Quick Answer
The answer is Network Security Groups (NSGs). NSGs are the correct choice for filtering traffic between subnets because they act as a stateful, distributed firewall that enforces allow or deny rules based on source, destination, and port, enabling granular network segmentation within a virtual network. On the Microsoft Cybersecurity Architect exam, this question tests your ability to distinguish between Azure’s network security layers: NSGs operate at the subnet and NIC level for east-west traffic control, while Azure Firewall is a centralized, managed service for north-south inspection and is overkill for simple subnet segmentation. A common trap is choosing Azure Firewall for all filtering needs, but remember that NSGs are the native, cost-effective solution for intra-VNet segmentation. Memory tip: NSG stands for “Network Subnet Guard” — think of it as the bouncer at the subnet door, not the whole building.
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.
Your company is migrating to Azure and needs to secure virtual networks with network segmentation. You need to design a solution that filters traffic between subnets based on application requirements. Which Azure service should you use?
Azure DDoS Protection
Why wrong: DDoS Protection defends against volumetric attacks, not traffic filtering.
Azure Firewall
Why wrong: Azure Firewall is a centralized firewall but NSGs are simpler for subnet segmentation.
Azure Bastion
Why wrong: Bastion provides secure RDP/SSH, not network segmentation.
Network Security Groups (NSGs)
NSGs provide stateful filtering between subnets and VMs within a VNet.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Network Security Groups (NSGs)
Option B is correct because Network Security Groups (NSGs) filter traffic between subnets and VMs. Option A is wrong because Azure Firewall is a managed firewall for inbound/outbound but at a higher level. Option C is wrong because Azure DDoS Protection mitigates DDoS attacks, not segmentation. Option D is wrong because Azure Bastion is for secure RDP/SSH access.
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
For each option: why learners choose it and why it is or isn't the right answer here.
Azure DDoS Protection
Why it's wrong here
DDoS Protection defends against volumetric attacks, not traffic filtering.
Azure Firewall
Why it's wrong here
Azure Firewall is a centralized firewall but NSGs are simpler for subnet segmentation.
Azure Bastion
Why it's wrong here
Bastion provides secure RDP/SSH, not network segmentation.
Network Security Groups (NSGs)
Why this is correct
NSGs provide stateful filtering between subnets and VMs within a VNet.
Related concept
CIDR notation defines the prefix length.
Common exam traps
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
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.
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
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.
What to study next
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.
Design security solutions for infrastructure — study guide chapter
Learn the concepts, then practise the questions
Design security solutions for infrastructure practice questions
Targeted practice on this topic area only
All SC-100 questions
969 questions across all exam domains
Microsoft Cybersecurity Architect study guide
Full concept coverage aligned to exam objectives
SC-100 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise SC-100 questions linked to Design solutions that align with security best practices and priorities.
Practise SC-100 questions linked to Design security operations, identity, and compliance capabilities.
Practise SC-100 questions linked to Design security solutions for infrastructure.
Practise SC-100 questions linked to Design a Zero Trust strategy and architecture.
Practise SC-100 questions linked to Design security solutions for applications and data.
Practise SC-100 questions linked to Evaluate GRC and security operations strategies.
Practise SC-100 questions linked to Design security for infrastructure.
Practise SC-100 questions linked to Design a strategy for data and applications.
Practise SC-100 questions linked to Recommend security best practices and priorities.
Practise SC-100 questions linked to SC-100 fundamentals.
Practise SC-100 questions linked to SC-100 scenario.
Practise SC-100 questions linked to SC-100 troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — CIDR notation defines the prefix length..
The correct answer is: Network Security Groups (NSGs) — Option B is correct because Network Security Groups (NSGs) filter traffic between subnets and VMs. Option A is wrong because Azure Firewall is a managed firewall for inbound/outbound but at a higher level. Option C is wrong because Azure DDoS Protection mitigates DDoS attacks, not segmentation. Option D is wrong because Azure Bastion is for secure RDP/SSH access.
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.
CIDR notation defines the prefix length.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 21, 2026
This SC-100 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 SC-100 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.