Which of the following implementation steps can be used to ensure high availability of a NAT instance in AWS.
Choose 2 answers from the options given below.
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A. B. C. D.Answer - C and D.
For an example on high availability for a NAT instance , one can refer to the below URL:
https://aws.amazon.com/articles/high-availability-for-amazon-vpc-nat-instances-an-example/To ensure high availability of a NAT instance in AWS, there are a few implementation steps that can be taken. Two of these steps are:
A. Deploy 2 NAT instances D. Deploy one more NAT instance and ensure that this secondary instance will take over when the Primary NAT instance fails.
Explanation: A NAT instance is a single point of failure in a VPC (Virtual Private Cloud) as it is responsible for forwarding traffic between the instances in a private subnet and the internet. If the NAT instance fails, the instances in the private subnet will not be able to communicate with the internet, causing an outage. Therefore, to ensure high availability of the NAT instance, multiple instances need to be deployed.
Option A suggests deploying two NAT instances. This is a common strategy for high availability of NAT instances. Both instances can be placed in separate availability zones (AZs) to provide redundancy. If one instance fails, the other instance can continue to handle the traffic. However, this approach requires manual intervention to update the route tables of the private subnets to use the active NAT instance.
Option D suggests deploying one more NAT instance and configuring it as a secondary instance that will take over when the primary NAT instance fails. This can be achieved by using Amazon Route 53 health checks or a custom script to monitor the primary NAT instance. If the primary NAT instance fails, the secondary instance can be promoted to handle the traffic automatically.
Option B suggests placing the NAT instances behind an ELB (Elastic Load Balancer). However, this option is not ideal for NAT instances as they have a static IP address and do not support load balancing.
Option C suggests creating a script to monitor the primary NAT instance. Although this can be used in conjunction with Option D, it is not a standalone solution for high availability of a NAT instance.
In summary, the most effective solution for ensuring high availability of a NAT instance in AWS is to deploy multiple NAT instances (Option A or D) and configure them for redundancy.