## The Math Behind Five-Nines (99.999%)
Most startups deploy perfectly into `us-east-1` and forget about it. However, when AWS experiences a regional outage, platforms go entirely offline. Engineering teams must calculate whether the massive monthly cost of running a duplicated server array over in `us-west-2` is mathematically justified based on their hourly revenue stream.
### FAQ
**Q: Why is Active-Active typically 2.5x instead of exactly 2.0x?**
A: Beyond doubling your servers, you must pay for synchronous cross-region database replication network traffic, global load balancers (like Route53), and increased DevOps deployment complexity.