ANS-C01 Network Implementation Practice Question
Which TWO of the following are true about AWS VPC security groups? (Choose two.)
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that security groups are stateless like network ACLs, or that they support deny rules, or that they are associated with subnets, leading candidates to confuse security groups with network ACLs.
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
✓
They have an implicit deny all rule at the end.
Security groups in AWS VPC are stateful, meaning that if you allow inbound traffic, the corresponding outbound return traffic is automatically permitted, regardless of outbound rules. They also have an implicit deny all rule at the end, so any traffic not explicitly allowed by a rule is denied. This makes options B and C correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Rules are evaluated in order, and the first matching rule is applied.
Why it's wrong here
All rules are evaluated; there is no order.
- ✓
They have an implicit deny all rule at the end.
Why this is correct
If no rule matches, traffic is denied.
- ✓
They are stateful, meaning return traffic is automatically allowed regardless of outbound rules.
Why this is correct
Stateful nature allows return traffic.
- ✗
They support both allow and deny rules.
Why it's wrong here
Security groups only support allow rules.
- ✗
They can be associated with subnets.
Why it's wrong here
Security groups are associated with ENIs, not subnets.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 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 ANS-C01 exam.