The answer is 3, because an NSG’s default deny inbound rule already blocks all traffic that isn’t explicitly allowed, so you only need to create explicit allow rules for the three permitted flows: HTTP (port 80) and HTTPS (port 443) from 203.0.113.0/24, and RDP (port 3389) from 10.0.1.0/24. This tests your understanding that NSGs operate on a default-deny model, meaning you never add a separate deny rule for unwanted traffic—the built-in “DenyAllInbound” rule handles that automatically. On the AZ-500 exam, this concept often appears in scenario-based questions where candidates mistakenly add a fourth deny rule, thinking they must explicitly block everything else. A common trap is forgetting that the default rules are already present and have the lowest priority, so your explicit allows simply need higher priority numbers. Memory tip: “Allow only what you need, deny is already done”—the default rule is your silent bouncer.
AZ-500 Secure networking Practice Question
This AZ-500 practice question tests your understanding of secure 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 company has an Azure virtual network with a subnet that hosts a web application. They need to allow inbound HTTP (port 80) and HTTPS (port 443) traffic from a specific source IP range (203.0.113.0/24) to the web servers. Additionally, they need to allow inbound RDP (port 3389) traffic from a management subnet (10.0.1.0/24). They want to block all other inbound traffic. They are using a network security group (NSG) associated with the subnet. What is the minimum number of inbound security rules required?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
3
The correct answer is A (3 rules) because an NSG includes default rules that already block all inbound traffic by default. You only need explicit allow rules for the three permitted traffic types: HTTP (port 80) from 203.0.113.0/24, HTTPS (port 443) from 203.0.113.0/24, and RDP (port 3389) from 10.0.1.0/24. The default deny rule handles blocking all other traffic, so no additional deny rule is required.
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.
✓
3
Why this is correct
Three allow rules (HTTP, HTTPS, RDP) are sufficient. The default deny rule handles all other inbound traffic.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
4
Why it's wrong here
Four rules would be excessive; a rule to deny all traffic is unnecessary because the default deny already exists.
✗
5
Why it's wrong here
Five rules are not needed; only three allow rules are required.
✗
2
Why it's wrong here
Two rules are insufficient because three separate services (HTTP, HTTPS, RDP) must be allowed from different source addresses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think they need an explicit deny rule to block all other traffic, forgetting that the default 'DenyAllInBound' rule already accomplishes this, leading them to overcount the required rules.
Detailed technical explanation
How to think about this question
Azure NSGs have five default inbound rules: three 'AllowVNetInBound', 'AllowAzureLoadBalancerInBound', and 'DenyAllInBound' with priority 65000. Custom rules are evaluated in priority order before the default deny, so only explicit allow rules are needed for permitted traffic. The 'DenyAllInBound' rule at priority 65000 implicitly blocks all traffic not matched by higher-priority allow rules, making an explicit deny rule redundant and unnecessary.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-500 question in full detail.
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: 3 — The correct answer is A (3 rules) because an NSG includes default rules that already block all inbound traffic by default. You only need explicit allow rules for the three permitted traffic types: HTTP (port 80) from 203.0.113.0/24, HTTPS (port 443) from 203.0.113.0/24, and RDP (port 3389) from 10.0.1.0/24. The default deny rule handles blocking all other traffic, so no additional deny rule is required.
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: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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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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 company has an Azure virtual network with a subnet that hosts a public web application. They want to allow inbound HTTPS traffic (port 443) only from the source IP range 203.0.113.0/24, and block all other inbound traffic. They associate a network security group (NSG) with the subnet. What is the minimum number of inbound security rules required in the NSG to achieve this?
easy
A.0 (no additional rules needed because the default rules block all inbound traffic)
✓ B.1
C.2 (one allow rule for HTTPS and one deny rule for all other traffic)
D.3 (one allow HTTPS, one allow for Azure Load Balancer health probes, and one deny all)
Why B: Option B is correct because NSGs include default inbound rules that already block all inbound traffic not explicitly allowed. By adding a single inbound rule to allow HTTPS (port 443) from the source IP range 203.0.113.0/24, all other inbound traffic is implicitly denied by the default deny-all rule (rule 65000). No explicit deny rule is needed, and no additional rules for Azure Load Balancer health probes are required unless the application is behind a load balancer, which is not specified in the scenario.
Variation 2. A company has an Azure virtual network with a subnet that hosts a web application. The security team wants to allow inbound HTTPS traffic (port 443) from the internet to the web servers, but block all other inbound traffic. They have a network security group (NSG) associated with the subnet. What is the minimal set of inbound rules required?
easy
A.A rule allowing HTTPS from Internet, and a default deny all rule.
✓ B.A rule allowing HTTPS from Internet, and no other rules (default deny all inbound).
C.A rule allowing HTTPS from Internet, and a rule explicitly denying all other inbound traffic.
D.A rule allowing HTTPS from any source, and a rule denying all other traffic with lower priority.
Why B: Network security groups (NSGs) in Azure have a default deny-all inbound rule (rule 65500) that is automatically applied to all inbound traffic. Therefore, you only need to add an explicit allow rule for HTTPS (port 443) from the Internet. No additional deny rule is required because the default rule already blocks all other inbound traffic.
Variation 3. A company has an Azure virtual network with a subnet that hosts a web application. They want to allow inbound HTTPS traffic from any source on the internet (0.0.0.0/0) and block all other inbound traffic. They associate a network security group (NSG) with the subnet. What is the minimum number of inbound security rules required to achieve this?
medium
A.One inbound rule allowing HTTPS from Internet, and one inbound rule DenyAllInbound.
✓ B.One inbound rule allowing HTTPS from Internet.
C.Two inbound rules: one allowing HTTPS from Internet, one allowing HTTP from Internet.
D.Two inbound rules: one allowing HTTPS from Internet, one allowing RDP from Internet.
Why B: Option B is correct because an NSG includes a set of default security rules that already block all inbound traffic not explicitly allowed. By adding a single inbound rule that allows HTTPS (TCP port 443) from the Internet (0.0.0.0/0), the default deny rule (DenyAllInbound) will block all other inbound traffic. Therefore, only one custom inbound rule is required to achieve the stated goal.
Variation 4. A company has a virtual network in Azure with a subnet that hosts a web application. They want to allow inbound HTTPS traffic only from a specific source IP range (198.51.100.0/24). They are using Network Security Groups (NSGs) associated with the subnet. What is the minimal set of inbound security rules required?
easy
✓ A.One inbound rule: Allow TCP port 443 from source '198.51.100.0/24'
B.Two inbound rules: one to allow HTTPS, and one to deny all other traffic
C.Three inbound rules: allow HTTPS, allow RDP for management, and deny all
D.One inbound rule: Allow TCP port 443 from source 'Any' and a separate rule to deny from '198.51.100.0/24'
Why A: Option A is correct because NSGs have a default implicit 'DenyAllInbound' rule at the lowest priority (65500). Since you only need to allow HTTPS from the specific source IP range, a single inbound rule permitting TCP port 443 from source '198.51.100.0/24' is sufficient. The implicit deny will block all other traffic, including any traffic from other sources or ports, without needing an explicit deny rule.
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