Read it, then solve it
Learn the concepts behind the puzzles
Short articles that explain one idea properly: what it is, how it compares with the things it gets confused with, and the traps exams set. Each one ends with a puzzle to test yourself.
- AWSDatabasesRDS Multi-AZ vs read replicas: availability or read scaling?Multi-AZ keeps a standby that takes over on failure; read replicas are copies you can query. How each works, where Aurora and RDS Proxy fit, and exam traps.4 min readSAA-C03
- AWSSecurity and identityCloudFront signed URLs vs signed cookies: which one should you use?Serve private content through CloudFront with a signed link per file or signed cookies for many files. How each works, canned vs custom policies, exam traps.5 min readSAA-C03
- AWSCloud fundamentalsRTO vs RPO and the four AWS disaster recovery strategiesRTO is how long you can be down; RPO is how much data you can lose. Here’s how backup and restore, pilot light, warm standby and active-active compare.4 min readSAA-C03CLF-C02
- AWSStorageS3 storage classes explained: which one should you use?From S3 Standard to Glacier Deep Archive: how often you read data and how fast you need it decide the class. Costs, minimums and exam traps compared.5 min readSAA-C03CLF-C02
- AWSSecurity and identityIAM users, groups and roles: what’s the difference?IAM users have long-term credentials, groups share permissions, and roles hand out temporary ones. Here’s when to use each, and why roles usually win.5 min readSAA-C03CLF-C02
- AWSNetworkingNAT gateway vs internet gateway: what does each one do?An internet gateway is a two-way door to the internet; a NAT gateway is a one-way exit for private subnets. Here’s when you need each one.5 min readSAA-C03CLF-C02
- AWSNetworkingSecurity groups vs network ACLs: which one do you need?Security groups and network ACLs both filter traffic in a VPC, but they work at different levels and remember different things. Here's when to use each.5 min readSAA-C03CLF-C02
- AWSMessaging and integrationSQS delay queues vs visibility timeout: what's the difference?Delay queues, message timers and visibility timeout all hide SQS messages, at different moments and for different reasons. Here's how to tell them apart.5 min readSAA-C03