Quick brush-up. Anchored to what's on your resume (Lambda, VPC, IAM, SQS/SNS, RDS).
Compute
EC2 vs Lambda vs Beanstalk?
EC2 = raw VMs (you manage). Lambda = serverless functions (event-driven, pay-per-invoke, no servers). Beanstalk = PaaS (deploy an app, it manages EC2/scaling/LB for you).
Lambda cold start (your story — know cold)
New execution env must init (for Spring Boot, slow context startup) → adds latency + can hit ~10s init timeout. Fixes: slim the JAR, Provisioned Concurrency (pre-warmed envs), SnapStart (Java snapshot restore). (It’s SAM not SAML.)
Networking & security
What is a VPC?
Your isolated virtual network in AWS — subnets (public/private), route tables, security groups (instance firewall), NACLs (subnet firewall).
IAM — roles vs policies vs users?
Policy = permissions document (JSON). Role = assumable identity with policies (services use roles, e.g. Lambda→S3). User = a person/app identity. Principle: least privilege.
Messaging & storage
SQS vs SNS?
SQS = queue (point-to-point, one consumer pulls). SNS = pub/sub (fan-out to many subscribers). Common combo: SNS→SQS fan-out.
S3 basics?
Object storage, 11 9’s durability, buckets/keys, storage classes (Standard/IA/Glacier), versioning, lifecycle policies.
RDS vs DynamoDB?
RDS = managed relational (Postgres/MySQL/Oracle). DynamoDB = managed NoSQL key-value, single-digit-ms, scales huge. Your resume = PostgreSQL on RDS.
Ops
CloudWatch vs CloudTrail?
CloudWatch = metrics/logs/alarms (observability). CloudTrail = API audit log (who did what).
Drill cards
EC2 vs Lambda vs Beanstalk?::EC2 = raw VMs; Lambda = serverless functions (event-driven); Beanstalk = PaaS that manages the infra for your app.
Lambda cold start fixes?::Slim the JAR, provisioned concurrency (pre-warmed), SnapStart (Java snapshot). It’s SAM not SAML.
SQS vs SNS?::SQS = queue, one consumer pulls; SNS = pub/sub fan-out to many. Combine as SNS→SQS.
IAM role vs policy vs user?::Policy = permissions JSON; role = assumable identity (services use these); user = person/app identity. Least privilege.
CloudWatch vs CloudTrail?::CloudWatch = metrics/logs/alarms; CloudTrail = API audit trail (who did what).