About macOS Recovery hosts and ports

When you use macOS Recovery, your computer might need to contact an Apple host server on a specific port. Learn which hosts and ports it might contact.

 This article is intended for network administrators. If you believe that you're affected by an issue related to macOS Recovery hosts and ports, contact your network administrator.

To reinstall macOS with macOS Recovery, you have to connect to the Internet. If your user's computer is behind an external proxy server or firewall, confirm that they can:

  • Resolve DNS for host osrecovery.apple.com and contact it on port 80 (HTTP) and port 443 (HTTPS)
  • Resolve DNS for host oscdn.apple.com and contact it on port 80 (HTTP) and port 443 (HTTPS)

These hostnames might resolve to different IP addresses each time that you use them.

When macOS Recovery connects to the server, it sends information that identifies the hardware model of the computer. It uses this information to determine the correct operating system to install. macOS Recovery doesn’t send any personally identifiable information.

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