Quick Answer
The correct answer is that the EC2 instance must have an IAM role that allows SSM actions. This is required because the AWS Systems Manager Session Manager relies on the SSM Agent running on the instance to initiate an outbound connection to the Systems Manager service over the AWS API, and that agent needs an IAM role with permissions like ssm:UpdateInstanceInformation and ssm:SendCommand to authenticate and communicate securely. On the AWS Certified Security Specialty SCS-C02 exam, this concept tests your understanding of how Session Manager achieves secure shell access without opening inbound ports, a common trap being that candidates assume SSH keys or open security groups are necessary. The key memory tip is “IAM role, not inbound hole”—the agent talks out, so the role is the gatekeeper, not the security group.
This SCS-C02 practice question tests your understanding of infrastructure security. 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 company is using AWS Systems Manager Session Manager to provide secure shell access to EC2 instances without opening inbound ports. Which of the following is a requirement for this setup?
The EC2 instance must have an IAM role that allows SSM actions.
The SSM Agent uses the role to communicate with Systems Manager.
The EC2 instance must be in a public subnet.
Why wrong: Session Manager works in private subnets.
The EC2 instance must have a public IP address.
Why wrong: Session Manager works without public IP.
The security group must allow inbound SSH from 0.0.0.0/0.
Why wrong: Session Manager does not require inbound ports.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The EC2 instance must have an IAM role that allows SSM actions.
Option B is correct. Session Manager requires an SSM Agent installed on the EC2 instance and an IAM role that allows the agent to communicate with the Systems Manager service. Option A is not required; Session Manager works without SSH. Option C is not required; Session Manager uses the AWS API. Option D is not required; security groups can still be restrictive.
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
For each option: why learners choose it and why it is or isn't the right answer here.
The EC2 instance must have an IAM role that allows SSM actions.
Why this is correct
The SSM Agent uses the role to communicate with Systems Manager.
Related concept
CIDR notation defines the prefix length.
The EC2 instance must be in a public subnet.
Why it's wrong here
Session Manager works in private subnets.
The EC2 instance must have a public IP address.
Why it's wrong here
Session Manager works without public IP.
The security group must allow inbound SSH from 0.0.0.0/0.
Why it's wrong here
Session Manager does not require inbound ports.
Common exam traps
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
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.
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
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
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
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
The correct answer is: The EC2 instance must have an IAM role that allows SSM actions. — Option B is correct. Session Manager requires an SSM Agent installed on the EC2 instance and an IAM role that allows the agent to communicate with the Systems Manager service. Option A is not required; Session Manager works without SSH. Option C is not required; Session Manager uses the AWS API. Option D is not required; security groups can still be restrictive.
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.
CIDR notation defines the prefix length.
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Same concept, more angles
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 company uses AWS Systems Manager Session Manager to manage EC2 instances without opening inbound ports. Which IAM policy is required for an EC2 instance to allow Session Manager to connect?
easyWhy D: Option C is correct because SSM Agent requires the AmazonSSMManagedInstanceCore policy to communicate with Systems Manager. Option A is wrong because it is for admin users. Option B is wrong because it allows EC2 actions, not SSM. Option D is wrong because it allows full SSM access, which is excessive.
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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.
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