3.3 - Core AWS services (EC2, S3, RDS, Lambda)
AWS Certified Cloud Practitioner objective 3.3 is the largest topic and covers the core AWS services. Amazon EC2 provides resizable virtual machines - on-demand compute capacity in the cloud that you can start and stop. Amazon S3 is object storage designed for 99.999999999% (eleven nines) durability, ideal for backups, media and static content. Amazon RDS is a managed relational database supporting engines such as MySQL, PostgreSQL and others, offloading patching and backups from you. AWS Lambda lets you run code without provisioning servers, paying only per request and compute time, which suits event-driven and infrequent workloads. You should recognise each service by what it provides. Expect scenario questions that describe a need - virtual servers, durable object storage, a managed database, or serverless code - and ask which core service - EC2, S3, RDS or Lambda - is the right choice.
Resizable virtual machines = EC2. Object storage, 11 nines durability = S3. Managed relational DB (MySQL/PostgreSQL) = RDS. Run code, no servers, pay per request = Lambda.
Practice questions
1. Which AWS service provides resizable virtual machines (compute capacity) in the cloud?
- Amazon EC2 (correct answer)
- Amazon S3
- Amazon RDS
- Amazon Route 53
Amazon EC2 (Elastic Compute Cloud) offers virtual servers (instances) you can resize and scale. S3=object storage, RDS=managed databases, Route 53=DNS.
2. Which service is object storage designed for 99.999999999% (11 nines) durability?
- Amazon EBS
- Amazon S3 (correct answer)
- Amazon EFS
- Instance store
Amazon S3 stores objects with 11 nines of durability across multiple AZs. EBS=block volumes for EC2, EFS=shared file system, instance store=ephemeral.
3. Which service lets you run code without provisioning servers, paying only per request and duration?
- Amazon EC2
- AWS Batch
- AWS Lambda (correct answer)
- Amazon Lightsail
AWS Lambda is serverless compute: you upload a function and pay per invocation and run time — no servers to manage. Lightsail=simple VPS, EC2=managed VMs.
4. Which fully managed NoSQL database offers single-digit millisecond performance at any scale?
- Amazon RDS
- Amazon Redshift
- Amazon Aurora
- Amazon DynamoDB (correct answer)
DynamoDB is a serverless key-value/document NoSQL database with millisecond latency. RDS/Aurora=relational, Redshift=data warehouse (analytics).
5. Which service distributes incoming application traffic across multiple EC2 targets?
- Elastic Load Balancing (ELB) (correct answer)
- Amazon CloudWatch
- AWS CloudTrail
- Amazon SNS
ELB automatically spreads traffic across healthy targets in one or more AZs, improving availability. CloudWatch=monitoring, CloudTrail=API auditing, SNS=notifications.
6. Which service records account activity and API calls for auditing and governance?
- Amazon CloudWatch
- AWS CloudTrail (correct answer)
- AWS Config
- Amazon Inspector
CloudTrail logs who did what and when (API calls) for auditing. CloudWatch monitors metrics/logs/alarms (performance), Config tracks resource configuration changes.