Can I install/reinstall macOS without an internet connection?

Questions
1

If I want a totally offline Mac setup, is this possible?

2

No:

3

Wow. Does anyone here think it’s a privacy concern?

4

Yes, unless you trust apple 100%.

If you hardware support it, you may install linux on it as an alternative.

5

I cannot speak on behalf of others.

6

You’re going to connect it to the internet later anyway so I don’t really see the issue.

7

Theres a couple ways though some of them will require an internet connection of some type. The old way was using MacOS Server on your network and then using NetBoot and NetInstall, unfortunately this method is no longer working with current Macs.

  • Using Apple Configurator you can connect two Macs via USB-C cable and place the target machine in DFU mode, which will let you reinstall the firmware and the latest version of macOS. (This method will require no internet connection, but will require two Macs)

  • Content Caching is another solutions, but requires at least the serving Mac to have an internet connection to have the latest updates and installers available, this feature can be found in System Settings > General > Sharing, this is a nice feature as it lets you serve local caches over your network rather than going through Apples servers, which allows for faster deployment and installation.

  • Using an MDM such as Jamf, Kandji or Mosyle paired with Automated Device Enrollment (ADE).

  • And last a built in feature within MacOS which is erase All Content and Settings, which will return the Mac back to it’s original factory state without having to reinstall the entire operating system.