AZ-104 Implement and Manage Virtual Networking Practice Question
A three-tier application uses separate web and app VMs. The requirement is to allow only the web tier to reach the app tier on TCP 8080. The app subnet NSG already contains a DenyAllInbound rule at priority 200. What should the administrator do?
⚠ Common exam trap
Candidates often think moving the deny rule to a higher priority number (lower priority) will fix the issue, but without an explicit allow rule, traffic remains blocked; or they may confuse user-defined routes (which control routing) with NSG rules (which control filtering).
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
✓
Create an inbound allow rule for the web ASG to the app ASG on TCP 8080 with priority 150.
The existing DenyAllInbound rule at priority 200 will block all traffic to the app subnet unless a higher-priority (lower number) allow rule is created. By creating an inbound allow rule for the web Application Security Group (ASG) to the app ASG on TCP 8080 with priority 150, the administrator ensures that traffic from the web tier is explicitly permitted before the deny rule is evaluated, satisfying the requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create an inbound allow rule for the web ASG to the app ASG on TCP 8080 with priority 150.
Why this is correct
NSG rules are processed in priority order, where the lowest number wins. To permit only web-tier traffic to the app tier while preserving the deny rule, the allow rule must have a higher precedence than the DenyAllInbound entry. Using application security groups keeps the rule maintainable as VMs scale in or out, and the specific source, destination, and port limit access to exactly the required flow.
- ✗
Move the DenyAllInbound rule to priority 300 so all traffic is blocked first.
Why it's wrong here
NSG rules evaluate in ascending priority number, so a rule with priority 150 is processed before one with priority 300. Moving the DenyAllInbound rule to 300 means it would be the last rule evaluated, not the first, so it cannot 'block all traffic first' and would not precede the new allow rule. This reordering would also change how all other inbound rules are evaluated, potentially permitting traffic that should remain denied.
When this WOULD be correct
This option would be correct if the requirement was to ensure that a specific deny rule is evaluated after other rules, for example, to allow logging of denied traffic before the final deny, or to reorder rules for troubleshooting without changing the effective access.
- ✗
Add a user-defined route from the web subnet to the app subnet.
Why it's wrong here
A user-defined route (UDR) only controls the next-hop path for traffic; it does not perform any filtering or access control. Even if a UDR directs web subnet traffic toward the app subnet, the NSG's DenyAllInbound rule will still drop packets destined to TCP 8080 unless an allow rule exists. Therefore, adding a route cannot create the required exception for web-to-app traffic on port 8080.
When this WOULD be correct
A UDR would be correct if the requirement was to force-tunnel traffic from the web subnet to the app subnet through a network virtual appliance (NVA) for inspection, or to override Azure's default routing to direct traffic to a specific next hop.
- ✗
Associate the web and app NICs with the same application security group.
Why it's wrong here
Placing both web and app NICs in the same application security group removes the ability to distinguish the source and destination tiers in an NSG rule. A rule that references that single ASG as both source and destination would apply to any member, allowing web-to-web, app-to-app, and app-to-web traffic on the specified port, violating least privilege. Separate ASGs are required so the rule can explicitly match source=web ASG and destination=app ASG.
When this WOULD be correct
In a scenario where all VMs in the same tier need to communicate freely (e.g., all web servers need to allow all inbound traffic from each other), associating them with the same ASG and creating an allow rule for the ASG would be correct.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.
✓Create an inbound allow rule for the web ASG to the app ASG on TCP 8080 with priority 150.Correct answer▾
Why this is correct
NSG rules are processed in priority order, where the lowest number wins. To permit only web-tier traffic to the app tier while preserving the deny rule, the allow rule must have a higher precedence than the DenyAllInbound entry. Using application security groups keeps the rule maintainable as VMs scale in or out, and the specific source, destination, and port limit access to exactly the required flow.
✗Move the DenyAllInbound rule to priority 300 so all traffic is blocked first.Wrong answer — click to see why▾
Why this is wrong here
Moving the DenyAllInbound rule to a higher priority (300) would not change its effect; it still denies all traffic that is not explicitly allowed. The issue is that no allow rule exists for the web-to-app traffic, so lowering the priority does not create an allow rule.
★ When this WOULD be the correct answer
This option would be correct if the requirement was to ensure that a specific deny rule is evaluated after other rules, for example, to allow logging of denied traffic before the final deny, or to reorder rules for troubleshooting without changing the effective access.
Why candidates choose this
Candidates may think that adjusting priority alone can fix the problem, misunderstanding that NSG rules are evaluated in priority order and that a deny rule at any priority still blocks traffic unless a higher-priority allow rule exists.
✗Add a user-defined route from the web subnet to the app subnet.Wrong answer — click to see why▾
Why this is wrong here
User-defined routes (UDRs) control traffic routing between subnets, not access control. The requirement is to allow or deny traffic based on port and protocol, which is the function of NSG rules, not UDRs.
★ When this WOULD be the correct answer
A UDR would be correct if the requirement was to force-tunnel traffic from the web subnet to the app subnet through a network virtual appliance (NVA) for inspection, or to override Azure's default routing to direct traffic to a specific next hop.
Why candidates choose this
Candidates may confuse routing (UDRs) with access control (NSGs), thinking that directing traffic via a route implicitly allows it, or they may overcomplicate the solution by introducing routing when a simple NSG rule suffices.
✗Associate the web and app NICs with the same application security group.Wrong answer — click to see why▾
Why this is wrong here
Associating web and app NICs with the same ASG would allow all traffic between them, not restrict to TCP 8080 only, and would bypass the DenyAllInbound rule, violating the requirement.
★ When this WOULD be the correct answer
In a scenario where all VMs in the same tier need to communicate freely (e.g., all web servers need to allow all inbound traffic from each other), associating them with the same ASG and creating an allow rule for the ASG would be correct.
Why candidates choose this
Candidates may think that using the same ASG simplifies security by grouping resources, but they overlook that ASGs are used for source/destination filtering, not to automatically allow all traffic between members.
Analysis generated from the official AZ-104blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Related to this question
Learn chapter
Network Security Groups (NSG)
Key term
Security group
A security group is a virtual firewall that controls inbound and outbound traffic to AWS resources, such as EC2 instances, based on defined rules.
Key term
Application Security Group
An Application Security Group (ASG) is a cloud networking feature that groups virtual machines logically and allows you to apply security rules based on the application workload, rather than individual IP addresses.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-104 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-104 exam.