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The recommended way to use NTP is to run a daemon which will continue to run in the background ensuring your clock is accurate and to have it reference multiple
by bradfa 5y ago
The recommended way to use NTP is to run a daemon which will continue to run in the background ensuring your clock is accurate and to have it reference multiple time sources (or a known stratum 1 source, like an atomic clock, WWV station, GPS, etc).
If you're just syncing your clock once at boot, Google's time servers are probably fine to use, any time server is probably fine to use. Your hardware clock is going to drift over time but lots of times that's perfectly OK.
A pool server that's off by an hour would get kicked out of the pool within probably 20-40 minutes and not allowed back in until it was reporting the correct time for a reasonable duration. The current pool monitoring seems to go at a cadence of around 20 minutes to cycle through all the servers validating them. You can have a look at the log of the monitoring of one of my NTP pool servers: https://www.ntppool.org/scores/165.227.219.198/log?limit=200 https://www.ntppool.org/scores/165.227.219.198/log?limit=200
- bradfa 5y agoFor some pretty graphs, you can have a look at what the pool monitoring does for my pool servers: https://www.ntppool.org/a/bradfa https://www.ntppool.org/a/bradfa
- shaicoleman 5y ago> The recommended way to use NTP is to run a daemon which will continue to run in the background ensuring your clock is accurate You'd might not want to have a daemon running in the background or install extra software in certain circumstances. If you're using a lightweight solution such as systemd-timesyncd or ntpdate+cron it will only query one server, and you end up with the wrong time for ~30 minutes, which can cause major downtime or data corruption in certain circumstances. Even if you're able to use a better client like chrony, it still doesn't solve the issues with leap seconds without extra configuration, which can cause the time to jump or move backwards, which can cause major downtime, e.g. https://blog.cloudflare.com/how-and-why-the-leap-second-affected-cloudflare-dns/ https://blog.cloudflare.com/how-and-why-the-leap-second-affe... https://www.techspot.com/news/49229-leap-second-bug-amazon-ec2-outage-brought-down-major-websites.html https://www.techspot.com/news/49229-leap-second-bug-amazon-e...
- bradfa 5y agoYes, adding ntpd or chrony is another package but they really aren’t that big or burdensome on modern embedded systems. If you can fit systemd you can probably fit a real time daemon, too. I could understand if you’re running in a system with single digit MB of ram or flash, maybe you can’t fit them, but those sizes systems today are quite rare.