ACG Quiz 2 notes:

       You can change the instance tenancy attribute of a VPC from dedicated to default. Modifying the instance tenancy of the VPC does not affect the tenancy of any existing instances in the VPC. The next time you launch an instance in the VPC, it has a tenancy of default, unless you specify otherwise during launch. You can modify the instance tenancy attribute of a VPC using the AWS CLI, an AWS SDK, or the Amazon EC2 API only. Reference: Change the tenancy of a VPC.


       Amazon ElastiCache offers a fully managed Memcached and Redis service. Although the name only suggests caching functionality, the Redis service in particular can offer a number of operations such as Pub/Sub, Sorted Sets and an In-Memory Data Store. However, Amazon ElastiCache for Redis doesn't support multithreaded architectures.


       A file gateway supports a file interface into Amazon Simple Storage Service (Amazon S3) and combines a service and a virtual software appliance. By using this combination, you can store and retrieve objects in Amazon S3 using industry-standard file protocols such as Network File System (NFS) and Server Message Block (SMB). The software appliance, or gateway, is deployed into your on-premises environment as a virtual machine (VM) running on VMware ESXi, Microsoft Hyper-V, or Linux Kernel-based Virtual Machine (KVM) hypervisor. The gateway provides access to objects in S3 as files or file share mount points. You can manage your S3 data using lifecycle policies, cross-region replication, and versioning. You can think of a file gateway as a file system mount on S3. Reference: What is AWS Storage Gateway?.


Amazon SWF (not Amazon SQS) keeps track of all tasks and events in an application. Amazon SQS requires you to implement your own application-level tracking, especially if your application uses multiple queues. Amazon SWF FAQs.

To prevent other consumers from processing the message again, Amazon SQS sets a visibility timeout, a period of time during which Amazon SQS prevents other consumers from receiving and processing the message. The default visibility timeout for a message is 30 seconds. The minimum is 0 seconds. The maximum is 12 hours.


Reference: Instance store lifetime


Using the default settings metrics are sent every 5 minutes to CloudWatch. Using the detailed settings, metrics are then sent every 1 minute.