NTP Servers

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The network time protocol (NTP) is used to synchronize the time on the computers in a network. Accurate time is necessary for the successful operation of time sensitive applications such as Active Directory.

By default, FreeNASĀ® is pre-configured to use three public NTP servers. If your network is using Active Directory, ensure that the FreeNASĀ® system and the Active Directory Domain Controller have been configured to use the same NTP servers.

Figure 4.3a shows the default NTP configuration for FreeNASĀ®.

Figure 4.3a: Default NTP Configuration


If you wish to change a default server to match the settings used by your network's domain controller, click an entry to access its "Edit" button. Alternately, you can delete the default NTP servers and click "Add NTP Server" to create your own. Figure 4.3b shows the "Add NTP Server" screen and Table 4.3a summarizes the options when adding or editing an NTP server. ntp.conf(5) explains these options in more detail.

Figure 4.3b: Add or Edit a NTP Server


Table 4.3a: NTP Server Options

Setting Value Description
Address string name of NTP server
Burst checkbox recommended when Max. Poll is greater than 10; only use on your own servers i.e. do not use with a public NTP server
IBurst checkbox speeds the initial synchronization (seconds instead of minutes)
Prefer checkbox should only be used for NTP servers that are known to be highly accurate, such as those with time monitoring hardware
Min. Poll integer power of 2 in seconds; can not be lower than 4 or higher than Max. Poll
Max. Poll integer power of 2 in seconds; can not be higher than 17 or lower than Min. Poll
Force checkbox forces the addition of the NTP server, even if it is currently unreachable
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