Superfluous strings being appended to URLs

Not to sure about the security bit or the modification, not my field but i thought i might add that that the server i was on was taken down by a DDos attack and the main thing in the log was a get request for an image repeatedly, as well as a few other files.

Anyone else have any ideas? Strangely, I’m seeing this same query string showing up in my logs from multiple IP addresses, but a Google search doesn’t turn up anything informative. Is this some sort of automated scan?

Adding a random query string is a method for forcing the browser to display the latest version of a page rather than one that’s been cached. Not sure why anyone would be doing that…