--- title: "timed: what it is, why it uses the network, and whether to block it · Kilobat" url: "https://kilobat.app/processes/timed" description: "timed keeps a Mac's clock correct with NTP. What its tiny traffic to time.apple.com is, and why blocking it causes certificate errors." --- Core networking # What is timed? `timed` keeps the Mac's clock correct. It uses NTP, the Network Time Protocol, so it sends small requests to a time server, by default Apple's. Process: `timed` · Made by Apple · Applies to: macOS 14 Sonoma and later. Checked on macOS 27.2. · Checked: 1 November 2026 ## Short answer Part of macOS. It keeps the clock correct with NTP, so it sends small requests to a time server such as time.apple.com. Don’t block Don't block it. A wrong clock makes valid certificates look expired, so secure websites and apps fail. Path `/usr/libexec/timed` launchd label `com.apple.timed` Signing identifier `com.apple.timed` ## What it is The man page says that `timed` “maintains system clock accuracy by synchronizing the clock with reference clocks via technologies like NTP”. It first appeared in macOS 10.13. It reads the NTP server from `/etc/ntp.conf`. The Date & Time settings change that server. The program is `/usr/libexec/timed`. Its launchd property list, `com.apple.timed`, runs it as the `_timed` user, every hour, and when Airplane Mode changes. ## Why it uses the network - **Clock synchronization.** It asks a time server for the correct time. Apple lists UDP port 123 for NTP. - **Regular checks.** Its launchd property list starts it every hour and when Airplane Mode changes. Each start can mean a short exchange with the time server. - **Apple's time servers.** Apple lists `time.apple.com` for all its devices, and `time-macos.apple.com` for macOS only. ## How much is normal The requests are tiny. A time request and its answer are a few small packets. Its launchd property list asks for a run every hour, so you see short, regular bursts. If you set another time server in Date & Time, its requests go there instead. ## When it uses a lot, and why - **Never heavy.** NTP packets are small. If `timed` shows large traffic, measure it with the steps below and look at what else runs. ## Is it safe to block? Don’t block Don't block it. A wrong clock makes valid certificates look expired, so secure websites and apps fail. What breaks if you block it - The clock drifts. Secure websites can then show certificate errors, such as ERR_CERT_DATE_INVALID. - Sign-ins and other features that check the time may fail. - Apple doesn't list a fallback for macOS without NTP. Blocking means a firewall rule that refuses its connections. Don’t quit or disable a macOS process to save data: macOS starts it again, and other features depend on it. ## Reduce its use 1. There is nothing to reduce. Keep it on. See [“This Connection Is Not Private” and certificate warnings on a Mac](https://kilobat.app/guides/connection-not-private-mac). 2. To change the time server, choose Apple menu › System Settings › General › Date & Time. 3. On a network that blocks NTP, set a time server that the network allows. 4. Don't quit `timed` in Activity Monitor. macOS starts it again. ## See how much it uses 1. Open Activity Monitor from Applications › Utilities. Click Network. 2. Type `timed` in the search field. The Sent Bytes and Rcvd Bytes columns show what it moved since it started. 3. In Terminal, watch only this process. Press d to show the change per second, and q to quit. ``` nettop -p 'timed' -P ``` ## With Kilobat 1. In the Kilobat app list, search for `timed`. Its row shows the live rate and what it moved today. 2. In Connections, click the ⓘ button on one of its rows. The popover shows this page’s short answer, without going online. 3. In Terminal, ask the same question. Add `--json` for scripts and agents. ``` kilobat explain 'timed' ``` 4. Show its traffic over one day. ``` kilobat bandwidth 'timed' day ``` 5. Through MCP, an AI agent asks `explain_connection` with the process name. It gets the same facts. The live view and the explanations are free. History in the app needs Kilobat Pro. Blocking needs Pro and the network filter: see the [network filter](https://kilobat.app/docs/blocking#filtering), [Protection](https://kilobat.app/docs/blocking#protection) and the [hotspot data saver](https://kilobat.app/save-hotspot-data). ## Hosts it contacts Apple and the maker document these hosts for this feature. A process can also contact others; Kilobat’s Connections tab shows what it actually opens on your Mac. - [time.apple.com](https://kilobat.app/hosts/time-apple-com): Apple's time servers. Macs use NTP on UDP port 123 to set their date and time from them. ## Questions **What happens if the clock is wrong?** Secure websites can show certificate errors, such as ERR_CERT_DATE_INVALID in Chrome. See [NET::ERR_CERT_DATE_INVALID in Chrome on Mac](https://kilobat.app/guides/err-cert-date-invalid). **Why do I see timed every hour?** Its launchd property list, `com.apple.timed`, has a start interval of 3600 seconds. That is one hour. **Can I use my company's time server?** Yes. Set it in Date & Time. `timed` reads the server from `/etc/ntp.conf`, which that setting changes. ## Sources - timed(8), man page installed with macOS 27.2 - launchd property list com.apple.timed, macOS 27.2 - [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) - [Apple Support: Use Apple products on enterprise networks](https://support.apple.com/en-us/101555) - [Apple Support: TCP and UDP ports used by Apple software products](https://support.apple.com/en-us/103229) Checked on 1 November 2026. ## Related - [trustd](https://kilobat.app/processes/trustd): Part of macOS. It checks certificates for every app, and asks certificate authorities whether a certificate was revoked. Its connections are small. - [configd](https://kilobat.app/processes/configd): Part of macOS. It keeps the Mac's network configuration and gets its IP addresses with DHCP, so it sends small amounts of traffic to the router. - [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)