7 questions foundWhat is Amazon EC2 and what does it provide to users needing virtual compute capacity?
Beginner Amazon EC2, or Elastic Compute Cloud, provides resizable virtual servers, called instances, in the cloud, letting you choose the operating system, amount of CPU and memory, storage, and networking configuration you need, and scale that capacity up or down as your requirements change, without needing to purchase, install, or maintain any physical hardware yourself.
aws ec2 run-instances --image-id ami-12345678 --instance-type t3.medium --key-name my-key
Real-world example A startup launches a handful of EC2 instances to host its web application, scaling up the number and size of instances as its user base grows, without ever needing to purchase or manage physical servers.
Common follow-ups: What is the difference between an EC2 instance and a physical server?;How quickly can a new EC2 instance be launched?
Auto Scaling Groups;VPC & Networking
What are the main EC2 instance families, and how do you choose the right one for a specific workload?
Beginner EC2 instance families are optimized for different types of workloads, including general purpose instances offering a balance of compute, memory, and networking for a wide variety of applications, compute optimized instances for CPU intensive workloads like batch processing, memory optimized instances for workloads like in memory databases that need large amounts of RAM, and storage optimized instances for workloads requiring high, sequential read and write access to very large datasets.
aws ec2 describe-instance-types --filters Name=instance-type,Values=m5.*
Real-world example A company running a memory intensive in memory caching layer chooses a memory optimized instance family, while their standard web application servers use a general purpose instance family that provides a good balance for typical web traffic.
Common follow-ups: How do you determine which specific instance size within a family is right for your workload?;What is the performance difference between different generations within the same instance family?
Auto Scaling Groups;Amazon ElastiCache (Redis & Memcached)
What is the difference between On Demand, Reserved, and Spot Instance pricing models in EC2?
Intermediate On Demand pricing lets you pay for compute capacity by the hour or second with no long term commitment, offering maximum flexibility at the highest per hour rate, Reserved Instances require a one or three year commitment in exchange for a significant discount compared to On Demand pricing, and Spot Instances let you bid on spare, unused EC2 capacity at a steep discount, with the tradeoff that AWS can reclaim that capacity with only a short notice if it is needed elsewhere.
aws ec2 describe-spot-price-history --instance-types m5.large --product-descriptions 'Linux/UNIX'
Real-world example A company runs its steady, predictable production web servers using Reserved Instances for cost savings, while running its fault tolerant, interruptible batch processing jobs on Spot Instances to further reduce costs for that specific workload.
Common follow-ups: How much warning does AWS provide before reclaiming a Spot Instance?;What is the difference between Reserved Instances and Savings Plans?
AWS Cost Management & Billing;Auto Scaling Groups
What is the difference between EBS backed and instance store backed EC2 instances in terms of data persistence?
Intermediate An EBS backed instance stores its root volume on Amazon Elastic Block Store, meaning the data persists independently of the instance's lifecycle and survives a stop and start cycle, while an instance store backed instance uses temporary storage physically attached to the underlying host, meaning any data stored there is permanently lost if the instance is stopped or terminated, making EBS backed instances the appropriate choice for the vast majority of workloads requiring persistent data.
aws ec2 describe-volumes --filters Name=attachment.instance-id,Values=i-1234567890abcdef0
Real-world example A database server relies on an EBS backed instance to ensure its data remains intact even if the instance needs to be stopped for a maintenance window, whereas a purely temporary caching layer uses instance store volumes since losing that data on restart is acceptable.
Common follow-ups: What happens to data on an instance store volume if the instance is simply rebooted rather than stopped?;When would instance store volumes actually be the better choice despite their lack of persistence?
S3 & Storage;RDS & Databases
How do EC2 placement groups help optimize instance performance for specific networking or availability requirements?
Intermediate EC2 placement groups let you influence how your instances are physically placed on underlying hardware, with a cluster placement group packing instances close together within a single Availability Zone for the lowest possible network latency between them, a spread placement group placing instances on distinct underlying hardware to minimize the risk of correlated hardware failures affecting multiple instances at once, and a partition placement group grouping instances into logical partitions that do not share underlying hardware, useful for distributed systems like Hadoop that need to isolate failure domains.
aws ec2 create-placement-group --group-name my-cluster-group --strategy cluster
Real-world example A high performance computing workload requiring extremely low latency communication between nodes uses a cluster placement group, ensuring all its instances are physically located as close together as possible within the same Availability Zone.
Common follow-ups: What are the tradeoffs of using a cluster placement group in terms of availability?;When would a spread placement group be more appropriate than a cluster placement group?
Auto Scaling Groups;VPC & Networking
How does EC2 Nitro System architecture improve performance, security, and efficiency compared to older EC2 hypervisor based virtualization?
Advanced The Nitro System offloads much of the virtualization overhead, such as networking and storage processing, from the main host CPU onto dedicated Nitro hardware components, delivering performance that is nearly identical to running directly on bare metal hardware, while also improving security by using a Nitro Security Chip that enforces strict isolation between the underlying hardware and customer instances, preventing even AWS operators from having direct access to customer instance memory or data.
aws ec2 describe-instance-types --filters Name=hypervisor,Values=nitro
Real-world example A financial services company running latency sensitive trading applications benefits from the near bare metal performance and enhanced security isolation provided by Nitro based EC2 instances, compared to the older generation hypervisor architecture their previous infrastructure used.
Common follow-ups: What specific security guarantees does the Nitro Security Chip provide?;Are all current generation EC2 instance types built on the Nitro System?
AWS Security Hub & GuardDuty;IAM
How should an organization design a comprehensive EC2 rightsizing and cost optimization strategy combining instance type selection, pricing models, and automation?
Advanced A comprehensive strategy typically involves continuously monitoring actual CPU, memory, and network utilization using CloudWatch to identify over provisioned instances, using Compute Optimizer or Trusted Advisor recommendations to right size instance types based on genuine usage patterns, strategically combining Reserved Instances or Savings Plans for steady state baseline capacity with Spot Instances for fault tolerant burst workloads, and automating instance scheduling to stop non production instances outside of business hours, together compounding into significant cost savings without sacrificing necessary performance or availability.
aws compute-optimizer get-ec2-instance-recommendations --instance-arns arn:aws:ec2:us-east-1:123456789012:instance/i-1234567890abcdef0
Real-world example A large enterprise combines Compute Optimizer recommendations for rightsizing, a mix of Savings Plans for baseline capacity and Spot Instances for batch workloads, and automated scheduling that stops development instances every night, together reducing their overall EC2 spending by a substantial percentage without any negative impact on production performance.
Common follow-ups: How do you measure the actual cost savings achieved by a rightsizing initiative over time?;What organizational processes help ensure rightsizing recommendations are actually acted upon consistently?
AWS Cost Management & Billing;Auto Scaling Groups