SAA-C03 Exam Dumps : AWS Certified Solutions Architect - Associate (SAA-C03)

This solution provides the most secure access for external support engineers with the least exposure to potential security risks.

AWS Systems Manager (SSM) and Session Manager: Systems Manager Session Manager allows secure and auditable access to EC2 instances without the need to open inbound SSH ports or manage SSH keys. This reduces the attack surface significantly. The SSM Agent must be installed and configured on all instances, and the instances must have an instance profile with the necessary IAM permissions to connect to Systems Manager.

IAM Identity Center: IAM Identity Center provides centralized management of access to the AWS Management Console for external support engineers. By using IAM Identity Center, youcan control console access securely and ensure that external engineers have the appropriate permissions based on their roles.

Why Not Other Options?:

Option B (Local IAM user credentials): This approach is less secure because it involves managing local IAM user credentials and does not leverage the centralized management and security benefits of IAM Identity Center.

Option C (Security group with SSH access): Allowing SSH access opens up the infrastructure to potential security risks, even when restricted by IP addresses. It also requires managing SSH keys, which can be cumbersome and less secure.

Option D (Bastion host): While a bastion host can secure SSH access, it still requires managing SSH keys and opening ports. This approach is less secure and more operationally intensive compared to using Session Manager.

AWS References:

AWS Systems Manager Session Manager- Documentation on using Session Manager for secure instance access.

AWS IAM Identity Center- Overview of IAM Identity Center and its capabilities for managing user access.

Comprehensive and Detailed Step-by-Step Explanation:

The requirement is toprevent Application A from sending traffic to Application B.

Understanding AWS Network Security Components:

Security Groups

Stateful(if traffic is allowed in one direction, it is automatically allowed in the reverse).

Do not support explicit deny rules, onlyallow rules.

Not suitable for blocking traffic in this scenario.

Network ACLs (NACLs)

Stateless(must define explicit rules for both inbound and outbound traffic).

Support explicit DENY rules.

Best suited for blocking traffic between subnets.

Analysis of the Options:

Option A: Deny Outbound Rule in Security Group for Application B❌(Incorrect)

Security Groups do not support explicit deny rules.

Does not block traffic from Application A to Application B.

Option B: Deny Outbound Rule in Security Group for Application A❌(Incorrect)

Security Groups do not support explicit deny rules.

Cannot effectively prevent Application A from sending traffic to Application B.

Option C: Deny Outbound Rule in NACL for Application B Subnet❌(Incorrect)

This wouldprevent Application B from sending traffic, butthe requirement is to block traffic from Application A to Application B.

Incorrect subnet is being modified.

Option D: Deny Outbound Rule in NACL for Application A Subnet✅(Correct Choice)

Prevents Application A from sending traffic to Application B by blocking outbound requests at the network level.

Effectively stops communication from A to B at the subnet level.

Why Option D is the Best Choice?

✅NACLs support explicit deny rules, unlike security groups.✅Blocks outbound traffic from Application A before it reaches Application B.✅Works at the subnet level, making it scalable.