If you run a Drupal site for any length of time you will quickly realise that a few paths that have nothing to do with Drupal will receive a lot of traffic. All of these paths result in page not found errors so the only impact is taking up your server resources. It's common to see paths like wp-login, xmlrpc.php, phpBB/page_header.php, postnuke/article.php, as well as a multitude of others. These requests are clearly bots probing the site to see what sort of CMS is in use and if they can exploit it or not.
It's a bit of a shame that the internet is like this, but it's just one of the things you need to be aware of when managing a website. Users, and more often, bots, will continuously probe your site and servers for exploits. This is why you need to have firewalls and ensure your software is up to date as people are only too willing to crack your site and expose your data.