High-Performing and Scalable Networks

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Included in this chapter:

LB	Layer	Protocols	Targets	Best for
ALB	L7 (HTTP/HTTPS)	HTTP, HTTPS, gRPC, WebSocket	EC2, IP, Lambda, ECS	Web / API; path + host routing
NLB	L4 (TCP/UDP)	TCP, UDP, TLS	EC2, IP, ALB	Ultra-low latency; static IPs; source-IP preservation
CLB (legacy)	L4/L7	HTTP, HTTPS, TCP	EC2 classic	Don't use for new designs
GWLB	L3 (IP)	IP (inline transparent)	Network appliances	Inline firewall / IDS / IPS

Cheat sheet

Front HTTP/HTTPS with CloudFront, but reach for Global Accelerator on non-HTTP traffic or fixed IPs
Use Transit Gateway once you have many VPCs, peering for a few, and Direct Connect Gateway when on-prem is in the mix
Pick the load balancer by protocol, IP-pinning, and routing intelligence
Any HTTPS endpoint can be a CloudFront origin, not just S3 or EC2
Transit Gateway is billed per attachment-hour plus per-GB processed
ALB target groups can hold instances, IPs, or Lambda functions
Route 53 latency routing uses a pre-measured edge-to-region table, not live pings
Use CloudFront Functions for lightweight edge logic and Lambda@Edge for the heavy stuff
Global Accelerator: traffic dials shift between regions, weights shift within one
API Gateway: HTTP API by default, REST for advanced features, WebSocket for bidirectional
Add Origin Shield to dedupe origin fetches across regional edge caches
Use Route 53 multivalue answer for DNS-layer load balancing across a small fleet
Turn on Evaluate Target Health to propagate ELB backend health into DNS failover
S3 Transfer Acceleration optimizes upload speed, never cost

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Cheat sheet