Question 291 of 1,170
Implement and Manage Virtual NetworkingmediumMultiple ChoiceObjective-mapped

Using Application Security Groups in NSG Rules

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.

A web tier and an app tier run in separate subnets. Each VM NIC is placed in an application security group named WebASG or AppASG. The administrator must allow only the web tier to reach the app tier on TCP port 8443 and block all other inbound traffic to the app tier. Which NSG rule should be created on the app subnet?

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

Allow TCP 8443 from WebASG to AppASG with a priority lower number than the deny rule.

Option A is correct because NSG rules are evaluated in priority order, with lower numbers having higher priority. By placing an Allow rule for TCP 8443 from WebASG to AppASG with a lower priority number than a subsequent Deny-All rule, only traffic from the web tier is permitted, and all other inbound traffic to the app subnet is blocked. This leverages application security groups (ASGs) to define fine-grained, role-based network security policies without relying on IP addresses.

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.

  • Allow TCP 8443 from WebASG to AppASG with a priority lower number than the deny rule.

    Why this is correct

    This is the most precise approach because it targets the source and destination groups instead of broad IP ranges. The rule must use a lower priority number than the deny-all rule so it is evaluated first. That lets only the web tier reach the app tier on TCP 8443 while preserving the block on all other inbound traffic.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Allow TCP 8443 from the entire virtual network to the app subnet with a lower priority than the deny rule.

    Why it's wrong here

    This would permit more traffic than required because every subnet in the VNet could reach the app tier.

    When this WOULD be correct

    If the requirement were to allow all VMs within the virtual network (e.g., for internal management or inter-tier communication) to reach the app tier on TCP 8443, and only block traffic from outside the virtual network, then allowing from the entire virtual network with a lower priority than a deny-all rule would be correct.

  • Allow UDP 8443 from WebASG to AppASG with any priority below 65000.

    Why it's wrong here

    The protocol is wrong because the application requires TCP, and NSG priority still must beat the deny rule.

    When this WOULD be correct

    If the question required allowing UDP traffic on port 8443 from WebASG to AppASG, and the deny rule had a priority of 65000, then a rule with any priority below 65000 would be correct.

  • Allow TCP 8443 from WebASG to AppASG with a priority higher number than the deny rule.

    Why it's wrong here

    A higher numeric priority is evaluated later, so the deny rule would take effect first and block the traffic.

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.

Allow TCP 8443 from WebASG to AppASG with a priority lower number than the deny rule.Correct answer

Why this is correct

This is the most precise approach because it targets the source and destination groups instead of broad IP ranges. The rule must use a lower priority number than the deny-all rule so it is evaluated first. That lets only the web tier reach the app tier on TCP 8443 while preserving the block on all other inbound traffic.

Allow TCP 8443 from the entire virtual network to the app subnet with a lower priority than the deny rule.Wrong answer — click to see why

Why this is wrong here

This rule allows traffic from the entire virtual network, not just the web tier, violating the requirement to restrict access solely to the web tier. The app subnet would be exposed to all VMs in the virtual network, including potentially malicious or unintended sources.

★ When this WOULD be the correct answer

If the requirement were to allow all VMs within the virtual network (e.g., for internal management or inter-tier communication) to reach the app tier on TCP 8443, and only block traffic from outside the virtual network, then allowing from the entire virtual network with a lower priority than a deny-all rule would be correct.

Why candidates choose this

Candidates may mistakenly think that since the web and app tiers are in the same virtual network, allowing traffic from the entire virtual network is sufficient and simpler. They overlook the need for granular control using application security groups to restrict access to only the web tier.

Allow UDP 8443 from WebASG to AppASG with any priority below 65000.Wrong answer — click to see why

Why this is wrong here

The question specifies TCP port 8443, but option C incorrectly uses UDP. Also, the priority requirement is not about being below 65000; it must be lower than the deny rule's priority.

★ When this WOULD be the correct answer

If the question required allowing UDP traffic on port 8443 from WebASG to AppASG, and the deny rule had a priority of 65000, then a rule with any priority below 65000 would be correct.

Why candidates choose this

Candidates may confuse TCP and UDP ports, or think that any priority below 65000 is sufficient without considering the relative priority to the deny rule.

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?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse priority numbering—thinking a higher number means higher priority—or mistakenly assume that allowing traffic from the entire virtual network is sufficient, overlooking the need to restrict the source to only the web tier via ASGs.

Detailed technical explanation

How to think about this question

Network Security Groups (NSGs) process rules in ascending order of priority (lower number = higher priority), and each rule is evaluated until a match is found; if no rule matches, traffic is denied by default. Application Security Groups (ASGs) allow grouping of VM NICs by application role (e.g., WebASG, AppASG) so that NSG rules can reference these logical groups instead of static IP addresses, simplifying management in dynamic environments. In a real-world scenario, this pattern is commonly used in multi-tier applications where the web tier must communicate with the app tier on a specific port while all other inbound traffic (e.g., from management or other subnets) is explicitly denied.

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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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.

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FAQ

Questions learners often ask

What does this AZ-104 question test?

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: Allow TCP 8443 from WebASG to AppASG with a priority lower number than the deny rule. — Option A is correct because NSG rules are evaluated in priority order, with lower numbers having higher priority. By placing an Allow rule for TCP 8443 from WebASG to AppASG with a lower priority number than a subsequent Deny-All rule, only traffic from the web tier is permitted, and all other inbound traffic to the app subnet is blocked. This leverages application security groups (ASGs) to define fine-grained, role-based network security policies without relying on IP addresses.

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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Same concept, more angles

1 more ways this is tested on AZ-104

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A three-tier application uses separate web and app VMs that are scaled in and out regularly. The administrator must allow only the web tier to connect to the app tier on TCP 8080 without continually updating IP addresses. What should be configured in the NSG rule?

medium
  • A.Use application security groups for the web and app tiers and reference those groups in the NSG rule.
  • B.Add a subnet-to-subnet peering connection between the web and app subnets.
  • C.Create a load balancer backend pool rule for TCP 8080.
  • D.Use a user-defined route that sends TCP 8080 traffic to the app tier.

Why A: Application security groups (ASGs) allow you to group VMs logically by their application role (e.g., web tier, app tier) and reference those groups directly in NSG rules. This eliminates the need to maintain individual IP addresses or CIDR ranges when VMs scale in or out, because the NSG rule dynamically applies to all VMs in the ASG. By creating an inbound NSG rule that allows TCP 8080 from the web-tier ASG to the app-tier ASG, the administrator achieves the required connectivity without manual IP updates.

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Last reviewed: Jun 11, 2026

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