ANS-C01 Question 407
Single answerYou are designing a highly available architecture for a web application hosted on Amazon EC2 instances in a VPC. The application requires a network interface that can failover between instances in different Availability Zones in case of an instance failure. Which type of network interface should you use to achieve this?
- A
Primary network interface
- B
Elastic network interface (ENI)
- C
Secondary network interface
- D
Elastic Fabric Adapter (EFA)
- E
Elastic IP with a network interface
Show answer and explanation
Correct answer: B
Explanation
Elastic Network Interfaces (ENIs) provide the flexibility to detach and reattach between EC2 instances, even across Availability Zones. This makes ENIs the correct choice for designing a failover mechanism in a highly available architecture. Other options either do not support failover or are designed for specialized use cases like high-performance computing.
- A. Incorrect.
A primary network interface is automatically created when an EC2 instance is launched. It cannot be moved or associated with another instance, so it does not support failover across instances.
- B. Correct.
An Elastic Network Interface (ENI) can be detached from one instance and attached to another, even across different Availability Zones, making it suitable for failover scenarios.
- C. Incorrect.
A secondary network interface is an additional ENI attached to an instance. While it provides extra networking capabilities, it does not inherently enable failover between instances.
- D. Incorrect.
Elastic Fabric Adapter (EFA) is designed for high-performance computing and low-latency networking, not for general-purpose failover scenarios involving network interfaces.
- E. Incorrect.
Elastic IP with a network interface allows static IP management but does not inherently enable the network interface to failover between instances.