How do PREF cookies determine user location?

[XXYY]

Hello, all,

I've been reading about how google PREF cookies, and have read that they reveal the users' location, but I haven't been able to find out HOW they do this, and more importantly how to prevent this (aside from simply blocking the cookie). Does it use one's IP address? Or is it like fingerprinting and just uses your timezone?

[gordo]

I couldn't really find out HOW they do it, but here is what I found on them.


http://blogs.wsj.com/digits/20*2/02/28/the-google-cookie-that-seems-to-come-out-of-nowhere/

The cookie, which is named PREF and contains a unique ID number, is not an advertising cookie. But it “cannot be disabled by consumers without disabling core browser security features such as anti-phishing protection&#822*; or blocking cookies....

More: According to the documents, the NSA and its British counterpart, GCHQ, are using the small *****ing files or "cookies" that advertising networks place on computers to identify people browsing the Internet. The intelligence agencies have found particular use for a part of a Google-specific *****ing mechanism known as the “PREF&#822*; cookie. These cookies typically don't contain personal information, such as someone's name or e-mail address, but they do contain numeric codes that enable Web sites to uniquely identify a person's browser.
http://www.washingtonpost.com/blogs/the-switch/wp/20**/*2/*0/nsa-uses-google-cookies-to-pinpoint-targets-for-hacking/