AWS Classic Load Balancer Subnet Requirements

Answer - D.

This is mentioned in the AWS documentation.

To ensure that your load balancer can scale properly, verify that each subnet for your load balancer has a CIDR block with at least a /27 bitmask (for example, 10.0.0.0/27) and has at least 8 free IP addresses.

Your load balancer uses these IP addresses to establish connections with the instances.

For more information on setting up the instances in an ELB, please visit the below link:

When using the AWS Classic Load Balancer, you will need to deploy it across subnets within a VPC. To use a subnet with a Classic Load Balancer, the subnet must meet certain requirements. One of these requirements is that the subnet must have at least 8 IP addresses available, but only 2 of these will be used by the load balancer.

To determine the minimum subnet mask needed for a subnet to be used with a Classic Load Balancer, we need to calculate how many IP addresses are available in the subnet. We can use the formula 2^(32-n) to calculate the number of available IP addresses in a subnet with a mask of /n.

So let's calculate the number of available IP addresses for each of the subnet masks given in the answer choices:

• A. /30: 2^(32-30) = 4 available IP addresses
• B. /29: 2^(32-29) = 8 available IP addresses
• C. /28: 2^(32-28) = 16 available IP addresses
• D. /27: 2^(32-27) = 32 available IP addresses

As we can see, the minimum number of available IP addresses required for a subnet to be used with a Classic Load Balancer is 8, which means that the minimum subnet mask needed is /29. Therefore, the correct answer is B. /29.