AWS infrastructure is organized into regions, Availability Zones (AZs), and edge locations. Choosing the right region affects latency, pricing, and which services are available.
Regions and Availability Zones
- Region — e.g.
us-east-1(N. Virginia); independent geographic area - AZ — isolated data center(s) within a region; use multiple AZs for high availability
- Local Zones / Wavelength — extensions for ultra-low latency (preview awareness)
Most services are regional—an EC2 instance in eu-west-1 is separate from one in ap-southeast-1.
Edge and content delivery
CloudFront caches content at edge locations close to users. Route 53 provides DNS. Global services include IAM and Route 53 hosted zones (with regional nuances).
Explore regions via CLI
aws ec2 describe-availability-zones \
--region us-east-1 \
--query 'AvailabilityZones[].ZoneName' \
--output tablePractice: Use the AWS Free Tier or a dedicated sandbox account. Run optional CLI steps in a terminal with aws configure using a non-production IAM user—never root keys.
Choosing a region
- Place resources near users for lower latency
- Check data residency / compliance requirements
- Confirm the service you need exists in that region
- Compare pricing—some regions cost more than others
Important interview questions and answers
- Q: Region vs AZ?
A: Region is geographic; AZ is an isolated failure domain within that region. - Q: Why multi-AZ?
A: Survive single data center failure—RDS Multi-AZ and ALB across AZs are common patterns.
Self-check
- What is an Availability Zone?
- Name two factors when picking an AWS region.
Tip: Always note your current region in the Console header—resources are regional.
Interview prep
- Region vs AZ?
Region is geographic; AZ is an isolated data center group within a region for HA.
- Why multi-AZ?
Survive single facility failure—common for RDS and Auto Scaling across AZs.