To access yoursite.com hosted on IIS on hosts machien from with in Ubuntu virtual machine.
Go to hosts machine (Windows)
Navigation to Settings >> Network & Internet >> Change adapter options
Right click the adapter you are using and go to "Internet Protocol Version 4 (TCP/IPv4)"
Note down that ip and add that ip for your site in etc hosts of Ubuntu machine. You can following the following blog for that https://codeasp.net/blogs/ubuntu/8247/how-to-modify-etc-hosts-in-ubuntu
For the above example the row should be
After making the above change you should be able to access your site hosted in IIS on host machine from with in Ubuntu machine.