I did not know about GGC, and that seems cool (and similar to the Netflix approach of putting content servers inside ISP networks). However, this does not explain why I get an address pointing to my ISP network when I query via OpenDNS, which is definitely outside of my ISP network and is an intermediate recursor (so, from the perspective of the nameservers for google.com, the query is not coming from a Virgin Media address range).

EDIT: And from the GGC documentation, it does not seem as if the ISPs are required to serve content from the in-ISP nodes to customers outside the ISP, which is what this would look like.

OpenDNS uses edns-client-subnet, which passes the DNS client IP subnet (/24) with the recursion request. Google still knows you are on Virgin Media from behind OpenDNS.

http://www.afasterinternet.com/howitworks.htm

Now THAT, is amazing - and perfectly explains what's going on. I operate several nameservers of my own for various domains, some owned by me, some not, and I'd not heard of that. I am happy with your answer, thanks!

Yup. More info here: https://datatracker.ietf.org/doc/draft-ietf-dnsop-edns-clien...

Your command log shows you are not using OpenDNS, but Google's Public DNS (8.8.8.8). Are you confusing the two?

I tried again with OpenDNS at the suggestion of someone else in this thread with the same results - see my other comments.