Apple's tool to reinstall macOS on devices without using local media is a secure feature that allows administrators to reinstall or update the operating system. It is the first step to recovery during implementation.
Many earlier versions, Apple stopped providing physical media versions of its operating system, then it was titled OS X. By moving to a fully digital distribution model, Apple allowed administrators to download a clean copy of the operating system to be able to Install it or upgrade a device, as required. In doing so, administrators could also create an offline installer that could be copied to a USB flash drive to facilitate installations on devices with corrupted operating systems or replaced storage units, which requires a clean installation.
In addition, each Mac with a modern version of macOS / OS X installed on it comes with the ability to update or restore your operating system through a wired or wireless network connection directly from Apple servers, without requiring Download the standalone installer first or create an offline USB installer, with all necessary components downloaded via the Internet first to a temporary partition before starting with the local installation.
Through the last option, known as Internet Recovery, Apple provides not only a current and clean copy of macOS for installation on compatible devices, but also seamlessly integrates firmware updates and, if enrolled in Apple's Device Enrollment Program (DEP), the management profile of that point s the device recently restored on its MDM server suitable for further management from zero touch onwards.
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There are several options available for administrators and users who wish to install or update macOS through Internet Recovery, all of which depends on the versions of macOS you are trying to install, depending on the model of your Apple computer and which operating systems are compatible with specific devices. Next we will review the three methods used to invoke Internet recovery for each scenario.
How to install or reinstall the existing version of macOS
Keyboard combination to maintain during startup: R-Command .
This method is the most common and is used to reinstall macOS according to the latest version of macOS installed on the target device. This is useful when a factory reinstallation of the operating system is performed, such as provisioning an existing device for a new user or initializing the device for use with DEP.
How to install or upgrade to the latest version of macOS
Keyboard combination to maintain during startup: Option-Command-R.
This method should be used when performing a clean installation, usually when updating or replacing a storage unit, or when upgrading to the latest version of macOS compatible with the target device. In the case of a damaged operating system, the second method provides the ability to install macOS cleanly.
How to install or reinstall the version of macOS that comes preinstalled with your Mac
Keyboard combination to maintain during startup: Shift-Option-Command-R .
The main difference between this and the options listed above is that this process will not install the latest version of macOS or provide the latest known installed version of macOS. Instead, this third option will attempt to install the version of macOS (or OS X) that comes with the factory device or the next available version.