- A
Launch a single RDS instance in a public subnet and use Route 53 latency-based routing to direct traffic.
Why wrong: RDS should not be in a public subnet; also single instance is not highly available.
- B
Use a Network Load Balancer in front of the RDS instance to distribute connections across Availability Zones.
Why wrong: RDS does not sit behind a Network Load Balancer; it uses its own endpoint and Multi-AZ.
- C
Place the RDS instance in a single Availability Zone and use a read replica in another AZ for failover.
Why wrong: A single AZ for the primary instance is a single point of failure; failover to a read replica takes time.
- D
Create an RDS Multi-AZ cluster with one writer and two reader instances in different AZs, and use the cluster endpoint for writes and reader endpoint for reads.
Multi-AZ cluster provides automatic failover and low-latency reads across AZs.
Quick Answer
The correct answer is to create an RDS Multi-AZ cluster with one writer and two reader instances in different AZs, using the cluster endpoint for writes and the reader endpoint for reads. This configuration provides the most resilient and performant network connectivity because the RDS Multi-AZ high availability architecture ensures synchronous replication across three Availability Zones, eliminating a single point of failure while the separate reader endpoint allows application instances in any AZ to query the nearest reader for low-latency reads. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how to decouple write and read traffic in a multi-AZ deployment, with a common trap being the mistaken belief that a single RDS instance with a standby in another AZ offers the same read performance—it does not, as the standby cannot serve reads. A useful memory tip is to think of the cluster as a “three-legged stool” for resilience, and remember that the reader endpoint is your key to low-latency reads across AZs.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 designing a network architecture for a critical application that requires high availability and low latency. The application will be deployed on EC2 instances in an Auto Scaling group across three Availability Zones in a single region. The instances will communicate with an Amazon RDS database. Which configuration will provide the MOST resilient and performant network connectivity?
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
Create an RDS Multi-AZ cluster with one writer and two reader instances in different AZs, and use the cluster endpoint for writes and reader endpoint for reads.
Placing RDS in a database subnet group across multiple AZs and using a cluster with Multi-AZ provides high availability and low latency by ensuring the database endpoint is always in the same AZ as the application instance when possible. Option A is wrong because a single AZ creates a single point of failure. Option B is wrong because a Network Load Balancer for RDS is not standard. Option D is wrong because a single RDS instance in one AZ is not highly available.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Launch a single RDS instance in a public subnet and use Route 53 latency-based routing to direct traffic.
Why it's wrong here
RDS should not be in a public subnet; also single instance is not highly available.
- ✗
Use a Network Load Balancer in front of the RDS instance to distribute connections across Availability Zones.
Why it's wrong here
RDS does not sit behind a Network Load Balancer; it uses its own endpoint and Multi-AZ.
- ✗
Place the RDS instance in a single Availability Zone and use a read replica in another AZ for failover.
Why it's wrong here
A single AZ for the primary instance is a single point of failure; failover to a read replica takes time.
- ✓
Create an RDS Multi-AZ cluster with one writer and two reader instances in different AZs, and use the cluster endpoint for writes and reader endpoint for reads.
Why this is correct
Multi-AZ cluster provides automatic failover and low-latency reads across AZs.
Related concept
CIDR notation defines the prefix length.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
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
How to think about this question
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.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create an RDS Multi-AZ cluster with one writer and two reader instances in different AZs, and use the cluster endpoint for writes and reader endpoint for reads. — Placing RDS in a database subnet group across multiple AZs and using a cluster with Multi-AZ provides high availability and low latency by ensuring the database endpoint is always in the same AZ as the application instance when possible. Option A is wrong because a single AZ creates a single point of failure. Option B is wrong because a Network Load Balancer for RDS is not standard. Option D is wrong because a single RDS instance in one AZ is not highly available.
What should I do if I get this ANS-C01 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
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.
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