AWS Certified Solutions Architect - Associate Exam: Identify IP Addresses for Auto Scaling Instances

Identifying IP Addresses for Auto Scaling Instances

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Question

Your company runs an automobile reselling company that has a popular online store on AWS.

The application sits behind an Auto Scaling group and requires new instances of the Auto Scaling group to identify their public and private IP addresses.

Which of the following is the correct AWS option to identify the IP addresses?

Answers

Explanations

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A. B. C. D.

Answer - C.

To get the private and public IP addresses, you can run the following commands on the running instance.

http://169.254.169.254/latest/meta-data/local-ipv4 http://169.254.169.254/latest/meta-data/public-ipv4

Option A is partially correct, but it is an overhead when you already have the service running in AWS.

Option B is incorrect because CloudTrail is used for tracking the API activities of a resource.

Option D is incorrect because user-data cannot get the IP addresses.

For more information on instance metadata, please refer to the below URL-

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instancedata-data-retrieval.html

The correct option to identify the public and private IP addresses of new instances in an Auto Scaling group on AWS is C - Using a Curl or Get Command to get the latest meta-data from http://169.254.169.254/latest/meta-data/.

Explanation:

Amazon EC2 instances come with metadata that can be accessed by making a request to a special IP address - http://169.254.169.254/. This IP address is available to every EC2 instance, and it provides a way for the instance to learn about its own metadata regardless of the operating system or network configuration.

The metadata contains a wealth of information about the instance, including its instance ID, instance type, hostname, public and private IP addresses, security groups, and more. To access the metadata, you can use a command-line tool like Curl or a programming language like Python to make an HTTP request to the metadata endpoint.

To get the public and private IP addresses of a new instance in an Auto Scaling group, you can make an HTTP GET request to http://169.254.169.254/latest/meta-data/public-ipv4 and http://169.254.169.254/latest/meta-data/local-ipv4, respectively. These requests will return the instance's public and private IP addresses as plain text.

Option A is incorrect because Ipconfig and Ifconfig are commands to display network interface information on the local machine, not EC2 instances.

Option B is incorrect because CloudTrail is a service that logs AWS API calls and can be used for auditing and security purposes. It does not provide information about individual EC2 instances.

Option D is incorrect because user-data is information that can be passed to an instance when it is launched, typically in the form of a shell script or cloud-init script. It does not provide information about the instance's IP addresses.