--- tags: - cloud - l1 - flashcard-deck - aws-compute --- [Portal](../../../../library/portal/index.md) | **Level:** [L1: Foundations](../../../../library/portal/levels.md) | **Topics:** [AWS EC2](../../../../library/portal/topics.md) | **Domain:** Cloud id category difficulty tags question answer source_path aws-compute/034c74d36723 aws-compute medium aws, ec2, reserved-instances Explain EC2 Capacity Reservations * Allows you to ensure you have EC2 capacity when you need it\n* Usually combined with Reserved Instances and Saving Plans to achieve cost saving\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/089-explain-ec2-capacity-reservations.txt aws-compute/044c930ced78 aws-compute easy aws, ec2, ecs What is Amazon ECS and how does it orchestrate containers? "[AWS Docs](https://aws.amazon.com/ecs): ""Amazon Elastic Container Service (Amazon ECS) is a fully managed container orchestration service. Customers such as Duolingo, Samsung, GE, and Cook Pad use ECS to run their most sensitive and mission critical applications because of its security, reliability, and scalability.""\n\nIn simpler words, it allows you to launch containers on AWS. \nWhile AWS takes care of starting/stopping containers, you need to provision and maintain the infrastructure where the containers are running (EC2 instances).\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances." projects/knowledge/interview/aws/131-what-is-amazon-ecs.txt aws-compute/0b833d7fe5ba aws-compute medium aws, ec2 Explain EC2 Instance Store. Why would someone choose to use it over other options? EC2 instance store provides better I/O performances when compared to EBS. \nIt is mostly used for cache and temporary data purposes.\n\nGotcha: instance store data is lost when the instance stops, terminates, or hibernates — physically attached to the host. Use EBS for persistence.\n\nUnder the hood: instance store uses NVMe SSDs on the hypervisor host, delivering hundreds of thousands of IOPS with sub-millisecond latency.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/046-explain-ec2-instance-store-why-would-someone-choos.txt aws-compute/0cbc97065ff9 aws-compute medium aws, auto-scaling What is Warmup and Cool down period ? * *Warm Up Time*: Duration for newly launched instances to stabilize before they receive full traffic.\n* *Cool Down Period*: Time during which Auto Scaling waits before another scaling activity.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/451-what-is-warmup-and-cool-down-period.txt aws-compute/0d8c4a5bdd5e aws-compute medium aws, auto-scaling, ec2 Explain Auto Scaling Group "[Amazon Docs](https://docs.aws.amazon.com/autoscaling/ec2/userguide/AutoScalingGroup.html): ""An Auto Scaling group contains a collection of Amazon EC2 instances that are treated as a logical grouping for the purposes of automatic scaling and management. An Auto Scaling group also enables you to use Amazon EC2 Auto Scaling features such as health check replacements and scaling policies""\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max." projects/knowledge/interview/aws/202-explain-auto-scaling-group.txt aws-compute/12464c809875 aws-compute medium aws, ec2 If you would like to have an hardware disk attached to your EC2 instead of a network one (EBS). What would you use? EC2 Instance Store.\n\nGotcha: instance store data is lost when the instance stops, terminates, or hibernates — physically attached to the host. Use EBS for persistence.\n\nUnder the hood: instance store uses NVMe SSDs on the hypervisor host, delivering hundreds of thousands of IOPS with sub-millisecond latency.\n\nRemember: EBS volume types: gp3 (general purpose, baseline 3000 IOPS), io2 (high IOPS, up to 64000), st1 (throughput HDD), sc1 (cold HDD). gp3 is the default choice for most workloads. projects/knowledge/interview/aws/045-if-you-would-like-to-have-an-hardware-disk-attache.txt aws-compute/1b0cb8ccb7e4 aws-compute medium aws, ami, ec2, ecs What one should do in order to make EC2 instance part of an ECS cluster? Install ECS agent on it. Some AMIs have built-in configuration for that.\n\nUnder the hood: the ECS agent is a Go binary that registers the instance with the ECS control plane, pulls images, and manages task lifecycle.\n\nGotcha: Amazon Linux 2/2023 AMIs include the ECS agent. Other AMIs require manual install and configuration.\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances. projects/knowledge/interview/aws/132-what-one-should-do-in-order-to-make-ec2-instance-p.txt aws-compute/1c9b1748c070 aws-compute hard aws, spot-instances True or False? Cancelling a Spot instance request terminates the instance False. When you cancel a Spot instance request, you are not terminating the instances created by it. \nTo terminate such instances, you must cancel the Spot instance request first.\n\nRemember: Spot = up to 90% cheaper but can be reclaimed with 2-minute warning. Great for batch jobs, CI/CD runners, and stateless workers.\n\nGotcha: spot instances get a 2-minute termination notice via instance metadata. Your app must handle graceful shutdown. projects/knowledge/interview/aws/079-true-or-false-cancelling-a-spot-instance-request-t.txt aws-compute/20500b9163cb aws-compute easy aws, ec2 What is AWS EC2 and when would you use it? a web service that provides secure, resizable compute capacity in the cloud.\nRead more [here](https://aws.amazon.com/ec2)\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because capacity scales in minutes, not weeks.\n\nFun fact: EC2 launched August 2006 with one instance type (m1.small, 1.7GB RAM). Today there are 750+ types.\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because you can scale up/down on demand.\n\nRemember: EC2 instance types follow the pattern: family + generation + size. Example: m5.xlarge = general purpose, 5th gen, extra large. projects/knowledge/interview/aws/020-what-is-ec2.txt aws-compute/2158de78b0b9 aws-compute medium aws, ec2, reserved-instances Which tool would you use for choosing between Reserved instances or On-Demand instances? AWS Cost Explorer — a built-in console tool that analyzes your historical spending patterns and usage data, then provides recommendations on whether Reserved Instances or Savings Plans would reduce costs compared to On-Demand pricing.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/271-which-tool-would-you-use-for-choosing-between-rese.txt aws-compute/22b926c404c6 aws-compute medium aws, ami, ec2 What would you use for customizing EC2 instances? As in software installation, OS configuration, etc. AMI. With AMI (Amazon Machine Image) you can customize EC2 instances by specifying which software to install, what OS changes should be applied, etc.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/023-what-would-you-use-for-customizing-ec2-instances-a.txt aws-compute/260ea55770ea aws-compute hard aws, ec2, spot-instances What are Spot Fleets? Set of Spot instances and if you would like, also on-demand instances.\n\nUnder the hood: Spot Fleet maintains target capacity by automatically replacing interrupted instances from your specified launch specs.\n\nGotcha: diversify across multiple instance types and AZs to reduce interruption probability.\n\nRemember: Spot = up to 90% cheaper but can be reclaimed with 2-minute warning. Great for batch jobs, CI/CD runners, and stateless workers.\n\nGotcha: spot instances get a 2-minute termination notice via instance metadata. Your app must handle graceful shutdown. projects/knowledge/interview/aws/080-what-are-spot-fleets.txt aws-compute/26c964dec8e0 aws-compute hard aws, ec2, reserved-instances You need an instance for two years, but only between 10:00-15:00 every day. Which pricing model would you use? "Reserved instances from the ""Scheduled Reserved Instances"" type which allows you to reserve for specific time window (like 10:00-15:00 every day).\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/063-you-need-an-instance-for-two-years-but-only-betwee.txt aws-compute/288d1d911ae3 aws-compute easy aws, elastic-beanstalk What is AWS Elastic Beanstalk? "AWS definition: ""AWS Elastic Beanstalk is an easy-to-use service for deploying and scaling web applications and services...You can simply upload your code and Elastic Beanstalk automatically handles the deployment""\n\nLearn more about it [here](https://aws.amazon.com/elasticbeanstalk)\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/370-what-is-aws-elastic-beanstalk.txt aws-compute/2b68f966c694 aws-compute hard aws, placement-groups "What are the cons and pros of the ""Spread"" placement group strategy?" Cons:\n * Current limitation is 7 instances per AZ (per replacement group)\nPros:\n * Maximized high availability (instances on different hardware, span across AZs)\n\nRemember: Cluster = low latency (same rack). Spread = high availability (different racks). Partition = large distributed workloads (separate failure domains). projects/knowledge/interview/aws/100-what-are-the-cons-and-pros-of-the-spread-placement.txt aws-compute/2e11972eec83 aws-compute easy aws, ec2 Explain what is EC2 Nitro * Next generation EC2 instances using new virtualization technology\n* Better EBS: 64,000 EBS IOPS\n* Better networking: HPC, IPv6\n* Better security\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because you can scale up/down on demand.\n\nRemember: EC2 instance types follow the pattern: family + generation + size. Example: m5.xlarge = general purpose, 5th gen, extra large. projects/knowledge/interview/aws/087-explain-what-is-ec2-nitro.txt aws-compute/2ffa0898a251 aws-compute hard aws, spot-instances What strategies are there to allocate Spot instances? * lowestPrice: launch instances from the pool that has the lowest price\n* diversified: distributed across all pools\n* capacityOptimized: optimized based on the number of instances\n\nRemember: Spot = up to 90% cheaper but can be reclaimed with 2-minute warning. Great for batch jobs, CI/CD runners, and stateless workers.\n\nGotcha: spot instances get a 2-minute termination notice via instance metadata. Your app must handle graceful shutdown. projects/knowledge/interview/aws/081-what-strategies-are-there-to-allocate-spot-instanc.txt aws-compute/35d48ada25d6 aws-compute hard aws, ecs, fargate You need a persistent shared storage between your containers that some are running in Fargate and some in ECS. What would you use? EFS. It allows us to have persistent multi-AZ shared storage for containers.\n\nUnder the hood: EFS is managed NFS v4.1 — auto-scaling, per-GB billing, no pre-provisioning. Mount targets needed in each AZ.\n\nGotcha: EFS burst throughput is very low for small filesystems (50KB/s per GB stored). Use provisioned throughput for production.\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances. projects/knowledge/interview/aws/395-you-need-a-persistent-shared-storage-between-your-.txt aws-compute/36a6654bdb71 aws-compute medium aws, reserved-instances True or False? Reserved instance has to be used for a minimum of 1 year True. AWS Reserved Instances require a minimum 1-year commitment (1-year or 3-year terms) in exchange for significant discounts over On-Demand pricing.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/057-true-or-false-reserved-instance-has-to-be-used-for.txt aws-compute/37dc5e671f55 aws-compute hard aws, ec2, ecs, fargate How AWS Fargate different from AWS ECS? In AWS ECS, you manage the infrastructure - you need to provision and configure the EC2 instances. \nWhile in AWS Fargate, you don't provision or manage the infrastructure, you simply focus on launching Docker containers. You can think of it as the serverless version of AWS ECS.\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances. projects/knowledge/interview/aws/138-how-aws-fargate-different-from-aws-ecs.txt aws-compute/37e6a4ac0469 aws-compute medium aws, ec2 what are launch configuration and launch template and how do they differ from each other. Both are like instructions for creating computers (EC2 instances), but a launch configuration is an older set of rules, while a launch template is a newer, more flexible, and organized way of doing the same job but Launch Templates offer more features and flexibility compared to Launch Configurations.\n\nRemember: launch templates replace launch configurations. They support versioning, can be updated, and work with ASG, EC2 Fleet, and Spot Fleet. projects/knowledge/interview/aws/410-what-are-launch-configuration-and-launch-template-.txt aws-compute/3d723ca95ab2 aws-compute medium aws, lambda What AWS services are serverless (or have the option to be serverless)? AWS Lambda\nAWS Athena\n\nRemember: EC2 instance naming: family (m=general, c=compute, r=memory, t=burstable) + generation + size. Example: m6i.xlarge = 6th gen Intel general purpose.\n\nGotcha: always use the latest generation for better price-performance. m6i is cheaper AND faster than m5. projects/knowledge/interview/aws/381-what-aws-services-are-serverless-or-have-the-optio.txt aws-compute/45ecf029ce3d aws-compute hard aws, ec2 You need a physical server only for your use. Which pricing model are you going to use? EC2 Dedicated Host\n\nUnder the hood: Dedicated Hosts give socket and core visibility for license compliance (per-core Oracle, Windows Server, SQL Server).\n\nGotcha: most expensive EC2 option. Use Dedicated Instances if you only need hardware isolation without socket/core visibility.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/065-you-need-a-physical-server-only-for-your-use-which.txt aws-compute/573ccd9aa325 aws-compute hard aws, auto-scaling True or False? by default, ASG tries to balance the number of instances across AZ True, this is why when it terminates instances, it chooses the AZ with the most instances.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/210-true-or-false-by-default-asg-tries-to-balance-the-.txt aws-compute/59f1670758e9 aws-compute hard aws, auto-scaling, ec2 What can you tell me about warm pool ? A feature in EC2 Auto Scaling Groups that allows pre-provisioning instances to respond to sudden traffic spikes.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/457-what-can-you-tell-me-about-warm-pool.txt aws-compute/5dde862751b8 aws-compute medium aws, ec2 True or False? Region is a factor when it comes to EC2 costs/pricing True. You pay differently based on the chosen region.\n\nExample: m5.large costs ~$0.096/hr in us-east-1 but ~$0.112/hr in eu-west-1 — 17% more due to local power, real estate, and tax costs.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/353-true-or-false-region-is-a-factor-when-it-comes-to-.txt aws-compute/5e6bb5bb8d2e aws-compute medium aws, ami, image-builder, packer How have you handled golden images? I've worked with AWS Image Builder and Packer-style pipelines to generate pre-hardened AMIs. The workflow is usually: baseline OS → apply security hardening → install required packages → run validation tests → push to AMI catalog. This keeps patching consistent and eliminates drift.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/462-how-have-you-handled-golden-images.txt aws-compute/6032d58d977c aws-compute hard aws, auto-scaling Describe one way to test ASG actually works In Linux instances, you can install the 'stress' package and run stress to load the system for certain period of time and see if ASG kicks in by adding additional capacity (= more instances).\n\nFor example: `sudo stress --cpu 100 --timeout 20`\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/213-describe-one-way-to-test-asg-actually-works.txt aws-compute/6116cf8104f5 aws-compute medium aws, ami True or False? AMI are built for specific region True (but they can be copied from one region to another).\n\nUnder the hood: AMIs are stored in S3 within a region. Cross-region copies create a new AMI ID and can take minutes to hours depending on size.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/026-true-or-false-ami-are-built-for-specific-region.txt aws-compute/617adb77f83b aws-compute hard aws, auto-scaling Explain scaling cooldowns in regards to Auto Scaling Groups During a scaling cooldown, ASG will not terminate or launch additional instances. The cooldown happens after scaling activity and the reason for this behaviour is that some metrics have to be collected and stabilize before another scaling operating can take place.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/208-explain-scaling-cooldowns-in-regards-to-auto-scali.txt aws-compute/6474e2450ba1 aws-compute medium aws, ec2 From networking perspective, what do you get by default when running an EC2 instance? A private IP and a public IP.\n\nGotcha: the public IP changes on stop/start. Use an Elastic IP (EIP) for a static public address that persists.\n\nUnder the hood: the public IP is invisible inside the instance (ip addr shows only private IP). AWS NATs at the Internet Gateway.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/082-from-networking-perspective-what-do-you-get-by-def.txt aws-compute/6592099263ff aws-compute hard aws, ec2 What happens to the EC2 disk (EBS) when the instance is stopped? Disk is intact and can be used when the instance starts.\n\nGotcha: applies to EBS-backed instances only. Instance store volumes are wiped on stop. You still pay for the EBS volume while the instance is stopped.\n\nRemember: EBS volume types: gp3 (general purpose, baseline 3000 IOPS), io2 (high IOPS, up to 64000), st1 (throughput HDD), sc1 (cold HDD). gp3 is the default choice for most workloads. projects/knowledge/interview/aws/034-what-happens-to-the-ec2-disk-ebs-when-the-instance.txt aws-compute/67b404740332 aws-compute medium aws, auto-scaling If you use ASG and you would like to run extra steps before the instance goes in service, what will you use? Lifecycle hooks in pending state.\n\nUnder the hood: hooks pause the instance in Pending:Wait, allowing scripts (via SNS/SQS) for config pulls, service registration, or smoke tests before joining the load balancer.\n\nGotcha: if the hook does not send CONTINUE within the timeout (default 3600s), the instance is terminated or abandoned.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/212-if-you-use-asg-and-you-would-like-to-run-extra-ste.txt aws-compute/68602c9049cd aws-compute hard aws, ec2 What's the difference between Restart and Start/Stop of an ec2-instance ? Restart: Quickly halts and restarts the instance.\nStart/Stop: Completely halts the instance, which persists even after a start command. The VM is launched on a different host machine.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/459-whats-the-difference-between-restart-and-startstop.txt aws-compute/69c71fb1229f aws-compute easy aws, lambda, serverless What is AWS Lambda and when would you use serverless compute? AWS Lambda is a serverless compute service that runs your code in response to events (e.g., HTTP requests, file uploads) without you provisioning or managing servers. You upload your function code, and Lambda handles executing it on-demand and scaling automatically.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/470-what-is-lambda.txt aws-compute/6c03444f8965 aws-compute medium aws, ec2 True or False? The following are instance types available for a user in AWS: False. From the above list only compute optimized is available.\n\nRemember: EC2 families — General (M/T), Compute (C), Memory (R/X), Storage (I/D), Accelerated (P/G/Inf). Mnemonic: 'Many Tasks Compute, Requiring eXtra IO, Delivering Parallel GPU work.'\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/030-true-or-false-the-following-are-instance-types-ava.txt aws-compute/6d1efeb8e2a8 aws-compute medium aws, ecs, lambda Explain the difference between AWS ECS and AWS EKS. * ECS (Elastic Container Service): It's a container management service for Docker containers, offering simplicity and native integration with other AWS services. \n* EKS (Elastic Kubernetes Service): It's a managed Kubernetes service offering open-source flexibility and scalability with less AWS-specific functionality.\n\nRemember: EKS = managed Kubernetes control plane. AWS handles etcd, API server, scheduler. You manage worker nodes (or use Fargate for serverless pods). projects/knowledge/interview/aws/430-explain-the-difference-between-aws-ecs-and-aws-eks.txt aws-compute/723e49488011 aws-compute medium aws, ec2 What bootstrapping means and how to use it in AWS EC2? Bootstrapping is about launching commands when a machine starts for the first time.\nIn AWS EC2 this is done using the EC2 user data script.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/075-what-bootstrapping-means-and-how-to-use-it-in-aws-.txt aws-compute/7cbb0c17ef5b aws-compute easy aws, compute "What is an ""EC2 Instance""?" A virtual server running in the cloud.\n\nUnder the hood: EC2 runs on the Nitro hypervisor (since 2017), which offloads networking, storage, and security to dedicated hardware for near-bare-metal performance.\n\nFun fact: the smallest current type (t4g.nano) has 2 vCPUs, 0.5GB RAM, and costs ~$3/month.\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because you can scale up/down on demand.\n\nRemember: EC2 instance types follow the pattern: family + generation + size. Example: m5.xlarge = general purpose, 5th gen, extra large. projects/knowledge/interview/aws/464-ec2-instance.txt aws-compute/81ff7f4588cd aws-compute easy aws, sqs What is Simple Queue Service (SQS)? "AWS definition: ""Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications"".\n\nLearn more about it [here](https://aws.amazon.com/sqs)\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/329-what-is-simple-queue-service-sqs.txt aws-compute/832296051843 aws-compute medium aws, lightsail Which service would you use for building a website or web application? Amazon Lightsail. It bundles a VPS with compute, storage, DNS, and a static IP into a single low-cost plan — ideal for simple sites without full EC2 complexity.\n\nRemember: EBS volume types: gp3 (general purpose, baseline 3000 IOPS), io2 (high IOPS, up to 64000), st1 (throughput HDD), sc1 (cold HDD). gp3 is the default choice for most workloads. projects/knowledge/interview/aws/270-which-service-would-you-use-for-building-a-website.txt aws-compute/85fb7c927eb6 aws-compute medium aws, ec2, spot-instances Which pricing model has potentially the biggest discount and what its advantage Spot instances provide the biggest discount but has the disadvantage of risking losing them due bigger bid price.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/062-which-pricing-model-has-potentially-the-biggest-di.txt aws-compute/87305789c940 aws-compute hard aws, placement-groups "What are the cons and pros of the ""Cluster"" placement group strategy?" Cons: if the hardware fails, all instances fail\nPros: Low latency & high throughput network\n\nRemember: Cluster = low latency (same rack). Spread = high availability (different racks). Partition = large distributed workloads (separate failure domains). projects/knowledge/interview/aws/099-what-are-the-cons-and-pros-of-the-cluster-placemen.txt aws-compute/87373110fb82 aws-compute medium aws, elastic-beanstalk Explain the benefits of using AWS Elastic Beanstalk. Elastic Beanstalk: It's a service that simplifies deployment and management of applications in the AWS cloud. \nBenefits: It streamlines infrastructure management, eases deployment, and allows developers to focus on coding. projects/knowledge/interview/aws/444-explain-the-benefits-of-using-aws-elastic-beanstal.txt\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. aws-compute/87f23ed6f2d4 aws-compute medium aws, lambda You would like to invoke a function every time you enter a URL in the browser. Which service would you use for that? AWS Lambda. It runs code in response to events (including API Gateway HTTP triggers) with no servers to manage. You pay only for execution time.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/267-you-would-like-to-invoke-a-function-every-time-you.txt aws-compute/8a6b7f739294 aws-compute easy aws, ec2, ecr, spot-instances What is the difference between Launch Configuration and Launch Template? Launch configuration is a legacy form of Launch Template that must be recreated every time you would like to update the configuration.\n\nIn addition, launch template has the clear benefits of:\n * Provision both On-Demand and Spot instances\n * supporting multiple versions\n * support creating parameters subsets (used for reuse and inheritance)\n\nRemember: launch templates replace launch configurations. They support versioning, can be updated, and work with ASG, EC2 Fleet, and Spot Fleet. projects/knowledge/interview/aws/091-what-is-the-difference-between-launch-configuratio.txt aws-compute/8c80e3c86f5a aws-compute medium aws, ec2 You need an instance for short-term and the workload running on instance must not be interrupted. Which pricing model would you use? On Demand is good for short-term non-interrupted workloads (but it also has the highest cost).\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/060-you-need-an-instance-for-short-term-and-the-worklo.txt aws-compute/8dba10449038 aws-compute medium aws, ec2 What are some of the differences between dedicated hosts and dedicated instances? In dedicated hosts you have per host billing, you have more visibility (sockets, cores, ...) and you can control where instance will be placed. \nIn dedicated instances the billing is per instance but you can't control placement and you don't have visibility of sockets, cores, ...\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/066-what-are-some-of-the-differences-between-dedicated.txt aws-compute/8f47d6728236 aws-compute medium aws, ec2 True or False? Using EC2 hibernate option results in having faster instance boot True. This is because the operating system isn't restarted or stopped.\n\nRemember: EC2 instance naming: family (m=general, c=compute, r=memory, t=burstable) + generation + size. Example: m6i.xlarge = 6th gen Intel general purpose.\n\nGotcha: always use the latest generation for better price-performance. m6i is cheaper AND faster than m5. projects/knowledge/interview/aws/084-true-or-false-using-ec2-hibernate-option-results-i.txt aws-compute/93b007c3aa04 aws-compute medium aws, ami, ec2 What is an AMI in context with Ec2 instance ? Think of an AMI as a pre-set computer setup you can use to create new computers (EC2 instances). It's like a special recipe for a computer, including the operating system, software, and settings. It can be referred as an Image ISO of the operating system to be installed, It's a pre-configured template used to create EC2 instances. It includes the operating system, application server, and applications.\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because you can scale up/down on demand.\n\nRemember: EC2 instance types follow the pattern: family + generation + size. Example: m5.xlarge = general purpose, 5th gen, extra large. projects/knowledge/interview/aws/406-what-is-an-ami-in-context-with-ec2-instance.txt aws-compute/940df1918ac3 aws-compute easy aws, ec2, compute What is Amazon EC2 used for? Amazon Elastic Compute Cloud (EC2) provides scalable virtual servers in the cloud (compute instances) that you can launch on-demand to run applications. Essentially, EC2 offers resizable compute capacity (VMs) in AWS.\n\nName origin: EC2 = Elastic Compute Cloud. 'Elastic' because you can scale up/down on demand.\n\nRemember: EC2 instance types follow the pattern: family + generation + size. Example: m5.xlarge = general purpose, 5th gen, extra large. projects/knowledge/interview/aws/464-what-is-ec2.txt aws-compute/99cdaeb44d42 aws-compute hard aws, auto-scaling, ec2 Explain the default ASG termination policy 1. It finds the AZ which the most number of EC2 instances\n2. If number of instances > 1, choose the one with oldest launch configuration, template and terminate it\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/209-explain-the-default-asg-termination-policy.txt aws-compute/a2627391f9a0 aws-compute medium aws, ec2, ecs, fargate What ECS launch types are there? * EC2 Instance\n* AWS Fargate\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances. projects/knowledge/interview/aws/133-what-ecs-launch-types-are-there.txt aws-compute/a53fce9dbfbe aws-compute medium aws, ec2 True or False? In EC2 On Demand, you pay per hour when using Linux or Windows and per second (after first minute) when using any other operating system False. You pay per second (after the first minute) when using Windows or Linux and per hour for any other OS.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/059-true-or-false-in-ec2-on-demand-you-pay-per-hour-wh.txt aws-compute/ad2fa7c63e81 aws-compute medium aws, auto-scaling Explain Lifecycle hooks in regards to Auto Scaling Groups Lifecycle hooks allows you perform extra steps before the instance goes in service (During pending state) or before it terminates (during terminating state).\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/211-explain-lifecycle-hooks-in-regards-to-auto-scaling.txt aws-compute/ad8ae703dff4 aws-compute medium aws, ami, ec2 Explain the instance type naming convention Let's take for example the following instance type: m5.large\n\n`m` is the instance class\n`5` is the generation\n`large` is the size of the instance (affects the spec properties like vCPUs and RAM)\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/029-explain-the-instance-type-naming-convention.txt aws-compute/ae4af8a2b32a aws-compute medium aws, ami What are the different sources for AMIs? * Personal AMIs - AMIs you create\n* AWS Marketplace for AMIs - AMIs made by others, mostly sold for some price\n* Public AMIs - Provided by AWS\n\nRemember: AMI = Amazon Machine Image. It's a snapshot of an EC2 instance: OS, software, config. Think 'golden image.' projects/knowledge/interview/aws/025-what-are-the-different-sources-for-amis.txt aws-compute/b00aef197ec7 aws-compute medium aws, ami, ec2, lambda Explain the difference between EC2 and Lambda in AWS.\nExpected **Answer:** EC2 provides virtual servers that you manage, while Lambda allows serverless execution of code without server provisioning. EC2 Instance: It's a virtual server in the cloud where you can run applications. Think of it as a computer system hosted in AWS.\nAMI (Amazon Machine Image): It's a template that provides the information needed to launch an EC2 instance. An AMI includes the operating system, application server, and applications. While an EC2 instance is like a running computer, an AMI is like a blueprint or image of that computer.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/420-explain-the-difference-between-ec2-and-lambda-in-a.txt aws-compute/b023adfc51b0 aws-compute easy aws, auto-scaling What is a predictive scaling policy in regards to Auto Scaling Groups? Scale by analyzing historical load and schedule scaling based on forecast load.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/207-what-is-a-predictive-scaling-policy-in-regards-to-.txt aws-compute/b066a1a3b3d0 aws-compute medium aws, ec2 What CPU customization is available with EC2? * Modifying number of CPU cores (useful for high RAM and low CPU applications)\n* Modifying number of threads per cure (useful for HPC workloads)\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/088-what-cpu-customization-is-available-with-ec2.txt aws-compute/b17d4d91905c aws-compute medium aws, lambda What is AWS Lambda Layers? Lambda Layers: These allow you to centrally manage common code and data shared across multiple Lambda functions. Layers are useful for shared libraries, custom runtimes, and dependencies.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/431-what-is-aws-lambda-layers.txt aws-compute/b4b38fc853b0 aws-compute easy aws, lightsail What is AWS Lightsail? "AWS definition: ""Lightsail is an easy-to-use cloud platform that offers you everything needed to build an application or website, plus a cost-effective, monthly plan.""\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/360-what-is-aws-lightsail.txt aws-compute/b4ff24904978 aws-compute easy aws, ecr What is Amazon ECR (Elastic Container Registry)? "[AWS Docs](https://aws.amazon.com/ecr): ""Amazon Elastic Container Registry (ECR) is a fully-managed Docker container registry that makes it easy for developers to store, manage, and deploy Docker container images.""\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/134-what-is-amazon-ecr.txt aws-compute/b565a433d283 aws-compute medium aws, ec2, reserved-instances, spot-instances What EC2 pricing models are there? On Demand - pay a fixed rate by the hour/second with no commitment. You can provision and terminate it at any given time.\nReserved - you get capacity reservation, basically purchase an instance for a fixed time of period. The longer, the cheaper.\nSpot - Enables you to bid whatever price you want for instances or pay the spot price.\nDedicated Hosts - physical EC2 server dedicated for your use.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/056-what-ec2-pricing-models-are-there.txt aws-compute/b7356f918548 aws-compute medium aws, ec2, spot-instances, cost-optimization What are Spot Instances in AWS EC2? Spot Instances are spare EC2 capacity offered at up to 90% discount in exchange for the caveat that AWS can reclaim (terminate) them with a 2-minute notice if needed. They are great for fault-tolerant, flexible workloads that can handle interruptions.\n\nRemember: Spot = up to 90% cheaper but can be reclaimed with 2-minute warning. Great for batch jobs, CI/CD runners, and stateless workers.\n\nGotcha: spot instances get a 2-minute termination notice via instance metadata. Your app must handle graceful shutdown. projects/knowledge/interview/aws/476-what-are-spot-instances.txt aws-compute/ba77a8e5c8a2 aws-compute easy aws, lambda Explain what is AWS Lambda "AWS definition: ""AWS Lambda lets you run code without provisioning or managing servers. You pay only for the compute time you consume.""\n\nRead more on it [here](https://aws.amazon.com/lambda)\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage." projects/knowledge/interview/aws/125-explain-what-is-aws-lambda.txt aws-compute/bcfc92f3b2d9 aws-compute medium aws, ec2 Can you tell me bunch of ec2 instance types ? EC2 instances come in various sizes and capabilities, just like different cars have different features. There are types for general tasks, memory-intensive work, or high-performance computing, each suited for specific jobs. Some of these would be t2, t3, m4, m5, c5 etc.\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/405-can-you-tell-me-bunch-of-ec2-instance-types.txt aws-compute/bd1e0338d849 aws-compute medium aws, ec2, reserved-instances You need an instance for running an application for a period of 2 years continuously, without changing instance type. Which pricing model would you use? Reserved instances: they are cheaper than on-demand and the instance is yours for the chosen period of time.\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/061-you-need-an-instance-for-running-an-application-fo.txt aws-compute/bd3e2e490614 aws-compute hard aws, lambda What are different frameworks of Lambda, why do we even require them ? Lambda is like a team of workers you can hire to do specific jobs whenever you need. Frameworks give these workers different skills for various tasks, allowing them to handle different types of jobs efficiently. Examples include Serverless Framework, SAM (Serverless Application Model), and Chalice. They streamline Lambda deployments.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/409-what-are-different-frameworks-of-lambda-why-do-we-.txt aws-compute/bda25db7b23a aws-compute medium aws, lambda Describe AWS Lambda and its use cases. AWS Lambda: It's a serverless computing service that runs code in response to events and automatically manages resources. It's ideal for executing small, event-driven functions, making it perfect for tasks like data processing, file handling, and automation.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/423-describe-aws-lambda-and-its-use-cases.txt aws-compute/c24cc8c2fb2e aws-compute easy aws, ec2 What is the AWS Instance Connect? "[AWS](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Connect-using-EC2-Instance-Connect.html): ""Amazon EC2 Instance Connect provides a simple and secure way to connect to your Linux instances using Secure Shell (SSH).""\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/077-what-is-the-aws-instance-connect.txt aws-compute/c26fbe9b3f4a aws-compute medium aws, ec2, reserved-instances Explain the following types of reserved instances: * Convertible Reserved Instances: used for long running workloads but used when instance type might change during the period of time it's reserved\n* Scheduled Reserved Instances: when you need to reserve an instance for a long period but you don't need it continuously (so for example you need it only in the morning)\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/058-explain-the-following-types-of-reserved-instances-.txt aws-compute/c5a951302e8a aws-compute easy aws, ecs, fargate What is AWS Fargate and how does it run containers without managing servers? "[Amazon Docs](https://aws.amazon.com/fargate): ""AWS Fargate is a serverless, pay-as-you-go compute engine that lets you focus on building applications without managing servers. AWS Fargate is compatible with both Amazon Elastic Container Service (ECS) and Amazon Elastic Kubernetes Service (EKS)""\n\nIn simpler words, AWS Fargate allows you launch containers on AWS without worrying about managing infrastructure. It runs containers based on the CPU and RAM you need.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective." projects/knowledge/interview/aws/137-what-is-aws-fargate.txt aws-compute/c5fb058d120b aws-compute easy aws, ec2 What is a launch template? "[AWS Docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-launch-templates.html): ""You can create a launch template that contains the configuration information to launch an instance. You can use launch templates to store launch parameters so that you do not have to specify them every time you launch an instance""\n\nRemember: launch templates replace launch configurations. They support versioning, can be updated, and work with ASG, EC2 Fleet, and Spot Fleet." projects/knowledge/interview/aws/090-what-is-a-launch-template.txt aws-compute/c7d290c8b9bd aws-compute hard aws, serverless What is the maximum execution time for a Lambda function? 15 minutes (900 seconds). This is the maximum execution timeout for a single AWS Lambda invocation. For longer-running workloads, consider Step Functions, ECS/Fargate tasks, or breaking the work into chained Lambda calls.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/469-lambda-max-time.txt aws-compute/c984822a27bf aws-compute hard aws, ecs, fargate How to share data between containers (some from ECS and some from Fargate)? Using EFS is a good way to share data between containers and it works also between different AZs.\n\nRemember: ECS = AWS-native container orchestration. Fargate = serverless ECS (no EC2 to manage). EC2 launch type = you manage the instances. projects/knowledge/interview/aws/136-how-to-share-data-between-containers-some-from-ecs.txt aws-compute/cb1c34557079 aws-compute medium aws, ami, ec2 Explain each of the following instance types: Compute Optimized:\n\n* Used for compute-intensive tasks\n* It has high performance processors\n* Use cases vary: gaming serves, machine learning, batch processing, etc.\n\nMemory Optimized:\n\n* Used for processing large data sets in memory\n* Other use cases: high performance, databases, distributed cache stores\n\nStorage Optimized:\n\n* Used for storage intensive tasks - high read and write access to large data sets\n* Use cases: databases, OLTP system, distributing file systems\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/031-explain-each-of-the-following-instance-types-compu.txt aws-compute/d03a5a7521b6 aws-compute easy aws, fundamentals What is Amazon Web Services (AWS) and what are its core service categories? Amazon Web Services (AWS) is a collection of cloud computing services by Amazon, providing on-demand infrastructure and platforms (compute, storage, databases, networking, etc.) on a pay-as-you-go model.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/463-what-is-aws.txt aws-compute/d2309a3107c0 aws-compute medium aws, ami, auto-scaling What are Auto Scaling Groups and how do they work in AWS? Auto Scaling Groups: They automatically adjust the number of instances in response to changing demand. They maintain the desired number of instances even if one fails and can dynamically scale based on rules or policies.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/424-what-are-auto-scaling-groups-and-how-do-they-work-.txt aws-compute/d2d8c0acab92 aws-compute hard aws, placement-groups For each of the following scenarios choose a placement group strategy: * High availability is top priority - Spread\n * Low latency between instances - Cluster\n * Instances must be isolated from each other - Spread\n * Big Data applications that are partition aware - Partition\n * Big Data process that needs to end quickly - Cluster\n\nRemember: Cluster = low latency (same rack). Spread = high availability (different racks). Partition = large distributed workloads (separate failure domains). projects/knowledge/interview/aws/098-for-each-of-the-following-scenarios-choose-a-place.txt aws-compute/d371fab6a0b8 aws-compute easy aws, compute "What is an ""Auto Scaling Group""?" Automatically adjusts EC2 instances to meet demand.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/482-auto-scaling-group.txt aws-compute/d3abfbafd241 aws-compute medium aws, ec2 What are some use cases for using EC2 hibernate option? * Save RAM state\n* Service with long time initialization\n* Keep long-running processes\n\nRemember: EC2 instance naming: family (m=general, c=compute, r=memory, t=burstable) + generation + size. Example: m6i.xlarge = 6th gen Intel general purpose.\n\nGotcha: always use the latest generation for better price-performance. m6i is cheaper AND faster than m5. projects/knowledge/interview/aws/085-what-are-some-use-cases-for-using-ec2-hibernate-op.txt aws-compute/d5b36932981b aws-compute easy aws, serverless "What is ""AWS Lambda""?" A serverless compute service that runs code in response to events.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/468-aws-lambda.txt aws-compute/d74463ea4732 aws-compute hard aws, auto-scaling You have two instance running as part of ASG. You change the desired capacity to 1. What will be the outcome of this change? One of the instances will be terminated.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/203-you-have-two-instance-running-as-part-of-asg-you-c.txt aws-compute/da533d8e8858 aws-compute medium aws, auto-scaling, ec2 What is an Auto Scaling Group (ASG)? An Auto Scaling Group is a group of EC2 instances managed together for scaling and availability. You define conditions or schedules for scaling (adding or removing instances) based on load (CPU, etc.), and the ASG will launch or terminate EC2 instances to maintain the desired capacity or to react to demand spikes.\n\nRemember: ASG = min + desired + max capacity. CloudWatch alarms trigger scaling policies. Desired adjusts between min and max. projects/knowledge/interview/aws/474-what-is-auto-scaling-group.txt aws-compute/de3aeaa01232 aws-compute hard aws, ec2 Are there any disadvantages in using instance store over EBS? Yes, the data on instance store is lost when they are stopped.\n\nRemember: EBS volume types: gp3 (general purpose, baseline 3000 IOPS), io2 (high IOPS, up to 64000), st1 (throughput HDD), sc1 (cold HDD). gp3 is the default choice for most workloads. projects/knowledge/interview/aws/047-are-there-any-disadvantages-in-using-instance-stor.txt aws-compute/df9b85eb5dce aws-compute medium aws, reserved-instances For how long can reserved instances be reserved? 1 year or 3 years. Reserved Instances offer significant discounts (up to 72%) over On-Demand pricing in exchange for a commitment to a specific instance type, region, and term length. Longer terms yield deeper discounts.\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU. projects/knowledge/interview/aws/073-for-how-long-can-reserved-instances-be-reserved.txt aws-compute/e1ec88ed0070 aws-compute medium aws, ec2, reserved-instances What EC2 reserved instance types are there? Standard RI - most significant discount + suited for steady-state usage\nConvertible RI - discount + change attribute of RI + suited for steady-state usage\nScheduled RI - launch within time windows you reserve\n\nLearn more about EC2 RI [here](https://aws.amazon.com/ec2/pricing/reserved-instances)\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/072-what-ec2-reserved-instance-types-are-there.txt aws-compute/e42c32d2e3de aws-compute medium aws, ec2, spot-instances You need an instance for running workloads. You don't care if they fail for a given moment as long as they run eventually. Which pricing model would you use? Spot instances. The discount potential is the highest compared to all other pricing models. The disadvantage is that you can lose the instance at any point so, you must run only workloads that you are fine with them failing suddenly.\n\nGotcha: check the instance type's network bandwidth, EBS bandwidth, and vCPU-to-memory ratio before choosing. The cheapest instance isn't always the most cost-effective. projects/knowledge/interview/aws/064-you-need-an-instance-for-running-workloads-you-don.txt aws-compute/e8b49a1ab3b6 aws-compute medium aws, lambda Which of the following set of languages Lambda supports? - Python, Ruby, Go, Node.js, PowerShell, C#\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/127-which-of-the-following-set-of-languages-lambda-sup.txt aws-compute/ef08a1b91d07 aws-compute medium aws, ec2, placement-groups "What are ""Placement Groups""?" "[AWS Docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html): ""When you launch a new EC2 instance, the EC2 service attempts to place the instance in such a way that all of your instances are spread out across underlying hardware to minimize correlated failures. You can use placement groups to influence the placement of a group of interdependent instances to meet the needs of your workload.""\n\nRemember: Cluster = low latency (same rack). Spread = high availability (different racks). Partition = large distributed workloads (separate failure domains)." projects/knowledge/interview/aws/096-what-are-placement-groups.txt aws-compute/f41df6df02da aws-compute easy aws, ec2 What is an instance type? the instance type that you specify determines the hardware of the host computer used for your instance\nRead more about instance types [here](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html)\n\nRemember: MCRT — M (general), C (compute), R (memory/RAM), T (burstable). Think 'My Computers Run Tasks.' projects/knowledge/interview/aws/028-what-is-an-instance-type.txt aws-compute/f53875ca7f79 aws-compute easy aws, sns What is Simply Notification Service? "AWS definition: ""a highly available, durable, secure, fully managed pub/sub messaging service that enables you to decouple microservices, distributed systems, and serverless applications.""\n\nRead more about it [here](https://aws.amazon.com/sns)\n\nRemember: right-sizing is the #1 cost optimization. Use AWS Compute Optimizer to identify over-provisioned instances. Most workloads use less than 40% of their allocated CPU." projects/knowledge/interview/aws/340-what-is-simply-notification-service.txt aws-compute/f61244eb87b9 aws-compute medium aws, ec2, lambda "True or False? ""Consumers"" can be only EC2 instances" False. They can be Lambda functions and even on-premise instances\n\nRemember: EC2 instance naming: family (m=general, c=compute, r=memory, t=burstable) + generation + size. Example: m6i.xlarge = 6th gen Intel general purpose.\n\nGotcha: always use the latest generation for better price-performance. m6i is cheaper AND faster than m5. projects/knowledge/interview/aws/334-true-or-false-consumers-can-be-only-ec2-instances.txt aws-compute/fb1f96119593 aws-compute hard aws, ami, ec2 When you launch EC2 instances, it takes them time to boot due to commands you run with user data. How to improve instances boot time? Consider creating customized AMI with the commands from user data already executed there. This will allow you launch instance instantly.\n\nGotcha: user data runs only on first boot (unless you configure cloud-init for every boot). It's base64-encoded and limited to 16 KB. projects/knowledge/interview/aws/385-when-you-launch-ec2-instances-it-takes-them-time-t.txt aws-compute/fb9cd6f0685c aws-compute easy aws, ami, ec2 What is an AMI (Amazon Machine Image) in AWS? "Amazon Machine Images is ""An Amazon Machine Image (AMI) provides the information required to launch an instance"".\nRead more [here](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AMIs.html)\n\nRemember: AMI = Amazon Machine Image. It's a snapshot of an EC2 instance: OS, software, config. Think 'golden image.'" projects/knowledge/interview/aws/024-what-is-ami.txt aws-compute/fd4d6e5441fb aws-compute medium aws, placement-groups What Placement Groups strategies are there? * Cluster: places instance close together in an AZ.\n* Spread: spreads the instance across the hardware\n* Partition: spreads the instances across different partitions (= different sets of hardware/racks) within an AZ\n\nRemember: Cluster = low latency (same rack). Spread = high availability (different racks). Partition = large distributed workloads (separate failure domains). projects/knowledge/interview/aws/097-what-placement-groups-strategies-are-there.txt aws-compute/fdabe7b7e17f aws-compute easy aws, ami, auto-scaling What is dynamic Scaling policy in regards to Auto Scaling Groups? A policy in which scaling will occur automatically based on different metrics.\n\nThere are 3 types:\n\n1. Target Tracking Scaling: scale when the baseline changes (e.g. CPU is over 60%)\n2. Step Scaling: more granular scaling where you can choose different actions for different metrics values (e.g. when CPU less than 20%, remove one instance. When CPU is over 40%, add 3 instances)\n3. Scheduled Actions: set in advance scaling for specific period of time (e.g. add instances on Monday between 10:00 am to 11:00 am) projects/knowledge/interview/aws/206-what-is-dynamic-scaling-policy-in-regards-to-auto-.txt aws-compute/fdc40badecf3 aws-compute medium aws, lambda True or False? In AWS Lambda, you are charged as long as a function exists, regardless of whether it's running or not False. Charges are being made when the function is executed for the time it takes to execute and compute resources it uses.\n\nRemember: Lambda = serverless functions. Pay per invocation + duration. Max 15 minutes runtime, 10 GB memory, 512 MB /tmp storage. projects/knowledge/interview/aws/126-true-or-false-in-aws-lambda-you-are-charged-as-lon.txt --- ## Wiki Navigation ### Related Content - [AWS EC2](../../../../library/topics/aws-ec2/index.md) (Topic Pack, L1) — AWS EC2