One simple question, how do people find that where the site is from?

I have a blog on blogger.
I have an account in payperpost and I saw there one oppertunity which was only available for the UK bloggers.

I wonder how do they know whether one is a UK blogger or not?

 

IP address location.

 

The problem is my site is hosted on blogger.

 

If they are offering only to UK blogger Geographically, then they will track your IP.

If they are offering to UK related blogs, then you should know how they will tell.

 

So, How can I track a IP of a Blog?

 

Add... statscounter (a free counter) they track where visitors come from (site... referring url)

 

I have not added anything like that.
Then how do they know whether I am a uk blogger or not?

 

They can track your *Internet* IP to see if you are located in UK.

 

Yep The Webmaster is right, while you sign up your IP is tracked, other than that you are required to enter your details/country when signing up for PPP.

As a result of this, you require to be having a UK account to get accepted for that opportunity.

Netis