Suddenly, I started seeing a blocked URL under the tab of SITE DIAGNOSTICS while viewing my adsense account. The URL blocked does not belong to me!! What does this mean actually? Is someone trying to use my adsense PUB code on an URL which has got blocked? Please help
Check the website's source code, and if you find your adsense code on their website, then ask them to remove it. Aside that you have function called "allowed websites" in your adsense account. Add all your sites there, so that even if someone copy your adsense code and use it on their websites, you'll be safe because impressions and click wont count for those sites, which are not added in your "Allowed Sites".