The answer is Azure Web Application Firewall (WAF) on Azure Front Door and Azure SQL Database with Transparent Data Encryption (TDE) and enforced TLS. Azure WAF protects your App Service web application from common web attacks like SQL injection and cross-site scripting (XSS) by inspecting HTTP requests at the application layer, while Azure SQL Database uses TDE to encrypt data at rest and requires TLS enforcement to secure data in transit, ensuring end-to-end encryption. On the Microsoft Cybersecurity Architect exam, this question tests your ability to distinguish between application-layer protections (WAF) and network-layer controls (DDoS Protection or NSGs), a common trap where candidates confuse NSGs with encryption. Remember that WAF is your shield against injection and XSS, while TDE plus TLS is your lockbox for data—think "WAF for the web, TDE+TLS for the database."
SC-100 Practice Question: Design security solutions for applications and data
This SC-100 practice question tests your understanding of design security solutions for applications and data. 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.
You are designing a solution to protect a web application hosted on Azure App Service. The application uses Azure SQL Database and stores sensitive customer data. You need to ensure that the data is encrypted at rest and in transit, and that the application is protected from common web attacks. Which TWO of the following should you implement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enforce TLS for Azure SQL Database connections
Option A and D are correct. Option A: Azure WAF protects against common web attacks like SQL injection and XSS. Option D: Azure SQL Database always encrypts data at rest with TDE, and enforcing TLS ensures encryption in transit. Option B is wrong because DDoS Protection is for network-layer attacks, not application-layer. Option C is wrong because Network Security Groups (NSGs) are for network traffic filtering, not for encrypting data in transit.
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.
✗
Azure Private Link for App Service
Why it's wrong here
Private Link provides private connectivity but does not encrypt data in transit or protect against web attacks.
✓
Enforce TLS for Azure SQL Database connections
Why this is correct
Enforcing TLS encrypts data in transit between App Service and SQL Database; TDE encrypts at rest.
DDoS Protection mitigates distributed denial-of-service attacks, not application-layer attacks.
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
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
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 applications and data — This question tests Design security solutions for applications and data — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Enforce TLS for Azure SQL Database connections — Option A and D are correct. Option A: Azure WAF protects against common web attacks like SQL injection and XSS. Option D: Azure SQL Database always encrypts data at rest with TDE, and enforcing TLS ensures encryption in transit. Option B is wrong because DDoS Protection is for network-layer attacks, not application-layer. Option C is wrong because Network Security Groups (NSGs) are for network traffic filtering, not for encrypting data in transit.
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.
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. You are designing a solution to protect an Azure App Service web application from common web attacks like SQL injection and cross-site scripting. What should you implement?
easy
A.Azure Firewall
B.Azure DDoS Protection
✓ C.Azure Web Application Firewall (WAF) policy on Azure Front Door
D.Network Security Groups (NSGs) on the subnet
Why C: Option A is correct because Azure Web Application Firewall (WAF) with Application Gateway or Front Door protects against SQL injection and XSS. Option B is wrong because Network Security Groups (NSGs) filter network traffic, not application layer. Option C is wrong because Azure DDoS Protection protects against DDoS, not web attacks. Option D is wrong because Azure Firewall is a network firewall, not a web application firewall.
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Question Discussion
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