- A
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG CIDR. DB SG: allow MySQL from App SG CIDR.
Why wrong: Using CIDR is less precise; security group references are preferred.
- B
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow all traffic from Web SG. DB SG: allow MySQL from App SG.
Why wrong: Allowing all traffic from Web SG to App SG is overly permissive.
- C
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from 10.0.0.0/24.
Why wrong: Using CIDR for DB SG is less secure than using security group ID.
- D
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from App SG security group ID.
Security group references ensure only instances in the web tier can access the app tier, and only instances in the app tier can access the database.
Quick Answer
The correct answer is the configuration that uses security group IDs as references for inter-tier traffic, specifically allowing HTTP/HTTPS from 0.0.0.0/0 on the web SG, HTTP from the web SG ID on the app SG, and MySQL from the app SG ID on the DB SG. This is the most secure approach because security group references are stateful and dynamic—they automatically update as instances are added or removed, unlike static CIDR ranges which can become stale or overly broad. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of the principle of least privilege and the proper use of security group chaining in multi-tier architectures. A common trap is choosing CIDR-based rules for internal tiers, which reduces security by exposing IP ranges unnecessarily. Remember the memory tip: “Reference the group, not the range—keep your tiers out of danger.”
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 security engineer is designing a multi-tier web application on AWS. The web tier must be accessible from the internet, but the application tier should be accessible only from the web tier. The database tier should be accessible only from the application tier. Which combination of security groups provides the MOST secure configuration?
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
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from App SG security group ID.
Option D is correct because it uses specific security group references, which are more secure than CIDR ranges. Option A is wrong because it uses CIDR for the web tier, which is less specific. Option B is wrong because it allows all traffic from the web tier. Option C is wrong because it uses CIDR for the database tier.
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.
- ✗
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG CIDR. DB SG: allow MySQL from App SG CIDR.
Why it's wrong here
Using CIDR is less precise; security group references are preferred.
- ✗
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow all traffic from Web SG. DB SG: allow MySQL from App SG.
Why it's wrong here
Allowing all traffic from Web SG to App SG is overly permissive.
- ✗
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from 10.0.0.0/24.
Why it's wrong here
Using CIDR for DB SG is less secure than using security group ID.
- ✓
Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from App SG security group ID.
Why this is correct
Security group references ensure only instances in the web tier can access the app tier, and only instances in the app tier can access the database.
Related concept
CIDR notation defines the prefix length.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
- →
Infrastructure Security — study guide chapter
Learn the concepts, then practise the questions
- →
Infrastructure Security practice questions
Targeted practice on this topic area only
- →
All SCS-C02 questions
1,738 questions across all exam domains
- →
AWS Certified Security Specialty SCS-C02 study guide
Full concept coverage aligned to exam objectives
- →
SCS-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related SCS-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Threat Detection and Incident Response practice questions
Practise SCS-C02 questions linked to Threat Detection and Incident Response.
Security Logging and Monitoring practice questions
Practise SCS-C02 questions linked to Security Logging and Monitoring.
Identity and Access Management practice questions
Practise SCS-C02 questions linked to Identity and Access Management.
Management and Security Governance practice questions
Practise SCS-C02 questions linked to Management and Security Governance.
Infrastructure Security practice questions
Practise SCS-C02 questions linked to Infrastructure Security.
Data Protection practice questions
Practise SCS-C02 questions linked to Data Protection.
SCS-C02 fundamentals practice questions
Practise SCS-C02 questions linked to SCS-C02 fundamentals.
SCS-C02 scenario practice questions
Practise SCS-C02 questions linked to SCS-C02 scenario.
SCS-C02 troubleshooting practice questions
Practise SCS-C02 questions linked to SCS-C02 troubleshooting.
Practice this exam
Start a free SCS-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this SCS-C02 question test?
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Web SG: allow HTTP/HTTPS from 0.0.0.0/0. App SG: allow HTTP from Web SG security group ID. DB SG: allow MySQL from App SG security group ID. — Option D is correct because it uses specific security group references, which are more secure than CIDR ranges. Option A is wrong because it uses CIDR for the web tier, which is less specific. Option B is wrong because it allows all traffic from the web tier. Option C is wrong because it uses CIDR for the database tier.
What should I do if I get this SCS-C02 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 SCS-C02 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
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 →
Same concept, more angles
1 more ways this is tested on SCS-C02
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 security engineer is configuring a VPC for a three-tier application. The web tier must be accessible from the internet, the application tier must be accessible only from the web tier, and the database tier must be accessible only from the application tier. Which TWO security group configurations should be used? (Choose TWO.)
medium- A.Allow inbound SSH from 0.0.0.0/0 on the web tier security group.
- ✓ B.Allow inbound HTTP/HTTPS from 0.0.0.0/0 on the web tier security group.
- C.Allow inbound HTTP/HTTPS from the web tier security group on the database tier security group.
- ✓ D.Allow inbound HTTP/HTTPS from the web tier security group on the application tier security group.
- E.Allow inbound HTTP/HTTPS from the internet on the database tier security group.
Why B: Option A is correct because the web tier security group should allow HTTP/HTTPS from the internet. Option D is correct because the application tier security group should allow traffic from the web tier security group. Option B is wrong because the database tier should not allow traffic from the web tier. Option C is wrong because the web tier should not allow SSH from the internet. Option E is wrong because the database tier should not allow traffic from the internet.
Keep practising
More SCS-C02 practice questions
- Drag and drop the steps to configure AWS WAF with rate-based rules in the correct order.
- Drag and drop the steps to set up AWS Shield Advanced with automatic application layer DDoS mitigation in the correct or…
- Drag and drop the steps to implement AWS KMS key rotation in the correct order.
- Drag and drop the steps to configure a VPC with private subnets and NAT gateway for outbound internet access in the corr…
- Drag and drop the steps to configure AWS CloudTrail for logging across all regions and accounts in the correct order.
- Drag and drop the steps to set up a secure S3 bucket with encryption and access control in the correct order.
Last reviewed: Jun 20, 2026
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services 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 SCS-C02 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.