A lot of new sites created from the same hostname


For a few days I've got a lot of websites created on my multisite network, coming from the same hostname.
- These are sites like "job name + city" (in english this would be like "dallasplumber.mysite.com", "chicagopainter.mysite.com" and so on).
- They all come from the same hostname (blueline.mg).
- And these sites are just created. I mean the site is created, then nothing more is done on the site (but sometimes the user logs one more time, some hours after the creation).

I really wonder what's the point of doing this. I know it could be a way for someone to create some fake sites, for backlinks or adsense ads (for exemple).

I'm using Antisplog so I guess I could mark all these sites as spams as soon as they are created.

But really my question is:
Why do you think someone is creating all these sites on my network?
Maybe there is some reason I don't know about?

Thanks for your input :wink:
Best Regards