Question 40 of 969
Design security solutions for infrastructureeasyMultiple ChoiceObjective-mapped

Quick Answer

The answer is that this Azure Policy denies creation of any virtual machine that is attached to a public IP address. It works by evaluating the network interface (NIC) resource associated with a VM; if the NIC’s `id` field is present—indicating a public IP is attached—the policy triggers a deny action, blocking deployment. On the Microsoft Cybersecurity Architect exam, this tests your ability to read policy definitions and understand how Azure Policy evaluates resource properties, often appearing as a scenario where you must distinguish between denying a specific configuration versus a resource type. A common trap is confusing “deny VMs with public IPs” with “deny VMs without NICs” or “deny specific subnets,” but the policy’s logic explicitly targets the NIC’s public IP attachment. Memory tip: think “NIC check equals IP block”—if the NIC has a public IP’s `id`, the VM is denied.

SC-100 Design security solutions for infrastructure Practice Question

This SC-100 practice question tests your understanding of design security solutions for infrastructure. 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": {
    "policyRule": {
      "if": {
        "field": "type",
        "equals": "Microsoft.Compute/virtualMachines"
      },
      "then": {
        "effect": "deny",
        "details": {
          "field": "Microsoft.Compute/virtualMachines/networkProfile.networkInterfaces[*].id"
        }
      }
    }
  }
}

Refer to the exhibit. You are reviewing an Azure Policy definition. What does this policy do?

Question 1easymultiple choice
Full question →

Exhibit

{
  "properties": {
    "policyRule": {
      "if": {
        "field": "type",
        "equals": "Microsoft.Compute/virtualMachines"
      },
      "then": {
        "effect": "deny",
        "details": {
          "field": "Microsoft.Compute/virtualMachines/networkProfile.networkInterfaces[*].id"
        }
      }
    }
  }
}

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

Denies creation of any virtual machine that is attached to a public IP address.

Option A is correct because the policy denies creation of virtual machines that have any network interface (NIC) attached to a public IP (by checking the NIC's id field, which would be present if attached). Option B is wrong because the policy does not target VMs without a NIC. Option C is wrong because the policy denies VMs with NICs, not VMs without NICs. Option D is wrong because the policy does not check for a specific subnet.

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.

  • Denies creation of any virtual machine that has a network interface attached to a specific subnet.

    Why it's wrong here

    The policy does not evaluate subnet.

  • Denies creation of any virtual machine that is attached to a public IP address.

    Why this is correct

    The policy denies VMs where the NIC field is present, which implies public IP attachment.

    Related concept

    CIDR notation defines the prefix length.

  • Denies creation of any virtual machine that does not have a network interface.

    Why it's wrong here

    The policy checks for presence of NIC, not absence.

  • Allows creation of virtual machines only if they have a network interface attached to a specific subnet.

    Why it's wrong here

    The policy is a deny effect, not allow.

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 SC-100 subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this SC-100 question test?

Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: Denies creation of any virtual machine that is attached to a public IP address. — Option A is correct because the policy denies creation of virtual machines that have any network interface (NIC) attached to a public IP (by checking the NIC's id field, which would be present if attached). Option B is wrong because the policy does not target VMs without a NIC. Option C is wrong because the policy denies VMs with NICs, not VMs without NICs. Option D is wrong because the policy does not check for a specific subnet.

What should I do if I get this SC-100 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 SC-100 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 21, 2026

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