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For example I never log from university (I'm a teacher) or other public networks where people might be visiting my site and clicking from the same IP as the one I'm using
Another way is maybe by tracking cookies.
You click on an ad -> cookie.
When you login to adsense, it will verify the cookies and it will se if you click on the links from your site.
I login from different networks when I'm on the road and never observed a decline in earnings because of it.
Seriously, why do you need to know this? You can assume that Google has a variety of automated tools and filters in place to watch for invalid clicks. They've been doing this for several years now and you can assume they've gotten very good at it. Isn't that enough?