AWS Certified Advanced Networking Specialty Practice Exam

What AWS feature allows the creation of a dual-homed instance in a VPC?

1. Subnets

2. Elastic Load Balancer

3. Elastic Network Interface

4. NAT Gateway

The correct answer is: Elastic Network Interface

The correct response is that an Elastic Network Interface (ENI) allows for the creation of a dual-homed instance in a Virtual Private Cloud (VPC). An ENI is a virtual network interface that can be attached to an instance in a VPC. When you attach more than one Elastic Network Interface to an instance, you effectively create a dual-homed or multi-homed setup. This allows the instance to connect to multiple subnets or network segments, which can be an essential requirement for scenarios such as high availability, inter-subnet communication, or separating network traffic for security or performance reasons. An instance can have multiple network interfaces, and each ENI can be assigned to different subnets, allowing for flexible networking and configuration options. This capability is vital for distributing workloads across different subnets or providing redundancy if one interface or subnet becomes unavailable. Other options, such as subnets, Elastic Load Balancers, and NAT Gateways, serve different purposes within an AWS environment. Subnets are used to segment a VPC's IP address range, Elastic Load Balancers distribute incoming traffic among multiple instances, and NAT Gateways are used for providing internet access to instances in a private subnet, but none of these features enable an instance to have