This blog is a part of my journey “Embarking on the AWS Solution Architect Associate SAA-CO3 Certification Journey”

Elastic IPs

In the dynamic world of cloud computing, where resources can be created, modified, and deleted at a moment’s notice, having a static and reliable way to connect to your cloud-based assets is essential. Enter Elastic IPs, often referred to as EIPs. In this introduction, we’ll explore what Elastic IPs are and why they are a valuable asset in cloud infrastructure.

Introductory Points

1. Dynamic IP Addresses: When you stop and then start an EC2 instance in AWS, it might get assigned a different public IP address.
2. Need for IP Stability: If you require a consistent and unchanging public IP address for your AWS instance, you’ll want to use an Elastic IP.
3. Single Instance Association: An Elastic IP can be associated with one EC2 instance at a time.
4. Enhancing Redundancy: Elastic IP addresses provide a means to enhance the resilience of your AWS infrastructure. If an instance or software fails, you can swiftly remap the Elastic IP to another instance within your AWS account.
5. Limit of 5 Elastic IPs: AWS allows a maximum of five Elastic IP addresses per AWS account.
6. Best Practices to Avoid Elastic IPs:
   • Architectural Decisions: Relying heavily on Elastic IP addresses might suggest a need for a reevaluation of your system’s architecture.
   • Alternative Approaches: Instead of Elastic IPs, consider using random public IP addresses in conjunction with Domain Name System (DNS) registration.
   • Load Balancers: Leverage AWS load balancers to distribute traffic efficiently among instances, reducing the need for Elastic IPs in certain scenarios.

Elastic Network Interfaces (ENIs)

1. Logical component in VPC that represents a virtual network card.
2. The ENI can have following attributes
   • Primary Private IPv4, one more more secondary private IPv4
   • One Elastic IP per private IPv4
   • One public IPv4
   • One or more security groups
   • A MAC address
3. ENIs are also flexible. You can unplug an ENI from one server and plug it into another, like moving a network cable from one computer to another. This is handy if one server has a problem, and you want to quickly switch to another.
4. They are bound to specific Availability Zone