AWS Cloud Services

Master AWS Cloud Services for software engineering interviews. AWS Fundamentals Global Infrastructure AWS operates in Regions — geographic locations each containing 2 or more Availability Zones (AZs). An AZ is one or more physically separated data centers with independent power, cooling, and networking. Key rule: Deploy across at least 2 AZs for high availability. A single-AZ deployment has a single point of failure. Edge Locations (200worldwide) serve CloudFront CDN content from locations close to end users. Shared Responsibility Model This is a critical interview concept: Customer Responsible For OS patching (EC2) Network infrastructure IAM configuration Managed service internals (RDS engine) Security group rules | Mnemonic: AWS manages security OF the cloud. You manage security IN the cloud. IAM: Identity and Access Management IAM controls who can do what to which AWS resources. Core components: User: Long-term credentials for a person or application Group: Attach policies to multiple users at once Role: Temporary credentials assumed by services or users Policy: JSON document with Allow/Deny statements Policy evaluation logic: Explicit Deny Allow implicit Deny. If no policy allows an action, it is denied by default. AWS CLI Basics Java SDK v2: STS — Who Am I? IAM Best Practices Enable MFA on the root account — never use root for daily tasks Grant least privilege — start with read-only, add as needed Prefer roles over access keys for services running on AWS Rotate access keys every 90 days Use AWS Organizations Service Control Policies for multi-account guardrails Billing and Cost Management AWS Free Tier: 750 hrs/month EC2 t2.micro, 5 GB S3, 1M Lambda invocations Cost Explorer: Visualize spending by service, region, tag Budgets: Alert when spending exceeds threshold Trusted Advisor: Checks for cost, security, and performance improvements Interview tip: Always mention the Shared Responsibility Model and IAM least privilege in any AWS security question. These two concepts appear in nearly every senior-level interview. Python Implementation