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Amazon Machine Images (AMIs) are the main building blocks of EC2. They allow you to configure an instance once (say, installing Apache or Nginx) and then create an image of that instance. The image can be used to launch more instances, all of which are functionally identical to the original. Of course, some attributes—such as the IP address or instance ID—must be unique, so there will be some differences.

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Cover of AWS System Administration

Note

1) Your CloudFormation template launches a two-tier web app. in us-east-1.

When you attempt to create a development stack in us-west-1, the process fails. What could be the problem?

A) The AMIs referenced in the template are not available in us-west-1. B) The IAM roles referenced in the template are not valid in us-west-1. C) Two ELB Classic Load Balancers cannot have the same Name tag. D) CloudFormation templates can be launched only in a single region.

ANSWER: A) AMIs are stored in a region and cannot be accessed in other regions. To use the AMI in another region, you must copy it to that region.

IAM roles are valid across the entire account.