What's changed: In-scope coverage: added compute/scaling/storage (EC2 Auto Scaling/AWS Auto Scaling/ECS/Fargate/Lambda/S3)
4.2Implementing and Choosing Load Balancers
Distribute traffic—understand ALB (L7), NLB (L4), GWLB, target groups/health checks, and cross-zone load balancing. Choose by layer and requirements.
Elastic Load Balancing offers ALB (application), NLB (network), and GWLB (gateway). Choose by the OSI layer they operate at and your requirements.
4.2.1Three load balancer types
- ALB (L7): HTTP/HTTPS. Path/host-based routing, WAF, TLS. For web apps/microservices.
- NLB (L4): TCP/UDP/TLS. Ultra-low latency, static IP, massive connections, preserves source IP. For non-HTTP.
- GWLB: transparently inserts virtual appliances (firewall/IDS/IPS) to inspect traffic.
- Target groups/health checks: group targets and automatically remove unhealthy ones.
Common on ANS-C01: route by path/host = ALB (L7), static IP / ultra-low latency / TCP·UDP = NLB (L4), and insert appliances like firewalls = GWLB. Choose NLB when static IP is required and ALB for content-based routing.
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