ENI

Question 1

How do you calculate subnet range needs?

Answer 1

“x.x.x.x /
each x is a block of 8 bits (00000000)
the value after the slash represents how many bits from left to right are turned on (/4 11110000)
The closed bits remaining comprise the available ip addresses in the block
Projected peak concurrent executions * (Memory in GB / 3GB) = number of IP addresses needed”

Question 2

What are common CIDR ranges to know?

Answer 2

“/24 comes with 256 IP addresses with 251 available
/25 comes with 128 IP addresses with 123 available
/26 comes with 64 IP addresses with 59 available
/27 comes with 32 IP addresses with 27 available”

Question 3

What is Elastic Network Interface?

Answer 3

“A logical networking component in a VPC that represents a virtual network card
connecting a computer to a network”