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 CloudWatch 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 a NAT instance to an Auto Scaling group does not provide high availability for the web server itself. This will only improve the NAT instance’s availability, not the EC2 instance.
Adding additional EC2 instances across multiple Availability Zones with an Application Load Balancer ensures high availability for the web server, as traffic is distributed and instances are available in different zones.
Configuring an Application Load Balancer in front of the EC2 instance helps with load balancing but does not address the need for high availability of the EC2 instance itself if it fails.
Replacing the NAT instance with a NAT gateway in each Availability Zone ensures that outbound traffic has high availability, as the NAT gateway is distributed across zones.
A single NAT gateway spanning multiple Availability Zones does not ensure high availability for outbound traffic if the gateway fails in one zone. Multiple NAT gateways are needed in different zones for full redundancy.
I would say the answer is:
Create additional EC2 instances spanning multiple Availability Zones. Add an Application Load Balancer to split the load between them.