10 More Discussions You Might Find Interesting
1. Red Hat
Hi,
I have two ntp servers in my cluster and I want all the nodes in my cluster to sync with either of the ntp servers or just one. Unfortunately it keep rotating the sync, between my ntp server 1, ntp server 2 and local. Is there anyway I can change the sync to avoid local?
# ntpq -p
... (3 Replies)
Discussion started by: pjeedu2247
3 Replies
2. Linux
Hi folks, I have developed a Linux server for my customer. After migrating the server to my customer site, I was trying to sync its time to the NTP time servers at my customer site.
Below is the ntp.conf:
% vi /etc/ntp.conf
# Permit time synchronization with our time source, but do not
# permit... (2 Replies)
Discussion started by: kimurayuki
2 Replies
3. Fedora
hi guys
I have several Red Hat 5.7(7) all of them sync time with two NTP Servers based on Windows but the issue is I configure the NTP service, I start the ntp service and use ntpdate -u to set the time the first time
This is what I do
1. Configure /etc/ntp.conf
restrict default kod... (2 Replies)
Discussion started by: karlochacon
2 Replies
4. Linux
All here, thank you for listening. Now I've set up a Linux NTP server by adding a external windows NTP server in /etc/ntp.conf. Then I start the ntpd daemon. But how often does the Linux NTP server update its time with the external NTP server? I've looked up everywhere but found no information... (1 Reply)
Discussion started by: MichaelLi
1 Replies
5. Red Hat
Hi Expert,
One on my server keep logging this error below, how to fix this issue?
Thank you.
Reggy.
pluton02:/home/reggy --> sudo grep "ntpd" /var/log/messages | tail
Oct 6 00:26:18 pluton02 ntpd: time reset -6.588403 s
Oct 6 00:26:18 pluton02 ntpd: frequency error -512 PPM exceeds... (0 Replies)
Discussion started by: regmaster
0 Replies
6. Solaris
Ok, I have 4 production systems. There is one NTP server for all four systems. In each system there is one Solaris 10 box that points to that NTP server. All of the other machines in the system point to the Solaris 10 machine to get their time sync.
All four Solaris 10 machines have essentially... (2 Replies)
Discussion started by: DeCoTwc
2 Replies
7. UNIX for Advanced & Expert Users
Hello, colleges!
I need to synchronize time on several thousands device (UTM-1 Edge Appliances - All inclusive, all secure, all branch offices.) which don`t understand summer time at all. But in my country summer time are used.
I plan to sync it with NTP server with modificated time: plus one... (2 Replies)
Discussion started by: chmelvv
2 Replies
8. UNIX for Advanced & Expert Users
Hello all,
What would be the most convienint and proper way on syncing up the time and date on Solaris 8 servers with an NTP server?
Any help would be appreciated. Thanks (2 Replies)
Discussion started by: Sunguy222
2 Replies
9. UNIX for Advanced & Expert Users
can anybody tel lme,how to instal NTS -150 on a unix network,it needs some patch to fetch time frm serve,,?? (2 Replies)
Discussion started by: pesty
2 Replies
10. UNIX for Dummies Questions & Answers
Is there a utility which offers the ability to utilize NTP to sync time on machine.
If so please point to man page or web site (3 Replies)
Discussion started by: SmartJuniorUnix
3 Replies
ntp_intro(7) Miscellaneous Information Manual ntp_intro(7)
NAME
ntp_intro - Network Time Protocol (NTP) introductory information
DESCRIPTION
The Tru64 UNIX software supports two time services: Network Time Protocol (NTP) Time Synchronization Protocol (TSP)
Because it can be traced to clocks of high absolute accuracy, NTP provides a more accurate time service than TSP. By contrast, TSP syn-
chronizes time to the average of the network host times. TSP is an acceptable time service if your system is not on the Internet and does
not have access to a highly accurate time server; otherwise, NTP is recommended.
Network Time Protocol
The Network Time Protocol (NTP) provides accurate, dependable, and synchronized time for hosts on both wide area networks (like the Inter-
net) and local area networks. In particular, NTP provides synchronization traceable to clocks of high absolute accuracy, and avoids syn-
chronization to clocks keeping bad time.
Hosts running NTP periodically exchange datagrams querying each other about their current estimate of the time. Using the round-trip time
of the packet, a host can estimate the one-way delay to the other host. (The assumption is that the delay is roughly equal in both direc-
tions.) By measuring the one-way delay and examining the timestamps that are returned with the NTP packet, a host computes the difference
between its clock time and that of the host it queried.
A host queries a remote host several times over a period and feeds the results from the multiple samples to a digital-filtering algorithm.
The algorithm provides a more accurate estimate of the delay, clock offset, and clock stability than could be obtained with a single sam-
ple.
NTP messages also contain information about the accuracy and reliability of the time sources. An NTP host connected directly to a highly
accurate time source, such as a radio receiver tuned to a time code signal broadcast by a government agency, is called a stratum 1 server.
Every other NTP host adopts a stratum number that is one higher than the host from which it sets its own time. For example, a host syn-
chronized to a stratum 1 server becomes a stratum 2 host. Stratum determination is done automatically, and the stratum of a host can vary
as its connectivity changes.
A host running NTP combines various information to decide which of the hosts it queried provides the time it believes to be the most accu-
rate. This information includes the output of the digital-filtering algorithm and the stratum numbers of the hosts it queried. By commu-
nicating with several other hosts, an NTP host can usually detect those hosts that are keeping bad time, and is able to stay synchronized
even if some of the other hosts become unavailable for long periods.
In practice, NTP is able to synchronize clocks to within a few milliseconds even over wide area networks spanning thousands of miles. To
obtain even greater accuracy, use the NTP_TIME kernel option. See System Administration for more information.
You can optionally use a high-resolution clock, enabling the time returned by the clock_gettime routine to be extrapolated between the
clock ticks. The granularity of the time returned will be in microseconds. To use the high-resolution clock, use the MICRO_TIME kernel
option.
For detailed information on NTP, see Network Time Protocol (Version 3) (RFC 1305).
Time Synchronization Protocol
The Time Synchronization Protocol (TSP) is the protocol used by the daemon. In its simplest application, the TSP servers on a broadcast
network (for example, an Ethernet) periodically broadcast TSP packets. The hosts on the network elect one of the hosts on the network run-
ning TSP as a master. The master then controls the further operation of the protocol until it fails and a new master is elected. The mas-
ter collects time values from the other hosts and computes the average of all the times reported. It then sets its own clock to this aver-
age, and tells the other hosts to synchronize their clocks with it.
TSP quickly synchronizes all participating hosts. However, because TSP does not trace time back to sources of known accuracy, it is unable
to correct for systematic errors. If a clock drifts significantly, or if a mistake is made in setting the time on a participating host,
the average time calculated and distributed by the master can be affected significantly.
For information on setting up the network time services, refer to Network Administration.
RELATED INFORMATION
Commands: ntp(1), ntpdate(8), ntptrace(8), timedsetup(8), xntpdc(8)
Functions: ctime(3)
Files: ntp.conf(4), ntp.drift(4), ntp.keys(4)
Daemons: timed(8), xntpd(8)
Network Time Protocol (Version 3) (RFC 1305)
Network Administration
System Administration delim off
ntp_intro(7)