- A
Use AWS Systems Manager Session Manager, enabling the required SSM permissions in the instance profile and restricting access to engineers via IAM.
Session Manager avoids inbound SSH from the internet by initiating interactive sessions through Systems Manager. The instance profile must allow SSM actions like StartSession, and engineers’ IAM permissions restrict who can connect. This is a commonly recommended bastion-free alternative that improves security and reduces exposed network paths.
- B
Keep the bastion host but move it into a private subnet; engineers can connect by using a corporate VPN into the VPC.
Why wrong: A bastion host remains a high-value target and still requires controlled network access. Even if the bastion is private, inbound connectivity and SSH exposure remain. Session Manager provides a more direct elimination of the bastion as well as auditability.
- C
Attach a public IP to each private instance so engineers can SSH directly and use security groups to restrict access.
Why wrong: Public IPs for instances in private subnets defeat the private-subnet isolation and increase attack surface. While security groups could limit access, it’s still direct internet exposure rather than brokered, permissioned management via AWS SSM.
- D
Create a security group rule that allows engineers’ source IP addresses to reach instances over RDP on port 3389.
Why wrong: Allowing RDP with IP-based controls still requires a management network path and does not remove exposure. It also doesn’t align with using AWS SSO-based authentication for secure access auditing and operational workflows.
Quick Answer
The answer is AWS Systems Manager Session Manager, the best bastion host alternative for EC2 access without a public IP. This is correct because Session Manager establishes a secure, agent-based tunnel through the AWS SSM service, eliminating the need for a bastion host, public IPs, or open inbound ports. Since your instances already have an instance profile, you simply attach the AmazonSSMManagedInstanceCore policy to grant SSM permissions, then use IAM policies to restrict access to engineers authenticated via AWS SSO. On the SAA-C03 exam, this scenario tests your understanding of removing legacy bastion hosts while maintaining secure, auditable, on-demand troubleshooting—a common trap is choosing a VPN or a NAT instance instead, which still require network infrastructure. Memory tip: think “SSM = no SSH, no bastion, no public IP.”
SAA-C03 Design Secure Architectures Practice Question
This SAA-C03 practice question tests your understanding of design secure architectures. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: session Manager uses the SSM Agent for outbound communication to AWS endpoints.. 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 team wants to remove a bastion host used for administrative access to EC2 instances in private subnets. The instances should be reachable only for occasional troubleshooting by engineers who authenticate with AWS SSO. What is the best secure alternative within AWS, assuming the instances already have an instance profile attached?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Use AWS Systems Manager Session Manager, enabling the required SSM permissions in the instance profile and restricting access to engineers via IAM.
AWS Systems Manager Session Manager provides secure, auditable, agent-based access to EC2 instances without requiring a bastion host, public IPs, or open inbound ports. Since the instances already have an instance profile, you only need to add the required SSM permissions (e.g., AmazonSSMManagedInstanceCore) to that profile and use IAM policies to restrict Session Manager access to engineers authenticated via AWS SSO. This eliminates the bastion host while maintaining secure, on-demand troubleshooting access.
Key principle: Session Manager uses the SSM Agent for outbound communication to AWS endpoints.
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 Systems Manager Session Manager, enabling the required SSM permissions in the instance profile and restricting access to engineers via IAM.
Why this is correct
Session Manager avoids inbound SSH from the internet by initiating interactive sessions through Systems Manager. The instance profile must allow SSM actions like StartSession, and engineers’ IAM permissions restrict who can connect. This is a commonly recommended bastion-free alternative that improves security and reduces exposed network paths.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Session Manager uses the SSM Agent for outbound communication to AWS endpoints.
- ✗
Keep the bastion host but move it into a private subnet; engineers can connect by using a corporate VPN into the VPC.
Why it's wrong here
A bastion host remains a high-value target and still requires controlled network access. Even if the bastion is private, inbound connectivity and SSH exposure remain. Session Manager provides a more direct elimination of the bastion as well as auditability.
- ✗
Attach a public IP to each private instance so engineers can SSH directly and use security groups to restrict access.
Why it's wrong here
Public IPs for instances in private subnets defeat the private-subnet isolation and increase attack surface. While security groups could limit access, it’s still direct internet exposure rather than brokered, permissioned management via AWS SSM.
- ✗
Create a security group rule that allows engineers’ source IP addresses to reach instances over RDP on port 3389.
Why it's wrong here
Allowing RDP with IP-based controls still requires a management network path and does not remove exposure. It also doesn’t align with using AWS SSO-based authentication for secure access auditing and operational workflows.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think a bastion host is the only way to access private instances, overlooking that AWS Systems Manager Session Manager provides a fully managed, agent-based alternative that eliminates the need for any bastion host or open inbound ports.
Detailed technical explanation
How to think about this question
Session Manager uses the SSM Agent (pre-installed on Amazon Linux 2 and later) to establish a bidirectional WebSocket connection over HTTPS (port 443) to the AWS Systems Manager service, requiring no inbound security group rules. The instance profile must include the ssm:UpdateInstanceInformation, ssm:ListInstanceAssociations, and ssm:DescribeInstanceAssociations actions, typically via the AmazonSSMManagedInstanceCore policy. IAM policies can further restrict which engineers can start sessions and which instances they can access, and all session activity is logged to AWS CloudTrail for auditing.
KKey Concepts to Remember
- Session Manager uses the SSM Agent for outbound communication to AWS endpoints.
- No inbound ports (SSH/RDP) need to be open on the EC2 instances.
- Instance profiles grant EC2 instances permissions to communicate with SSM.
- IAM policies control user access to start and manage sessions.
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
Session Manager uses the SSM Agent for outbound communication to AWS endpoints.
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 session Manager uses the SSM Agent for outbound communication to AWS endpoints., then practise related SAA-C03 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this SAA-C03 question test?
Design Secure Architectures — This question tests Design Secure Architectures — Session Manager uses the SSM Agent for outbound communication to AWS endpoints..
What is the correct answer to this question?
The correct answer is: Use AWS Systems Manager Session Manager, enabling the required SSM permissions in the instance profile and restricting access to engineers via IAM. — AWS Systems Manager Session Manager provides secure, auditable, agent-based access to EC2 instances without requiring a bastion host, public IPs, or open inbound ports. Since the instances already have an instance profile, you only need to add the required SSM permissions (e.g., AmazonSSMManagedInstanceCore) to that profile and use IAM policies to restrict Session Manager access to engineers authenticated via AWS SSO. This eliminates the bastion host while maintaining secure, on-demand troubleshooting access.
What should I do if I get this SAA-C03 question wrong?
Review session Manager uses the SSM Agent for outbound communication to AWS endpoints., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Session Manager uses the SSM Agent for outbound communication to AWS endpoints.
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Last reviewed: Jun 11, 2026
This SAA-C03 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 SAA-C03 exam.
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