Introduction When CDN geographic routing sends users to the wrong region, they experience high latency and slow page loads. This defeats the purpose of having a global CDN.

Symptoms - Users in Europe served from US edge locations - High latency for users far from the serving edge - CDN logs showing unexpected edge location usage - Users reporting slow performance in specific regions - Latency-based routing not working as expected

Common Causes - DNS resolver location not matching user location - Geo-IP database outdated - Edge location not available in user's region - Latency-based routing not enabled - CDN not deployed in user's geographic region

Step-by-Step Fix 1. **Check which edge location is serving the user': ```bash curl -s https://cdn.example.com/cdn-cgi/trace | grep loc # Or check response headers for edge location curl -sI https://cdn.example.com/ | grep -i "x-amz-cf-pop|cf-ray|x-cache" ```

  1. 1.**Enable latency-based routing':
  2. 2.```bash
  3. 3.# Route 53 latency-based routing
  4. 4.aws route53 change-resource-record-sets \
  5. 5.--hosted-zone-id <zone-id> \
  6. 6.--change-batch file://latency-routing.json
  7. 7.`

Prevention - Use latency-based DNS routing - Deploy CDN edge locations in all major user regions - Monitor latency by geographic region - Regularly update geo-IP databases - Test CDN performance from multiple global locations