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14. Exam Readiness.md

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Exam readiness

Tips

  • Most questions are scenario based
    • First rule out answers you know for sure are wrong
    • Remaining answers: Understand which one makes the most sense.
  • No penalty for guessing
  • Don't over-think it
    • If solution seems feasible but highly complicated, it's probably wrong.
  • You can come back to questions with flag feature
  • For learning services more, read each service's FAQ
    • Cover a lot of the questions asked in the exam
  • If AWS provides a service/functionality within service => Use it instead of creating a bespoke service.
  • 65 questions will be asked in 130 minutes
    • 2 minutes per question

Axioms

  • Reliable/resilient storage = EBS, EFS, S3
    • For EBS
      • Small, random = SSD
      • Large, sequential = HDD
  • Durable = S3
  • Low latency access = EBS
  • Reproducible = Spot instance, S3 one zone IA
  • Decoupling = SQS, SNS
    • Only once = SQS FIFO or SWF
  • Multi-tier architecture: ELB, ASG, EC2
  • High availability/fault tolerant =
    • Horizontal scaling, vertical scaling
    • ASG that span over many AZ (sent to ELB)
    • DynamoDB (HA by default)
    • RDS (multi-AZ needs to be enabled)
      • Availability = Sync replication, Scalability = async
  • Performant storage and databases =
    • 💡GP2, IO1 for EBS
    • 💡EFS, S3
  • Caching = ElastiCache, CloudFront, API Gateway, DAX for DynamoDB
  • Multi-region=Stack Set
  • Elasticity and scalability = ASG, Lambda, CloudWatch for alarms
  • CloudWatch
    • Enhanced monitoring: Metrics within hyper-visor from RDS
    • Detailed monitoring: Send metrics in 1m interval instead of 5.
  • Secure application tiers = Security groups
  • Secure data = KMS, Encryption
  • Cost optimized storage = S3, Pay for what you use, life-cycle rules to move data to cheaper, glacier for long time.
  • Cost optimized compute = Lambda, pay for what you use, reserve long time instances, Spot Instances for short fault tolerant jobs
  • Licensing problems = Microsoft + Oracle e.g. BYOB=Dedicated host
  • Operational excellence = Serverless

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