ANS-C01 Network Implementation Practice Question
A company has a VPC (10.0.0.0/16) with two subnets: public (10.0.1.0/24) and private (10.0.2.0/24). They have an Application Load Balancer (ALB) in the public subnet that distributes traffic to EC2 instances in the private subnet. The ALB is internet-facing and has a security group that allows inbound HTTP/S from 0.0.0.0/0. The EC2 instances have a security group that allows inbound HTTP from the ALB's security group. Users report that they can access the application, but the application is slow and sometimes times out. The network engineer checks CloudWatch metrics and sees that the ALB's target response time is high. The engineer suspects that the EC2 instances are overwhelmed. Which action should the engineer take to improve performance?
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
✓
Add EC2 instances in another Availability Zone and register them with the ALB.
Adding EC2 instances in another Availability Zone increases capacity and distributes traffic across multiple AZs, reducing the load on each instance and improving performance and fault tolerance. Option A is incorrect because a NAT gateway is for outbound internet access, not for reducing latency between ALB and targets. Option B is incorrect because an NLB does not automatically distribute traffic across AZs as effectively for HTTP applications and does not offload processing. Option C is incorrect because simply increasing instance size (vertical scaling) may not provide the same benefits as horizontal scaling across AZs for handling variable loads.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a NAT gateway in the public subnet to reduce latency.
Why it's wrong here
NAT gateway is for outbound internet, not for ALB traffic.
- ✗
Replace the ALB with a Network Load Balancer to reduce overhead.
Why it's wrong here
NLB does not fix instance overload.
- ✗
Increase the size of the EC2 instances in the private subnet.
Why it's wrong here
Scaling up may help but is not the most effective for handling load.
- ✓
Add EC2 instances in another Availability Zone and register them with the ALB.
Why this is correct
Distributing load across AZs improves performance and availability.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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