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ANS-C01 Network Design Practice Question

A company has a VPC with multiple subnets across three Availability Zones. They deploy an Amazon RDS for MySQL Multi-AZ DB instance. The application tier consists of EC2 instances in private subnets. To improve read performance, the company wants to add read replicas. Which THREE design considerations are important for network connectivity? (Choose THREE.)

⚠ Common exam trap

The ANS-C01 exam often tests the misconception that read replicas require public IPs or must be in public subnets, but in reality, they can be deployed in private subnets with proper VPC routing and security group rules.

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

Read replicas can be placed in different Availability Zones than the primary DB instance

Amazon RDS read replicas can be placed in different Availability Zones than the primary DB instance. This improves read performance by distributing read traffic across multiple AZs and provides fault isolation, as replicas remain in the same Region but can be in a different AZ for better availability.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Read replicas can be placed in different Availability Zones than the primary DB instance

    Why this is correct

    Read replicas can be in different AZs to improve availability and fault tolerance.

  • The application EC2 instances must be in the same VPC as the RDS instance

    Why this is correct

    EC2 instances can connect to RDS using private IPs within the same VPC.

  • A security group rule must allow inbound traffic from the application subnets on port 3306

    Why this is correct

    MySQL uses port 3306; the security group must allow traffic from the application tier.

  • Read replicas must be in public subnets with public IP addresses

    Why it's wrong here

    Read replicas should be in private subnets for security; public IPs are not required.

  • Read replicas must be in the same Region as the primary DB instance

    Why it's wrong here

    Read replicas can be in different Regions (cross-Region read replicas).

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This ANS-C01 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 ANS-C01 exam.