ANS-C01 Network Design Practice Question
A company is designing a network for a VPC with a CIDR of 10.0.0.0/16. The VPC has three private subnets in three different Availability Zones. The company needs to provide internet access to instances in the private subnets for software updates. The architecture must be highly available and cost-effective. Which TWO actions should the network engineer take?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that a single NAT Gateway is sufficient for high availability, but the trap here is that a NAT Gateway is an AZ-scoped resource, so you need one per AZ to avoid a single point of failure and cross-AZ data transfer costs.
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
✓
Configure each private subnet's route table to route 0.0.0.0/0 to the NAT Gateway in the same Availability Zone.
Configuring each private subnet's route table to route 0.0.0.0/0 to the NAT Gateway in the same Availability Zone ensures that traffic from instances in that subnet uses a NAT Gateway that is in the same AZ, avoiding cross-AZ data transfer costs and maintaining high availability. Option C is correct because deploying a NAT Gateway in each Availability Zone provides redundancy; if one AZ fails, the other NAT Gateways continue to provide internet access, meeting the high availability requirement while remaining cost-effective compared to using NAT instances with Auto Scaling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure each private subnet's route table to route 0.0.0.0/0 to the NAT Gateway in the same Availability Zone.
Why this is correct
This ensures traffic uses the NAT Gateway in the same AZ.
- ✗
Use a NAT instance in an Auto Scaling group.
Why it's wrong here
NAT instances are less reliable than NAT Gateways.
- ✓
Deploy a NAT Gateway in each Availability Zone.
Why this is correct
This provides high availability; each AZ has its own NAT Gateway.
- ✗
Use a single route table for all private subnets and route to one NAT Gateway.
Why it's wrong here
This would force all traffic through one NAT Gateway, reducing availability.
- ✗
Deploy a single NAT Gateway in one Availability Zone.
Why it's wrong here
Single NAT Gateway is a single point of failure.
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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.