why this is correct
A user-defined default route overrides the subnet's normal internet egress behavior and sends traffic to the appliance instead. Removing that route lets the NAT gateway handle outbound connections from the subnet.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the route table source address to 10.1.0.4.
Why it's wrong here
Route tables do not use a source address field in that way, and this does not alter outbound path selection.
✗
Enable a service endpoint on the subnet.
Why it's wrong here
Service endpoints are for access to supported Azure services, not for choosing outbound internet routing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume a NAT gateway automatically handles all outbound traffic without considering that a conflicting user-defined route (0.0.0.0/0) to a virtual appliance will override the NAT gateway's default route, causing traffic to bypass the NAT gateway entirely.
Detailed technical explanation
How to think about this question
Azure NATgateway uses a default system route (0.0.0.0/0) with a next hop type of 'Internet' that is automatically created when the NAT gateway is attached to a subnet. However, any user-defined route (UDR) with the same destination prefix (0.0.0.0/0) takes precedence over the system route, even if the UDR points to a virtual appliance. This is because UDRs have a higher effective priority than system routes, and the route with the most specific match (or, for equal prefixes, the UDR) wins. In real-world scenarios, this often causes silent failures where traffic is sent to a firewall or NVA instead of the NAT gateway, leading to asymmetric routing or dropped connections.
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: Remove the 0.0.0.0/0 user-defined route to the virtual appliance. — The correct answer is B because the user-defined route (UDR) with destination 0.0.0.0/0 pointing to the virtual appliance is overriding the default route to the NAT gateway. For outbound internet traffic to use the NAT gateway, the 0.0.0.0/0 route must point to the NAT gateway's private IP address or be removed entirely so the system route to the NAT gateway takes precedence. Removing this UDR allows the NAT gateway to handle all outbound traffic from the subnet.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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