Country of website

How is it determined?

[DerekH]

Background

Just a simple question. I'm in the UK, so use google.co.uk for many searches. I see UK results on my sites (a .co.uk and some .org.uk sites), and also on those of friends and families, who use free ISPs with .com/~username style URLs. A .com address, but from a UK ISP.

In the past I'd read how Google knew which sites were UK and I must confess that I promptly forgot it as it had no relevance other than as a curiosity value.

My question
I have a friend (no comments please!) with a site in which some new pages are in the index, but with no title, no snippet and no cache - presumably pages that have been seen and are on Google's "ToDo" list.

If I do an "inurl" search on any DataCenter, I get identical results - many cached pages, and these few stragglers on the end.

If I do an "inurl" search on Google.co.uk, those untitled pages are missing. Google must treat them as a non-UK page, even though it knows where to find them.
Any idea why this should be?

DerekH

[linear]

There are databases available (including free ones) that map IP address space onto countries. They use data from the registries that allocate theaddress space for the various regions, and the picture changes a bit over time. So it's just a lookup to find your country if one knows your IP.

But the IP of a server may not be from the country of the webmaster, if you see what I mean. Lots of people from outside the US host in the US because of favorable prices.