Question 1,439 of 1,738
Security Logging and MonitoringmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is to enable VPC Flow Logs for the subnet and query the logs in CloudWatch Logs Insights for rejected traffic on port 22. This works because VPC Flow Logs capture metadata about all network traffic to and from an EC2 instance, including the destination port and the action taken—either ACCEPT or REJECT. By filtering for REJECT records on port 22, you isolate failed SSH connection attempts at the network level, without needing OS-level access. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of the separation between network-layer monitoring (VPC Flow Logs) and OS-level logging (CloudWatch agent). A common trap is confusing CloudTrail, which logs API calls, with actual network traffic—CloudTrail will not show a rejected SSH handshake. Another pitfall is assuming the CloudWatch agent is the simplest method, but VPC Flow Logs require no installation and capture all traffic automatically. Memory tip: think “Flow for Flows” — VPC Flow Logs handle network flows, not OS logs.

SCS-C02 Security Logging and Monitoring Practice Question

This SCS-C02 practice question tests your understanding of security logging and monitoring. 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.

A security analyst needs to review all failed SSH login attempts to an EC2 instance. Which combination will provide this information?

Question 1mediummultiple choice
Read the full NAT/PAT explanation →

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

Enable VPC Flow Logs for the subnet and query the logs in CloudWatch Logs Insights for rejected traffic on port 22.

Option B is correct because VPC Flow Logs capture network traffic metadata including destination port and action (accept/reject), and CloudWatch Logs Insights can query for SSH traffic (port 22) that was rejected. Option A is incorrect because CloudTrail logs API calls, not OS-level login attempts. Option C is incorrect because CloudWatch agent can collect OS logs but is not the simplest way; VPC Flow Logs are more straightforward. Option D is incorrect because Config does not monitor OS logs.

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.

  • Use AWS Config to record EC2 instance configuration and check for security group changes.

    Why it's wrong here

    AWS Config does not monitor OS-level login attempts.

  • Install the CloudWatch agent on the EC2 instance to collect /var/log/secure and stream to CloudWatch Logs.

    Why it's wrong here

    This can work but requires agent installation and configuration; VPC Flow Logs are simpler and require no agent.

  • Enable AWS CloudTrail and search for EC2-related events.

    Why it's wrong here

    CloudTrail logs API calls, not SSH login attempts.

  • Enable VPC Flow Logs for the subnet and query the logs in CloudWatch Logs Insights for rejected traffic on port 22.

    Why this is correct

    VPC Flow Logs capture metadata of network traffic, including rejected connections; SSH login failures typically show as rejected TCP connections on port 22.

    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 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 SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.

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FAQ

Questions learners often ask

What does this SCS-C02 question test?

Security Logging and Monitoring — This question tests Security Logging and Monitoring — CIDR notation defines the prefix length..

What is the correct answer to this question?

The correct answer is: Enable VPC Flow Logs for the subnet and query the logs in CloudWatch Logs Insights for rejected traffic on port 22. — Option B is correct because VPC Flow Logs capture network traffic metadata including destination port and action (accept/reject), and CloudWatch Logs Insights can query for SSH traffic (port 22) that was rejected. Option A is incorrect because CloudTrail logs API calls, not OS-level login attempts. Option C is incorrect because CloudWatch agent can collect OS logs but is not the simplest way; VPC Flow Logs are more straightforward. Option D is incorrect because Config does not monitor OS logs.

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.

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Last reviewed: Jun 20, 2026

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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.