I have the same issue. I would expect NOT to see COX private IP address like 10.51.0.1 from the cox network. I have also confirmed that I can see their 10.10.10.0-254 range. (try to ping 10.10.10.# from your residential or business). In my experience, it appears that they have allowed internal IP space to be seen on the public space. I will call them again and post an update as to why this is happening.
All, I am on call now with Tyler with Cox business support. I have also forward this to support@coxmail.com along with my screen shots of traceroutes and pings showing that internal IP spaces of 10.x that is causing us pain. I have asked them to update here as I have many cox residential and business customers complaining about the same thing.
