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I'm having a problem with some Android tablets being unable to synchronise the time when connected to our wireless network. This is in a school and fairly heavily locked down, so it's probable that they are being blocked from accessing something that they need to in order to synchronise the time.

These are Wi-Fi only devices, so they can't set the time from a GSM provider or anything, meaning they must be using something else, presumably NTP. If it's NTP, how can I view/change the time server used?

The devices are Android 4.0.1. I'm not sure what make/model they are but will try and find out.

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    At the very least, This question on StackOverflow tells us that it does use NTP. However, it doesn't describe a method for a normal user to find or set the default server.
    – dotVezz
    Commented Dec 9, 2013 at 18:12

3 Answers 3

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We confirmed with the device manufacturer that the devices use NTP to sync the time with pool.ntp.org. After a bit of research of my own, I discovered that NTP is configured in /system/etc/gps.conf. You have to be root to edit this file, but I was at least able to confirm that the information given to us was correct.

We have opened the firewall to traffic going to pool.ntp.org, and so far all of the devices have kept in sync, so it looks like this has worked as intended.

Thanks to http://forum.xda-developers.com/showthread.php?t=1200089 for the info on the NTP config file.

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dotVezz has already commented that NTP is used.

If so, then you can use ClockSync, which lets you set the NTP server. HOWEVER, you need to sync manually. Automatic sync is supported only with ROOTED devices.

ClockSync synchronizes device system clock with atomic time from Internet via NTP (Network Time Protocol). Useful if provider doesn't support NITZ, sends incorrect time or if your device/ROM has heavy clock drift. There are 2 modes: automatic for root users and assisted manual mode for users without root (rootless mode).

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  • Unfortunately manually syncing the clocks isn't a suitable solution in this case. The devices are for use in a classroom and we need them to sync to the correct time automatically.
    – toryan
    Commented Dec 10, 2013 at 11:48
  • @toryan If you root the devices, it would be possible.
    – geffchang
    Commented Dec 10, 2013 at 12:11
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You can DNS override the pool.ntp.org entry in your corporate DNS infrastructure, and make that an alias/CNAME to your own internal NTP source/service. That will allow the internally connected android devices to sync with NTP without modification of the device itself

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  • That is an interesting suggestion, thankyou.
    – toryan
    Commented Aug 11, 2016 at 23:16
  • Could you explain more in detail how to do this?
    – GeekInDisguise
    Commented Jun 30, 2019 at 11:44

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