An AWS certification question asks how you’d authenticate a mobile app. The answer is Web Identity Federation to login.
You then get a Secure Token from AWS STS and use an IAM policy.
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WIF.html
See also: https://docs.aws.amazon.com/cognito/latest/developerguide/what-is-amazon-cognito.html
Consolidated Billing is used to consolidate payments for multiple AWS accounts.
The master account:
https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/consolidated-billing.html
Newly created EBS volumes do not need any pre-warming and are available at peak performance from creation.
However volumes created from snapshots need to be pre-warmed using something like:
sudo dd if=/dev/xvdf of=/dev/null bs=1M
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-initialize.html