uptimeMonitorWhat Nobody Tells You About Multi-Region Monitoring
We ran checks from 12 regions for a year. Here is what we learned about false positives, routing quirks, and why single-region monitoring is lying to you.
The Single-Region Trap
Most teams start with monitoring from one region. It works — until a CDN edge node in Frankfurt goes down and your US-based monitor says everything is fine while half your European users stare at error pages.
We see this pattern constantly: a team sets up monitoring from us-east-1, gets comfortable, and then scrambles when a regional outage hits.
What 12 Regions Taught Us
After running checks from 12 global regions for over a year, a few things became obvious:
1. Latency Varies More Than You Think
The same endpoint can respond in 80ms from Virginia and 340ms from Singapore. That is not a bug — it is physics. But if your alerting threshold is 200ms, you are either getting false alarms from Asia or missing real degradation in North America.
What works: Set region-specific thresholds. Your p95 from Tokyo will always be higher than your p95 from the same continent as your origin server.
2. DNS Propagation Creates Blind Spots
After a DNS change, different regions see different records for hours — sometimes days. We have watched monitors in Sydney resolve to the old IP twelve hours after a migration while London was already on the new one.
3. False Positives Follow Patterns
We tracked false positive rates across regions for six months:
| Region | False Positive Rate |
|---|---|
| US East | 0.02% |
| EU West | 0.03% |
| AP Southeast | 0.08% |
| South America | 0.12% |
The pattern is clear: the further from major internet exchange points, the noisier your checks get. Factor this into your alerting rules.
The Minimum Viable Setup
You do not need 12 regions on day one. Start with three:
- Your primary user region — where most of your traffic comes from
- A secondary continent — catches CDN and DNS issues
- The region furthest from your origin — your worst-case latency baseline
This catches 90% of regional issues while keeping alert noise manageable.
Correlation Is Your Friend
The real power of multi-region monitoring is correlation. A single region reporting a failure is noise. Three regions reporting the same failure simultaneously is a real incident.
Configure your alerts to require confirmation from at least two regions before paging anyone. Your on-call engineers will thank you.
Written by
Sarah Chen
VP of Engineering. Previously led SRE at Stripe.