AWS Certified Foundational CLF-C02 Syllabus Exam Questions Answers

Spot Instances are a type of EC2 instance that let you bid on unused compute capacity, which AWS offers at a discount of up to 90% compared to On-Demand prices1. Spot Instances are suitable for fault-tolerant, stateless, or flexible applications that can handle interruptions2. Spot Instances can be interrupted with a two-minute warning when EC2 needs the capacity back3. The other options are not pricing models that will interrupt a running EC2 instance if capacity becomes temporarily unavailable

The approach that will achieve the goal of designing a reliable web application that is hosted on Amazon EC2 is to spread EC2 instances across more than one Availability Zone. An Availability Zone is a physically isolated location within an AWS Region that has its own power, cooling, and network connectivity. By spreading EC2 instances across multiple Availability Zones, users can increase the fault tolerance and availability of their web applications, as well as reduce latency for end users2. Launching large EC2 instances in the same Availability Zone, spreading EC2 instances across more than one security group, or using an Amazon Machine Image (AMI) from AWS Marketplace are not sufficient to ensure reliability, as they do not provide redundancy or resilience in case of an outage in one Availability Zone.

AWS Network Firewall is a managed service that makes it easy to deploy essential network protections for all of your Amazon Virtual Private Clouds (VPCs). The service can be set up with just a few clicks from the AWS console or using APIs. AWS Network Firewall automatically scales with your network traffic, so you don’t have to worry about deploying and managing any infrastructure. AWS Network Firewall provides protection from common network threats such as SQL injection, cross-site scripting, and DDoS attacks1.

Amazon EC2 instance store provides temporary block-level storage for your EC2 instance. This storage is located on disks that are physically attached to the host computer. Instance store is ideal for temporary storage of information that changes frequently, such as buffers, caches, scratch data, and other temporary content. It can also be used to store temporary data that you replicate across a fleet of instances, such as a load-balanced pool of web servers. An instance store consists of one or more instance store volumes exposed as block devices. The size of an instance store as well as the number of devices available varies by instance type and instance size. The virtual devices for instance store volumes are ephemeral[0-23]. Instance types that support one instance store volume have ephemeral0. Instance types that support two or more instance store volumes have ephemeral0, ephemeral1, and so on. Instance store pricing Instance store volumes are included as part of the instance’s usage cost. The data on an instance store volume persists even if the instance is rebooted. However, the data does not persist if the instance is stopped, hibernated, or terminated. When the instance is stopped, hibernated, or terminated, every block of the instance store volume is cryptographically erased. Therefore, do not rely on instance store volumes for valuable, long-term data. If you need to retain the data stored on an instance store volume beyond the lifetime of the instance, you need to manually copy that data to more persistent storage, such as an Amazon EBS volume, an Amazon S3 bucket, or an Amazon EFS file system. There are some events that can result in your data not persisting throughout the lifetime of the instance. The following table indicates whether data on instance store volumes is persisted during specific events, for both virtualized and bare metal instances1. References: Amazon EC2 instance store - Amazon Elastic Compute Cloud