Redirecting to my reseller's website when enter ip address

When I enter my server ip address to url it's redirecting to my reseller's created website with 302. I don't know why. It must show default ispconfig page if the vhost not found. I searched all config files but I didn't find the problem. Do you have any idea?
This is httpd access_log result:
[CLIENTIPADDR] - - [22/Oct/2018:00:56:50 +0300] "GET / HTTP/1.1" 301 230 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/69.0.3497.81 Chrome/69.0.3497.81 Safari/537.36"

 

Looks like the HTTP answer is 301 Moved Permanently. There seems to be redirection somewhere.
If you access the server with URL that does not exist, the web server shows the website that is first in alphabetical order. You can create a website named aaaa0000.tld (it does not have to exist in name service) and put a suitable index.html file there to indicate the URL used does not exist (at least not on this server).

 

Thank you so much for yoru answer. I see now why redirecting. So I have a question too. Can I redirect to my custom website if the domain not found?

 

If url is not found, it gets directed to the aaaa0000.tld website, if you created that. Otherwise it goes to the website that is first in alphabetical order.

 

Is it exactly "aaaa0000.tld" or "aaaa0000.com" ?

 

That is just an example. You can use any name that is first in alphabetic order.