Ensure Optimal Performance for Instances in VPC Peering

Correct Answers - B and C.

The AWS documentation mentions the following on placement groups/

A placement group is a logical grouping of instances within a single Availability Zone.

Placement groups are recommended for applications that are benefited from low network latency, high network throughput or both.

To provide the lowest latency, and the highest packet-per-second network performance for your placement group, choose an instance type that supports enhanced networking.

For more information on placement groups please refer to the below URL:

To ensure optimal performance for instances launched in two VPCs with a peering connection, the following steps should be taken:

1. Ensure that the instances are launched in subnets in different AZs and create a placement group: When instances are launched in subnets in different AZs, they are spread across multiple physical locations, which helps to ensure high availability and fault tolerance. Additionally, creating a placement group ensures that the instances are placed on the same hardware, reducing the likelihood of network congestion.

2. Ensure that the instance type supports enhanced networking: Enhanced networking uses high-performance network interfaces to provide improved network performance for Amazon EC2 instances. When selecting an instance type, it is important to choose one that supports enhanced networking.

Explanation of options:

A. Ensure that the instances are launched in subnets in different AZ's and create a placement group: This option is correct because launching instances in subnets in different AZs ensures high availability and fault tolerance, while creating a placement group ensures that the instances are placed on the same hardware, reducing the likelihood of network congestion.

B. Ensure that the instances are launched in subnets in the same AZ and create a placement group: This option is not optimal because launching instances in subnets in the same AZ can result in a single point of failure, and it may not provide the fault tolerance and high availability that are required.

C. Ensure that the instance type supports enhanced networking: This option is correct because enhanced networking uses high-performance network interfaces to provide improved network performance for Amazon EC2 instances.

D. Ensure that the MTU for the ENI is set to 1500 for the instances: This option is not necessary for ensuring optimal performance for instances launched in two VPCs with a peering connection. The MTU setting is important for configuring network performance, but it is not directly related to VPC peering performance.