dns
EDNS CDN DNS resolution geolocation performance
EDNS Client Subnet Explained: How It Improves CDN Performance and DNS Accuracy
Mark Zhang
August 13, 2026
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DNS Has a Location Problem
When a user in London visits a website served by a CDN, their query usually goes to a recursive resolver assigned by their ISP. That resolver processes the lookup and forwards it to the authoritative name server. The problem? The authoritative server sees the resolver's IP address, not the user's