Free SAA-C03 Questions Attempt

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.

For maximum resiliency and fault tolerance in a mission-critical scenario, AWS recommends redundant Direct Connect connections from multiple data centers to multiple AWS Direct Connect locations.

This protects against:

Data center failure

Device failure

Location outages

“For workloads that require high availability, we recommend that you use multiple Direct Connect connections at multiple Direct Connect locations.”

— AWS Direct Connect Resiliency Recommendations

Option C follows AWS maximum resiliency model.

This solution directly addresses the scalability and high availability requirements with minimal downtime.

Additional Reader Instances: Adding more reader instances to the Aurora cluster will distribute the read load, improving the performance of the application under heavy read traffic. Aurora reader instances automatically replicate the data from the writer instance, enabling you to scale out read operations.

Amazon RDS Proxy: RDS Proxy improves database availability by managing database connections more efficiently and providing a connection pool. This reduces the overhead on the Aurora cluster during peak loads, further enhancing performance and availability without requiring changes to the application code.

Why Not Other Options?:

Option A (EventBridge and Lambda): This doesn’t directly address the performance and availability issues. Logging state changes and adding reader nodes on failure events doesn’t provide proactive scalability.

Option B (Zero-Downtime Restart and Activity Streams): Zero-Downtime Restart (ZDR) is useful for minimizing downtime during maintenance but doesn’t directly improve scalability. Database Activity Streams are more for security monitoring than for performance enhancement.

Option D (ElastiCache for Redis): While adding a caching layer can help with read performance, it introduces complexity and may not be necessary if additional reader instances can handle the load.

AWS References:

Amazon Aurora Scaling- Information on scaling Aurora clusters with reader instances.

Amazon RDS Proxy- Details on how RDS Proxy can improve database performance and availability.

AWS Site-to-Site VPN: This provides a secure and encrypted connection between an on-premises environment and AWS. It is a cost-effective solution suitable for low bandwidth and small traffic needs.

Quick Setup:

Site-to-Site VPN can be quickly set up by configuring a virtual private gateway on the AWS side and a customer gateway on the on-premises side.

It uses standard IPsec protocol to establish the VPN tunnel.

Cost-Effectiveness: Compared to AWS Direct Connect, which requires dedicated physical connections and higher setup costs, a Site-to-Site VPN is less expensive and easier to implement for smaller traffic requirements.