DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 developer is troubleshooting an EC2 instance that is unreachable via SSH. The instance passed the status checks, and the security group allows SSH from the developer's IP. What should the developer check next?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The network ACL's outbound rules.
The network ACL is stateless and must allow both inbound and outbound traffic. Option B is correct: the outbound ephemeral port range must be allowed for the return traffic. Option A is wrong because the security group is stateful and allows return traffic automatically. Option C is wrong because the instance is reachable for status checks. Option D is wrong because route tables do not affect direct connectivity to the instance from the internet if it has a public IP.
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.
✗
The security group's outbound rules.
Why it's wrong here
Security groups are stateful; outbound rules do not affect inbound SSH.
✗
The route table for the subnet.
Why it's wrong here
Route tables affect traffic destined for other networks, not direct access to the instance.
✓
The network ACL's outbound rules.
Why this is correct
NACLs are stateless and must allow outbound traffic for the ephemeral ports.
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.
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 DVA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The network ACL's outbound rules. — The network ACL is stateless and must allow both inbound and outbound traffic. Option B is correct: the outbound ephemeral port range must be allowed for the return traffic. Option A is wrong because the security group is stateful and allows return traffic automatically. Option C is wrong because the instance is reachable for status checks. Option D is wrong because route tables do not affect direct connectivity to the instance from the internet if it has a public IP.
What should I do if I get this DVA-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 DVA-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 →
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.
This DVA-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 DVA-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.