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Question 83 of 1,000
Secure networking →easyMultiple ChoiceObjective-mapped

Quick Answer

The answer is that traffic is allowed by default between subnets. This is because Network Security Groups (NSGs) operate with a set of default rules that permit all inbound and outbound traffic within a virtual network, including traffic flowing between different subnets. Even when each subnet has its own NSG, the default rules do not block inter-subnet communication; they only block inbound traffic from the internet and allow outbound internet traffic. On the Microsoft Azure Security Engineer Associate AZ-500 exam, this concept tests your understanding of NSG default rule precedence and the common misconception that separate NSGs automatically isolate subnets. A frequent trap is assuming that applying any NSG to a subnet creates an implicit block, but in reality, the default allow rule for virtual network traffic remains in effect unless explicitly overridden with a higher-priority deny rule. Memory tip: think of NSG default rules as a “permit-first” firewall—they always allow VNet traffic until you write a specific deny.

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.

Exhibit

{
  "properties": {
    "addressSpace": {
      "addressPrefixes": ["10.0.0.0/16"]
    },
    "subnets": [
      {
        "name": "subnetA",
        "properties": {
          "addressPrefix": "10.0.1.0/24",
          "networkSecurityGroup": {
            "id": "/subscriptions/.../nsgA"
          }
        }
      },
      {
        "name": "subnetB",
        "properties": {
          "addressPrefix": "10.0.2.0/24",
          "networkSecurityGroup": {
            "id": "/subscriptions/.../nsgB"
          }
        }
      }
    ]
  }
}

Refer to the exhibit. You have a VNet with two subnets, each with a different NSG. Both NSGs have default rules. What is the default connectivity between VMs in subnetA and subnetB?

Question 1easymultiple choice
Review the full subnetting walkthrough →

Exhibit

{
  "properties": {
    "addressSpace": {
      "addressPrefixes": ["10.0.0.0/16"]
    },
    "subnets": [
      {
        "name": "subnetA",
        "properties": {
          "addressPrefix": "10.0.1.0/24",
          "networkSecurityGroup": {
            "id": "/subscriptions/.../nsgA"
          }
        }
      },
      {
        "name": "subnetB",
        "properties": {
          "addressPrefix": "10.0.2.0/24",
          "networkSecurityGroup": {
            "id": "/subscriptions/.../nsgB"
          }
        }
      }
    ]
  }
}

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

✓

Traffic is allowed by default.

Option B is correct because by default, NSGs allow all traffic within a VNet, including between subnets. Option A is wrong because there is no default block. Option C is wrong because default rules allow traffic. Option D is wrong because default rules allow traffic.

Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✗

    Traffic is blocked by default.

    Why it's wrong here

    Default NSG rules allow all traffic within a VNet.

  • ✗

    Traffic is allowed only if the VNet has peering.

    Why it's wrong here

    Peering is not required for intra-VNet traffic.

  • ✓

    Traffic is allowed by default.

    Why this is correct

    Default rules permit all internal VNet traffic.

    Related concept

    CIDR notation defines the prefix length.

  • ✗

    Traffic is allowed only if the subnets are in the same region.

    Why it's wrong here

    Region does not affect default NSG rules.

Common exam traps

Common exam trap: usable hosts are not the same as total addresses

Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.

Detailed technical explanation

How to think about this question

Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.

KKey Concepts to Remember

  • CIDR notation defines the prefix length.
  • Block size helps identify subnet boundaries.
  • Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
  • The required host count determines the smallest suitable subnet.

TExam Day Tips

  • Write the block size before choosing the subnet.
  • Check whether the question asks for hosts, subnets or a specific address range.
  • Do not confuse /24, /25, /26 and /27 host counts.

Key takeaway

Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

What to study next

Got this wrong? Here's your next step.

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related AZ-500 subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this AZ-500 question test?

Secure networking — This question tests Secure networking — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: Traffic is allowed by default. — Option B is correct because by default, NSGs allow all traffic within a VNet, including between subnets. Option A is wrong because there is no default block. Option C is wrong because default rules allow traffic. Option D is wrong because default rules allow traffic.

What should I do if I get this AZ-500 question wrong?

Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related AZ-500 subnetting questions on CIDR, address ranges, and subnet selection.

What is the key concept behind this question?

CIDR notation defines the prefix length.

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Last reviewed: Jun 20, 2026

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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.