NTP stands for Network Time Protocol, and it is an Internet protocol used to synchronize the clocks of computers to some time reference.

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Tracing chain of NTP servers

For educational purposes I wanted to trace a chain of NTP servers, e.g. 0.de.pool.ntp.org back to a stratum 1 NTP server. How can I do this? I found ntptrace, but it doesn't work: /home/xyzdragon# ...
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Linux-NTP: What could cause high offset in some servers while all of them reside on the same network sigment and are configured the same?

I've installed a new NTP server and configured all Hadoop clients to use it. I've been told by the Hadoop Engineers that an offset of maximum 3 seconds is mandatory for the cluster to work properly. ...
7
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1answer
212 views

DST Morocco, a way to trick NTP server

From several years Morocco have been using GMT without DST, in the past years, our government reactivated the use of DST. In the first years, the DST was a mess, different periods, starts, ends, so ...
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59 views

NTP can't synchronise

Okay so I tried syncing a windows clients clock to the ubuntu ntp server i just set up, but it gets a time out, when trying. So I went on the ubuntu server and looked at syslog: Apr 10 13:15:01 ...
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1answer
22 views

Best practices for time syncing a WS2012R2 domain controller that is a Hyper-V virtual machine?

What are generally the best practices for keeping time in a WS2012R2 domain controller? Right now I have left it as installation and honestly, there is no problem ("If it aint broke, don't fix it") ...
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31 views

Time Zone keeps changing after sync with PDC in different site

Background: I have a single domain, running in 2 sites that is connected using Site-to-Site VPN. Site A is running in time zone 2:00+ UTC Site B is running in time zone 4:00+ UTC DCs are correctly ...
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20 views

Windows Active Directory follow linux NTP server for Time sync [duplicate]

I have a Windows infrastructure hosted in a restricted environment. We have apps that need to be with exact time sync with the external time source. To sync the Windows AD with external time source, I ...
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2answers
49 views

how to get a subset of NTP servers from *.pool.ntp.org?

I am doing some reliability tests and needed a list of NTP servers from fr.pool.ntp.org (or any other geographic or national pool). I queried the pool 100 times but only got 13 unique servers (out of ...
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3answers
330 views

Where do computers/servers in a Windows Domain get their time settings from? [duplicate]

I have 5 Windows Server 2012 servers and around 100 computers in our domain. Recently I noticed that the time on the servers and computers is around 30 seconds fast. Where do servers and computers ...
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1answer
49 views

“NTP socket is in use” messages from ntpdate in syslog

In cron.log I can see that ntpdate is being triggered from a cron job which is running daily at 23:15 Mar 10 23:15:01 seitan /USR/SBIN/CRON[22407]: (root) CMD (/etc/network/if-up.d/ntpdate) But ...
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2answers
45 views

Can I configure a server to use a user port(>1023) for NTP?

Can a linux server be configured to use a high source port(above 1023) for NTP synchronization with a Stratum 1/2 server? Are there any disadvantages to doing this?
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231 views

Risk of starting NTP on database server?

I've heard rumors of bad things happening to database and mail servers if you change the system time while they are running. However, I'm having a hard time finding any concrete information on actual ...
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24 views

ntpd logging debug to ntpd.log

using ntpd 4.2.6p5 on redhat 6.5 How do I configure /etc/ntp.conf to generate debug messages to logfile? in /etc/ntp.conf I have logfile /var/log/ntpd.log but that only does very basic entries. ...
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1answer
54 views

date and sleep during leap second [closed]

Did you ever watch what happens with a sleep during a leap second or what date will show us? Most UNIX systems can handle a sleep with a fraction of a second and the date command can display ...
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39 views

NTP offset warning when no NTP server is defined and NTP not running?

I just want to preface by saying that I am still learning linux and don't have too much experience with it. My job requires me to monitor an alert system for our clients hosts that are running our ...
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125 views

Cisco SG300 SNTP servers always down

I'm trying to setup the SNTP of a new Cisco SG300-48 Switch in L3 mode. So far I have enabled the Main Clock Source (SNTP Servers) option (Administration -> Time Settings), set my time zone and ...
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38 views

What causes ntpq refid CRYP when authentication is successful?

I have five servers that I'm configuring for production use based on a configuration we've recently tested. The servers are RHEL6 with NTP version 4.2.4p8@1.1612-o. Right now, though, I'm trying to ...
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2answers
444 views

What happens when DC cannot reach external time server?

We have a small Windows 2012 R2 domain with a single DC. The DC is advertising as a time server, and the clients are syncing just fine. The DC is getting its time from an external time server, and ...
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68 views

Why my server on Digital Ocean woke up with a wrong time?

Today one of my servers hosted on Digital Ocean (the only one hosted there) is reporting wrong time. It's two hours late. sudo dpkg-reconfigure tzdata # then I set up the timezone to Europe/Rome ...
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24 views

Using RTC to synchronize ntpd when offline

I need a stable configuration, presumably using ntpd, to keep system clock as precise as possible. Background: I have several embedded devices (arm9) running linux (currently: 3.16.1 / debian 7.2) ...
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43 views

Server Migration 03 -> 12

I have run into a wall and out of ideas. Here's the situation. I have a client that has a old '03 DC with a 12 replicating the '03 server. It is out dated and has to many group policies and stuff it ...
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79 views

chronyd peer not syncing

I would like to configure two my servers as chronyd ntp peers. Both servers run on amazon ec2, one on centos 7, one on rhel 7 -what is minimal chrony peer configuration ? I cant use my other server ...
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1answer
78 views

Resync windows time after a long power outage

I'm facing the following situation: We have a computer with Windows 8 Standard Embedded. The machine is an industrial computer that doesn't have a CMOS Battery but a capacitor (a Gold Cap acting as a ...
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43 views

Ubuntu server is randomly having large time sync issues

It seems that randomly the time on my server will jump forward several hours. This happens randomly and the only way I've found to fix it is to manually force an NTP call. I don't see anything out of ...
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2answers
53 views

What does this shell script mean? [closed]

#!/bin/bash /usr/sbin/ntpdate ntp.jst.mfeed.ad.jp I found such a script file,maybe it is used to confirm the time, can you explain it in detail?
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1answer
109 views

ntpd keeps adding local servers while being told not to

I'm configuring ntp inside a corporate network. I've done restrict default ignore restrict -6 default ignore and listed servers explicitly (I'm using public servers from pool.ntp.org). I also ...
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2answers
57 views

ntp authentication - MD5 - freeBSD

NTP claims to support md5 authentication. The docs I've found aren't clear enough for my level of luserhood. How would I go about using it, with a collection of freebsd clients, and a couple of ...
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2answers
158 views

How to have ntpd serve only my local subnet

I have a few servers with public Internet IP addresses like A.B.C.x. One of my hosts (A.B.C.10) runs ntpd and I have it syncing it's time from europe.pool.ntp.org. Now I only want to allow hosts ...
5
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2answers
136 views

Proper NTP configuration for a few servers

I have about 20 Linux servers in a small network and I need their clocks decently close to each other (e.g. within 20msec). I've started with every one of them synced to europe.pool.ntp.org and the ...
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1answer
104 views

NTP Version Check

How can I check other NTP server's NTP version without query the server? NTPv3 and NTPv4 network packet is different, and I know I can just catch the packet and analysis it when ntpd is doing sync. ...
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1answer
137 views

NTP not sync the time continuously, Have to restart the service of NTP then it SYNC in Ubuntu

I am facing one problem. NTP server not sync the time automatically. If I change the the time of system then NTP server not able to correct it. After reboot the service of NTP it sync the time ...
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1answer
157 views

How to update NTP-deamon on a Debian Squeeze (Proxmox 2.x)?

Because of security issue in NTP (CVE-2014-9295) I need to update NTP-deamon on a Debian Squeeze (it is the Proxmox 2.x installation). The problem is that it is a productional system and I can not ...
5
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2answers
261 views

Windows Server 2012 time keeps setting itself 12 minutes ahead

Our Active Directory server has a problem whereby the time keeps setting itself 12 minutes ahead of the real time. This causes authentication issues on the network. I have tried syncing to an ...
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2answers
32 views

Does windows server provide a standards-based NTP service?

We use a PHP script for syncing time against a NTP time server. All of it works, but when working with windows server, the script fails. Is there a modified version of NTP working inside the original ...
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1answer
115 views

Main DC is no longer NTP or hold FSMOs

Good Afternoon, We two virtual DC and one local physical read only DC. When we moved our data center offsite with a warm backup site we p to v our DC’s and DC1 was the master schema. While ...
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1answer
24 views

How to accommodate two sets of NTP servers

I have a case where, within one company, half of the devices synchronize to a set of NTP servers (including a GPS based one), and the other one on another set (also including stratum 1 servers). I ...
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1answer
46 views

Neglected services on old DC - how to move to new DC?

We have installed a new Server 2012. The new server: DC3 (192.168.0.3), has been promoted, and is now our main DC (includes : DNS, DHCP) Schema master DC3.domain Domain naming master ...
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177 views

Server times off by over 1 minute after recently syncing

I manually synced the times (and matched hardware times) on two servers A and B. NTP was running on both machines, so I made sure the /etc/ntp.conf files were identical (the time servers on B were ...
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22 views

Why does (should?) dispersion prevent ntp from updating?

Yes, root dispersion is the maximum clock time difference that was ever observed between the local clock and the root clock. I'm still not sure what this means exactly. The situation that develops is ...
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2answers
594 views

Synchronize clock with NTP while online, and with RTC while offline?

Is there a existing mechanism that synchronizes a linux system with NTP while online, and with a predictably drifting RTC while offline? We operate remote "collectors": embedded Linux systems that ...
2
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1answer
251 views

configuration to use gps time with no internet connection

I use ntp with a GPS device with PPS on port /dev/ttyS0. All seems to be fine if the machine is connected to the internet. Output looks correct. But if there is no internet connection I get: $ ntpq ...
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1answer
168 views

udev rule running setserial low_latency don't work

My server runs Ubuntu 14.04.1. I created udev rules in /etc/udev/rules.d/09-pps.rules to get GPS with PPS support work. KERNEL=="ttyS0", SYMLINK+="gps0", MODE="0666" KERNEL=="ttyS0", ...
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1answer
129 views

NTP offset between PDCe and DC (Both Hyper-V)

I'm facing an issue, here is the context: 1 PDCe (192.168.1.3 and Hyper-V virtualized) is set as NTP server, its source for time is VM IC Time Synchronization. 1 DC (Hyper-V virtualized) is ...
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1answer
277 views

Windows Server NTP Authenication

I have setup an NTP Server on a Windows Server 2008. The Time synchronization works with Windows Clients and Non Domain Clients but now i have switches that want to authenticate against NTP Server and ...
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72 views

Time Sync Issue for vm PDC on HyperV

I am a bit new the this forum. Not sure where to start but I basically found an article on this forum about HyperV Time Sync for VM Domain Controller. The owner of the post described the problems that ...
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84 views

RedHat ntp offset becomes bigger over time

I have a strange issue with a server. It is configured to use 2 servers, just like all the other server (the config is the same for a couple of server and they are all working except this one) and it ...
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1answer
95 views

How should I manage and troubleshoot NTP issues?

For some time now I've been fighting with some NTP issues in my company's network and I'm having a hard time to understand how the commands combine with the service. For example: In the server's ...
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1answer
222 views

How can I have ntpdate ignore skew?

During a server bootstrap process, I want to explicitly run ntpdate rather than rely on the ntp daemon. However, the clock can be severely skewed at this point in time, which causes an error when ...
0
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1answer
83 views

How can I test that I am correctly setting a new ntp server?

I have a config script that is configuring the ntp server of a machine (which is running Ubuntu 14.04) by stripping lines matching ^server .* from /etc/ntp.conf and adding a new line server ...
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1answer
55 views

ntp daemon seems useless and why my server date time is far behind my local time

I've installed ntp daemon in ubuntu to sync my date time with the network time. Now my time on the server is 11:00 while my PC date/time is 19:30. Now all my transactions date/times are logged ...