!!! Overview
[{$pagename}] ([NTP]) functions as part of the [UDP] [protocol] suite, which is part of the [Internet Protocol Suite] defined in [RFC 5905]
Therefore, a computer using [{$pagename}] must have the [Internet Protocol Suite]e loaded. Any computers on your network with [Internet] access can get [time] from [{$pagename}] servers on the [Internet].
[{$pagename}] synchronizes clocks to the [Coordinated Universal Time] ([UTC]) standard, which is the international time standard.
[{$pagename}] introduces the concept of a stratum. A stratum-1 server has an attached accurate time piece such as a radio clock or an atomic clock. A stratum-2 server gets time from a stratum-1 server, and so on.
!! Synchronizing Time on [Linux] or [Solaris]
You can use the xntpd [{$pagename}] ([NTP]) daemon to synchronize time on Linux and Solaris. xntpd is an operating system daemon that sets and maintains the system time-of-day in synchronism with Internet standard time servers.
For more information on running xntpd on Solaris system, see http://docs.sun.com/?p=/doc/806-0625/6j9vfim2v&a=view#xntpd-1m-indx-2.
The NTP daemon is configured by the [/etc/inet/ntp.conf|ntp.conf] configuration file.
For information on running ntpd on Linux systems, see ntpd - Network Time Protocol (NTP) Daemon.
!!Test ntp configuration
{{{
ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
LOCAL(0) LOCAL(0) 10 l 44 64 377 0.000 0.000 0.004
+lolly.dreamcomm 130.88.200.98 3 u 10 1024 377 128.561 4.816 0.387
*chime6.surfnet. .PPS. 1 u 84 1024 377 129.592 4.424 0.150
+www.dynam.ac 203.26.24.6 3 u 38 1024 377 243.739 -22.077 0.246
}}}
!! Network Time Security (NTS)
[Network Time Security] ([NTS]), a mechanism for using [Transport Layer Security] ([TLS]) and [Authenticated Encryption with Associated Data] ([AEAD]) to provide [Cryptographic] security for the [Client-server] mode of the [{$pagename}] ([NTP]).
!! Issues with NTP
We have used ntp for a long time and have always had issues of one sort or another as ntp appears to be intolerant of network issues and fails to perform retries. Here is an excerpt of a typical [NTP] log file showing ntp giving up on the ntp server due to a temporary network outage:
{{{
21 Mar 07:59:57 ntpd[3468]: getaddrinfo: "time.willeke.com" invalid host address, ignored
21 Mar 08:00:19 ntpd[3747]: host name not found: time.willeke.com
21 Mar 08:00:19 ntpd[3747]: couldn't resolve `time.willeke.com', giving up on it
}}}
NTP will, by default then revert to the local clock and NEVER retry the server again. There is a similar issue even if the ntp server is hard coded with an IP address but the ntp server(s) are not reachable for any number of network issues.
There is some documentation of these issues being bugs in the ntp.org buglist:
* [bug 992|https://support.ntp.org/bugs/show_bug.cgi?id=992|target='_blank']
* [bug 987|https://support.ntp.org/bugs/show_bug.cgi?id=987|target='_blank']
As as is said in the 997 bug report, it's not a real fix since there are other issues that need to be dealt with.
!! [Why is Why is Time Important Important|Why is Time Important]?
[Some information on why is Why is Time Important Important|Why is Time Important]?
!! [SNTP] Perhaps a better way
As a result of these issues and the added requirements, we have almost given up on ntp usage.
We have had much better success using [SNTP].
!!Verifying Time Synchronization eDirectory
To verify that time is synchronized in the tree, run DSRepair from a server in the Tree that has at least Read/Write rights to the Tree object.
1. Run the following command:
{{{ ndsrepair -T}}}
!! Details on NTP
For more details on NTP refer to [http://www.ntp.org/]
!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]