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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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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1answer
319 views

NTP: ntpdate to sync time between the PCs on a private network

I have two systems. One acts as Primary/Active and has Internet connection and gets time from NTP server. The second system is Secondary/Passive and has no connection to the external world. Primary ...
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12 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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922 views

Meinberg ntp for Windows - force more frequent updates?

I have a Windows VM that has time drift problems, and left to its own devices will drift by minutes per day. I know there are issues with time on VMs, but I was hoping using the Meinberg NTP service ...
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35 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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32 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
59 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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5 views

NTP compilation failed - without ssl [migrated]

I am trying to cross compile NTP ver 4.2.8 without SSL support. I gave --without-crypto while configuring, but still it was throwing following error. ../libntp/libntp.a(ntp_crypto_rnd.o): In function ...
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1k views

Nagios - check_ntp_time - Offset Unknown

I have a local NTP server running on the subnet to keep other subnet nodes in sync, without every node syncing with upstream servers. But, while implementing the check_ntp_time plugin for Nagios I am ...
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22 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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40 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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2answers
101 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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1answer
84 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
79 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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2answers
37 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
91 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 ...
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55 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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13k views

Hyper-V Machine drifts time all over, even with NTP

Resolved The problem was Hyper-V on that machine. I removed Hyper-V, installed VMware Server, ran the same VM. Time sync issues went away (< 100ms difference after a day). My setup is like this: ...
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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
145 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 ...
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1answer
15k views

How to change time source from “Local CMOS Clock” to “DC”

In a domain, I want to set DC as time server. To do that I use this command: w32tm /config /manualpeerlist:europe.pool.ntp.org /syncfromflags:manual /reliable:yes /update and w32tm /resync ...
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4answers
11k views

Setting up a local stratum 2 NTP server

I'm trying to setup NTP on a local network that has no (and never will) internet connection. The main priority is that the machines on the network are synced with each other, even if the time they're ...
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2answers
26 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
92 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
20 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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136 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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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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14 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
278 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 ...
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1answer
132 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
84 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
78 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
97 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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53 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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52 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
79 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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2answers
100 views

SES time sync error

My SES setup was running fine for the last 6 months without any issues. All of a sudden it stopped working yesterday and I'm gettinng the infamous time sync error. Naturally I assumed ntpd had ...
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1answer
143 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 ...
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2answers
3k views

NTP local query always times out

I have a CentOS 6.4 server, it does not have any iptable rules, it runs NTP daemon as service using the following configuration: driftfile /var/lib/ntp/drift server 0.pool.ntp.org server ...
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1answer
68 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
48 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 ...
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1answer
2k views

Nagios NTP, discarding peer

We're using nagios *check_ntp_time* for monitoring time on our servers. Unfortunately the service is flapping. And reporting a lot of false-positives. It happens everytime for random server in random ...
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3answers
299 views

How to keep the time on multiple servers in sync

I want a cluster of servers to have the exact same time. All are using UTC time zone. Using NTP currently, i still see they seem to be off by 10-20 miliseconds each. Whats the best way to have them ...
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3answers
1k views

Is there research material on NTP accuracy available?

As far as I know, accuracy of NTP syncronization highly depends on the network. I've seen some numbers from 50 microseconds to a "below one second" over the internet. Well, this is a huge difference. ...
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5answers
13k views

ntpdate -d Server dropped Strata too high

I cannot sync with a NTP source thats coming from an internal router/firewall. Anyone help ? ntppdate -d 192.168.92.82 6 Jun 11:57:30 ntpdate[5011]: ntpdate 4.1.2@1.892 Tue Feb 24 06:32:26 EST ...
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2answers
3k views

Is it viable to use w32tm /stripchart to judge time variance of two Windows hosts from each other? A better way to discover two host's time variance?

Is it viable to use w32tm.exe's option stripchart to judge the time variance of two hosts (within a very small margin of error)? Note that w32tm.exe's stripchart function is separate than the ...
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3answers
1k views

Why doesn't the time match on two Windows Domain Controllers despite resync?

In my domain there are two domain controllers, there is a gap of 3 minutes between their times and than I can find this difference between many clients (it depends on their DC). If I run this ...
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1answer
268 views

Windows Server system time drifts badly on Amazon EC2 instance

We've been using an EC2 micro instance for a little remote monitoring for the past few weeks, and it's bothered me badly how the system time is never accurate; no matter how much fighting I did with ...
2
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3answers
472 views

CentOS VM, NTP synchronization problems

We have three CentOS 5.9 VMs on an ESX3.5 host. Because of the nature of the services we provide it is required that the NTP time is synchronized and the time is correct on all three of them. ...
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3answers
3k views

Do I need to run a NTP server in every VM?

Couldn't the guests somehow inherit the system time of the host ? It seems kind of pointless to run the same daemon to get the same results on the same machine multiple times but I didn't find ...