SUMMARY

• AWS Storage Gateway Hardware Appliance is a physical hardware appliance which you use to connect your on-premises storage to AWS's storage and get virtually unlimited storage.

• General Purpose SSDs (gp2) is good for steady-state workloads and can burst up to 16,000 IOPS and you can boot off it.

• SQS short polling queries only a subset of the servers and provides an answer straight away.

• SQS long polling queries all of the servers and is when the when the wait time for the ReceiveMessageaction is greater than 0. It also provides cost savings by eliminating empty responses.

• ENA is an Elastic Network Adapter and provides enhanced networking for EC2 instances.

• EFA is an Elastic Fabric Adapter and is basically an ENA but with additional features like OS bypass but OS bypass does not work on Windows instances.

• ENI is an Elastic Network Interface is kind of like virtual network card for your VPCs.

• ParallelCluster is an open source management tool for managing HPC clusters.

• Auto Scaling Lifecycle Hooks are like breaks between instance state changes where you can perform custom actions. When you add more instances, it first goes into a Pending:Wait state where you can perform certain action before the EC2 instance has launched and then goes into a Pending:Proceed state when it launches. When you terminate instances, the same happens but instead with Terminating:Wait and Terminating:Proceed. The instance remains in the Wait state until you perform the CompleteLifecycleAction command.

• If you have an Aurora Replica, Aurora will change its CNAME to the Replica's CNAME and use that as the healthy one.

• If you have Aurora Serverless, it will automatically create a new database instance.

• If you don't have any of the above, Aurora will attempt to create a new database instance in the same availabilty zone on a best-effort basis.

• Redshift doesn't scale automatically and is normally for OLAP applications whereas Aurora can scale automatically and is general purpose.

• CloudFormation Outputs declares outputs for your stack.

• You can set up a Route53 Zone Apex with a Load Balancer by mapping your zone apex DNS name to your load balancer DNS name.

• In EBS, the following are encrypted:

  • The data moving to and from your instances to you EBS volumes.

  • The data inside the EBS volumes.

  • The snapshots created from the encrypted EBS volumes.

• The Systems Manager Run command lets you remotely and securely connect to managed EC2 instances to perform common admin tasks.

• Security Groups are stateful and NACLs are stateless, meaning that with Security Groups all return traffic is automatically allowed but with NACLs, you have to explicitly state if you want return traffic to be allowed and which return traffic.

• IAM roles and users are global entities.

• Amazon WorkSpaces is a managed Desktop as a Service solution - it allows you use desktops without managing a lot of the infrastructure you normally have to.

• You can use your EBS volumes like normal when snapshots are being created of that EBS volume.

• You can get logs (access logs) of your Elastic Load Balancers to see the connections.

• API Gateway has support for HTTPS endpoints and does not support HTTP (unencrypted).

• If you're trying to connect to your EC2 instance and you get a "server refused our key" error, there might be multiple reason why you got this, some could include:

  • The username you are using is wrong.

  • You don't have permissions for the file or directory.

  • The user you're tying to login as has been deleted.