SQS Queue
Massive buffer holding 200 requests. Place after WAF to smooth DDoS spikes,
or before Compute to prevent overload. Cheap insurance against traffic bursts.
Flow: WAF → SQS → ALB or ALB → SQS → Compute
ElastiCache (Redis)
Caching layer with 35-65% hit rate. Cache hits complete instantly without
hitting DB/S3. Upgrade tiers for higher hit rates. Great for reducing DB costs.
Flow: Compute → Cache → DB/S3