---
title: "time.apple.com: what it is and what breaks if you block it · Kilobat"
url: "https://kilobat.app/hosts/time-apple-com"
description: "time.apple.com and time-macos.apple.com are Apple's time servers, which keep a Mac's clock right over NTP. What breaks if you block them."
---

Core networking

# time.apple.com

`time.apple.com` and `time-macos.apple.com` are Apple's time servers. Apple lists them as “Used by devices to set their date and time”, over NTP on UDP port 123.

Run by Apple · Ports: 123 UDP · Checked: 1 November 2026

## Short answer

Apple's time servers. Macs use NTP on UDP port 123 to set their date and time from them.

Don’t block

Don't block them unless the Mac uses another time server. A clock that drifts makes secure websites fail with certificate errors.

Matches

`time.apple.com` `time-macos.apple.com`

A name with `*.` covers every name under it: `*.push.apple.com` matches `1-courier.push.apple.com`.

## What it serves

Apple's enterprise host list names `time.apple.com` for all its platforms and `time-macos.apple.com` for macOS only, both on UDP port 123.

On a Mac, [`timed`](https://kilobat.app/processes/timed) keeps the clock right with NTP. It reads its server from `/etc/ntp.conf`, which the Date & Time settings change.

Each request and answer is a few small packets.

## Processes that use it

- [timed](https://kilobat.app/processes/timed): Part of macOS. It keeps the clock correct with NTP, so it sends small requests to a time server such as time.apple.com.

## What breaks if you block it

Don’t block

Don't block them unless the Mac uses another time server. A clock that drifts makes secure websites fail with certificate errors.

What breaks if you block it

- The Mac's clock drifts. Secure sites can then show certificate errors, such as ERR_CERT_DATE_INVALID.
- Sign-ins and other features that check the time may fail.

With Kilobat Pro and the network filter, you can block a host for every app or for one app: in Connections, select a connection and choose Block. Apple’s own services are never blocked by Kilobat’s [Protection](https://kilobat.app/docs/blocking#protection) lists.

## Notes

On a network that blocks these servers, set a time server that the network allows in System Settings › General › Date & Time.

## Apple’s rules for its hosts

Apple’s list, [Use Apple products on enterprise networks](https://support.apple.com/en-us/101555), says that devices open these connections, not Apple’s servers. Apple services fail any connection that uses HTTPS interception, so a proxy that inspects TLS should leave Apple’s hosts alone.

If a firewall allows hosts by name, allowing `*.apple.com` covers most Apple services, Apple says. A firewall that works only with addresses can allow `17.0.0.0/8` for IPv4, and `2403:300::/32`, `2620:149::/32` and `2a01:b740::/32` for IPv6.

To see which app on your Mac opened a connection to this host, use Kilobat’s Connections tab, or the [agent network log](https://kilobat.app/docs/agents#agent-network-log) for AI agents.

## Sources

- [Apple Support: Use Apple products on enterprise networks](https://support.apple.com/en-us/101555)
- [Apple Support: Set the date and time automatically on your Mac](https://support.apple.com/guide/mac-help/set-the-date-and-time-automatically-mchlp2996/mac)
- timed(8), man page installed with macOS 27.2

Checked on 1 November 2026.

## Related

- [NET::ERR_CERT_DATE_INVALID in Chrome on Mac](https://kilobat.app/guides/err-cert-date-invalid)
- [“This Connection Is Not Private” and certificate warnings on a Mac](https://kilobat.app/guides/connection-not-private-mac)