I think the phrase "target web service" from the article is misleading. This is about passing part of the client's IP address to the authoritative nameserver for the for the target web service. From my understanding the following is an example- Let's say I'm on the east coast, I'm using Google DNS on the west coast as my DNS server, and I want to load foo.edgecast.com. foo.edgecast.com has two servers, one on the east coast and one on the west coast. When I perform a lookup for foo.edgecast.com I talk to Google's recursive resolver which then talks to Edgecast's authoritative nameserver. Without EDNS edgecast doesn't get any information about me; it just knows the request came from Google on the west coast, so it gives out the IP address of their west coast server. With EDNS, Edgecast's gets enough of my IP address from Google to know that I'm on the east coast, so it gives out their east coast server's IP address.
AAaaahhhh... THIS makes sense. SO it's not the actual web server that's getting my truncated IP, it's the web server's provider's NAMESERVER. So if I'm hosting a website, but not its nameserver (say I'm using godaddy or whathaveyou for that), only godaddy's nameserver would get the truncated IP if my site shows up on google's search page; not my actual web server.
