EDNS Client Subnet
EDNS Client Subnet or ECS is a DNS extension that allows a recursive DNS resolver to specify the network subnet for the host on which behalf it is making a DNS query. This is generally intended to help speed up the delivery of data from content delivery networks, by allowing better use of DNS-based load balancing to select a service address serving the content expected to be hosted at that domain name, when the client computer is in a different network location from the recursive resolver.
The EDNS client subnet mechanism is specified in.
, DNS resolution service providers supporting EDNS Client Subnet include Google Public DNS, OpenDNS and Quad9.
