How does Google know this?

Question

Open google.
If google is not your default homepage, then there will be a link at the very bottom of the google page: MAKE GOOGLE YOUR HOMEPAGE

ok. we click on it and we set google.com, our homepage.
when we re-visit the google site, the link is not there!

how can google know this? what is the trick? how does google know that our default homepage is already set to google, so it does not display this link?

Answer 1

You can get the name of your homepage using JSP.

Answer 2

It's an IP disappearing link. If you would have manually done it, rather than clicked on the link it would have stayed there, once the person clicks on it, they're taken to a different google.

Answer 3

Magic.

Answer 4

cookies maybe