System Preferences in macOS may leave you to conclude that you can’t configure multiple NTP servers for your Mac. However, you can configure multiple NTP servers.
Your Mac isn’t all that good at keeping time, and over time it will slowly drift away from what every other computer considers to be the correct time. To compensate for our computers’ inability to tell time accurately, we rely on internet time-servers to correct and update the correct time. There are plenty of available free Network Time Protocol (NTP) servers around the world, and macOS will by default only connect to a single time-server operated by Apple.
When is it useful or necessary to configure multiple NTP servers
Configuring multiple time-servers will increase the reliability and accuracy of your Mac’s timekeeping abilities. On unreliable and slow networks, it can be especially useful to configure more than one time-server to improve accuracy.
Some managed networks, like a university network, may block public time-servers — like the ones operated by Microsoft — and only allow the use of their own internal time-server. However, this internal server is unlikely to be available if you bring your device home or onto any other network. Ideally, you would want to keep using a public time-server and only add the university time-server as an additional time source.
How to add multiple NTP servers in macOS
In System Preferences: Date and Time, you might expect to see two fields for the primary and secondary time-server. Many network appliances and routers use this setup. However, in macOS there’s only one field but one field is all you’ll need:
- Open the System Preferences app: Date and Time
- Click the lock to unlock the preference pane, if needed
- Enable the “Set date and time automatically” option
- Enter the IP or DNS addresses of your preferred time-servers followed by a period character, and separate multiple entries with commas.
E.g. “pool.ntp.org., time.apple.com., time.windows.com., time.google.com.”
The changes are applied as soon as you close the preference pane.
The above example configures macOS to pull time information for the hundreds of time servers in the NTP Pool project; as well as the time servers operated by Apple, Google, and Microsoft. This should provide plenty of redundancy.
The trailing period is strictly speaking optional, but it’s the preferred format that’s used consistently by Apple tools that interact with the system’s NTP settings. Sticking with Apple’s format may help avoid compatibility issues with system upgrades down the line.
You can also enter the IP or DNS addresses of your preferred time-servers directly in the NTP configuration file at /private/etc/ntp.conf. The NTP client configuration file takes one server entry per line, e.g. “server 0.pool.ntp.org.”
The instructions in this article apply to macOS 10.12 ‘Sierra’ and newer. Check out the Windows version of this tutorial.