DBS-C01 Security Group Evaluation Practice Question
This DBS-C01 practice question tests your understanding of database security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: security Group Evaluation. 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.
Network Topology
An RDS DB instance has two security groups attached. Security group sg-12345678 allows inbound traffic on port 3306 from 0.0.0.0/0. Security group sg-87654321 allows inbound traffic on port 3306 from 10.0.0.0/16. What is the effective inbound access to the DB instance?
Network Topology
A
No IP addresses are allowed because the rules conflict.
Why wrong: There is no conflict; rules are combined.
B
Only the 0.0.0.0/0 range is allowed because sg-12345678 is more permissive.
Why wrong: Both groups apply, so 10.0.0.0/16 is also allowed, but 0.0.0.0/0 includes all.
C
Only the 10.0.0.0/16 range is allowed because sg-87654321 is more restrictive.
Why wrong: Security group rules are additive; the broader allow from sg-12345678 also applies.
D
All IP addresses (0.0.0.0/0) are allowed to connect.
Since sg-12345678 allows all traffic, any IP can connect.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
All IP addresses (0.0.0.0/0) are allowed to connect.
Option D is correct. When multiple security groups are attached to an RDS instance, the rules are combined, and the most permissive inbound rule applies. Security group sg-12345678 allows all IP addresses (0.0.0.0/0), so the effective inbound access is from all IPs. Option A is wrong because the rules do not conflict; they are additive. Option B is wrong because the more restrictive rule does not override the more permissive one. Option C is wrong because the less restrictive rule (0.0.0.0/0) applies, not just the 10.0.0.0/16 range.
Key principle: Security Group Evaluation
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
No IP addresses are allowed because the rules conflict.
Why it's wrong here
There is no conflict; rules are combined.
✗
Only the 0.0.0.0/0 range is allowed because sg-12345678 is more permissive.
Why it's wrong here
Both groups apply, so 10.0.0.0/16 is also allowed, but 0.0.0.0/0 includes all.
✗
Only the 10.0.0.0/16 range is allowed because sg-87654321 is more restrictive.
Why it's wrong here
Security group rules are additive; the broader allow from sg-12345678 also applies.
✓
All IP addresses (0.0.0.0/0) are allowed to connect.
Why this is correct
Since sg-12345678 allows all traffic, any IP can connect.
Related concept
Security Group Evaluation
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often mistakenly think that security groups apply only the most restrictive rule, or that rules conflict. In reality, rules are additive and the most permissive rule takes effect.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Security Group Evaluation
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Security Group Evaluation
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Review security Group Evaluation, then practise related DBS-C01 questions on the same topic to reinforce the concept.
Database Security — This question tests Database Security — Security Group Evaluation.
What is the correct answer to this question?
The correct answer is: All IP addresses (0.0.0.0/0) are allowed to connect. — Option D is correct. When multiple security groups are attached to an RDS instance, the rules are combined, and the most permissive inbound rule applies. Security group sg-12345678 allows all IP addresses (0.0.0.0/0), so the effective inbound access is from all IPs. Option A is wrong because the rules do not conflict; they are additive. Option B is wrong because the more restrictive rule does not override the more permissive one. Option C is wrong because the less restrictive rule (0.0.0.0/0) applies, not just the 10.0.0.0/16 range.
What should I do if I get this DBS-C01 question wrong?
Review security Group Evaluation, then practise related DBS-C01 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Security Group Evaluation
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Question Discussion
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