EC2 - Elastic Network Interfaces (ENI)

Question 1

What is an ENI?

Answer 1

An Elastic Network Interface is a logical component in a VPC that represents a virtual network card.

Question 2

List 6 attributes that an ENI may have?

Answer 2

1. Primary private IPv4
2. One or more secondary IPv4
3. One Elastic IPv4 per private IPv4
4. One Public IPv4
5. One or more security groups assigned
6. A MAC address

Question 3

True or False? ENIs can be created independently from an instance and can be moved across other instances within the same AZ?

Answer 3

True

Question 4

True or False? ENIs are bound to a specific AZ.

Answer 4

True

Question 5

Why would you attach a secondary ENI to an Instance?

Answer 5

Incase of network failover. You can move the ENI to another instance that is running the same application so you can access it using the secondary private IPv4.