Which combination of architecture adjustments should the company implement to achieve high availability?
(Choose two.)
Add the NAT instance to an EC2 Auto Scaling group that spans multiple Availability Zones. Update the route tables.
Create additional EC2 instances spanning multiple Availability Zones. Add an Application Load Balancer to split the load between them.
Configure an Application Load Balancer in front of the EC2 instance. Configure Amazon Cloud Watch alarms to recover the EC2 instance upon host failure.
Replace the NAT instance with a NAT gateway in each Availability Zone. Update the route tables.
Replace the NAT instance with a NAT gateway that spans multiple Availability Zones. Update the route tables.
Explanations:
Adding the NAT instance to an Auto Scaling group is not an ideal solution for high availability. NAT instances should be placed in multiple Availability Zones but not necessarily in Auto Scaling groups.
Creating additional EC2 instances in multiple Availability Zones and using an Application Load Balancer ensures high availability for the web application, as it spreads the load across multiple instances.
An Application Load Balancer can help with routing, but it does not directly solve high availability for outbound internet access, and CloudWatch alarms can only restart an EC2 instance, which is not enough for ensuring overall high availability.
Replacing the NAT instance with a NAT gateway in each Availability Zone ensures high availability for outbound internet access by using the built-in resilience of NAT gateways across multiple Availability Zones.
A single NAT gateway that spans multiple Availability Zones does not provide true high availability. Each Availability Zone should have its own NAT gateway for fault tolerance.
I outline that the answer is:
Create additional EC2 instances spanning multiple Availability Zones. Add an Application Load Balancer to split the load between them.