Ask a question about the PHP multi-site path

Ask for a PHP multi-site path problem. The website structure is as follows: root & nbsp; | -- images & nbsp; | -- B & nbsp; | -- the main domain name root.com of the cwebsite, and then there are N other domain names, such as B .comc.comb.com, pointing to the directory. ask for a question about the PHP multi-site path.
The website structure is as follows:
Root
| -- Images
| -- B
| -- C

The website's primary domain name root.com has N other domain names, such as B .com c.com.
B .com points to directory B c.com points to directory c

Server environment window + iis
How can I allow B .com c.com programs to call images in the images folder? How to enable another domain name as a resource domain name

The server environment can be changed to window + apache/Nginx. the server can be changed to linux (the cost of replacing the system is very high. if the server environment is not changed, it will not be changed. Involves a lot of additional development issues)

I hope you can give me some advice. How can we implement the above things. If you think it is simple, you only need to provide an address for your ideas and relevant learning materials ~ Not much. Extra points

------ Solution --------------------
In the iis Manager, right-click all the websites and choose "virtual directory"> "create a virtual directory." images "points to [d]:/root/images.

Apache sets virtual directory
ALIAS/images "[d]:/root/images"

Nginx unknown