Hi Folks,
With Mojave coming (and me on call for
upgrading 14 Macs with 8 grandchildren)
was thinking of Content Caching and
having them access locally rather than
downloading 14 times (on my data cap!)
Anyone have experience with this?
Have read as much doc as I could find
and I am still confused.
Will this work? Do I have to do something
to the “clients” to make them look “locally”
rather than go across the wire?
Thanks for any help - and wish me luck 
I have Content Caching enabled on one of my iMacs for the same reason. The cache is totally transparent, but it seems to be working. My cache has several gigabytes of content stored in it. And I noticed today that the first iOS 12 upgrade I did waited hours to begin downloading the update, but subsequent devices finished downloading in under a minute.
Once you enable the cache, macOS contacts Apple’s servers to inform them that you have a cache running and what your internal and public IP addresses are. Then when any devices with the same public IP address (any devices connected to your home network) want to download content (system updates, app downloads, icloud content, etc) Apple’s servers tell the device to talk to the Mac running Content Caching. If the content isn’t in the cache yet, it’s downloaded from Apple, and stored in the cache for the next device that needs it.
The cache configuration can be changed in System Preferences/Sharing if you want to limit the content that is cached or serve clients only on specific networks.
You could also create a Mohave usb installer to be sure you are not going through your data cap.
Content Caching seems to be a magic pudding no one can quite explain. The profile of this function has been raised by recent mention in MPU and also Online Screencasts. I thought it would be very useful for me given how I operate, but if I am reading the table in Activity Monitor correctly the benefit seems marginal at the moment. Nevertheless the caching doesn’t take up all lot of space so even if benefits are minimal, … no real harm is done, … as far as I know!