@Andrea Lazar,
Looking at the last few days, its Content Spammer bots that have picked up on your URL. There is nothing much you can do.
These bots normally try to post spam in your comments, but they havent been able to. (Most likely because you need to be a member to post a comment. Im not quite sure why FAA gets targeted so much by Content Spammer bots, as they can never really post anything here, normally its wordpress sites that get such activity, but the bots just blindly keep trying).
So, all these bots are doing is wasting FAA bandwidth.
That 'can' cause FAA problems, as they have to buy bigger servers and more bandwidth to cope with the extra load.
This isnt only a problem for FAA, this generally effects any web site out there. There is a massive amount of automated and bot activity that is probably making up a very large percentage of the internet traffic.
On my own servers, a large amount of visits come from bots, the real big ones that continue to hit me, that I know about I tend to block down at the IP level in the OS. Since my servers are on MS Azure, I get charged for CPU usage and network activity, so it costs me money and performance of my site with all these bots if I just let the continue.
Most of these IPs that are hitting your image are also hitting my own servers, trying to post comments to my WordPress blogs. So I have more info myself on them as I can actually see what they try to post, and its just comments with links in them trying to advertise.
In Detail from the last few days on your url, if you click each IP, you can see the report about them from Project Honey Pot (a service that helps detect bots):
Romania
195.211.155.158
195.211.155.208
New York,NY
192.95.38.49
Beijing, China
120.37.230.248
120.37.210.58
120.37.207.25
Brisbane, Asia/Pacific Region
27.153.137.165
27.159.229.114
27.159.229.32
Guangzhou
110.82.170.197
Alchevsk, Ukraine
91.200.12.45
I also cross referenced on other sites, like myip.ms & stopforumspam.com
HTHs,
Rob.