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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3answers
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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 ...
4
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2answers
18k views

Active Directory Time Synchronisation - Time-Service Event ID 50

I have an Active Directory domain with two DCs. The first DC in the forest/domain is Server 2012, the second is 2008 R2. The first DC holds the PDC Emulator role. I sporadically receive a warning ...
12
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4answers
7k views

What are the limits of running NTP servers in virtual machines?

I want to set up several Stratum 2 time servers on my local network. Virtual machines would certainly be a cheaper way to do this than buying three 1U servers. What limitations would doing so impose? ...
3
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2answers
334 views

periodically overridding NTP for simulation purposes

I have this situation: NTP is used to sync time on a set of Windows 7 and Server 2008 machines. Nothing out of the ordinary about this. periodically on this system, the time needs to be changed for ...
3
votes
2answers
8k views

Domain Controller time is 7 minutes fast

I have a Server 2008 R2 domain controller running in VM on Hyper-V that is 7 minutes fast which I need to fix. I understand that this maybe down to the DC running in VM's. What I would like to know ...
19
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10answers
20k views

Compare NTPD and ntpdate

What are the pros and cons between these two ways to synchronize your server? It seems to me that your server would probably not drift more than 1 second every day, so ntpdate on a crontab would be ...
9
votes
4answers
29k views

How to set a frequent period for NTP client to sync with the NTP server

I've setup an NTP client for my DC to sync time with time.windows.com but I want it to query the NTP server at least twice a day. I made all the changes via the registry, is there a period registry I ...
30
votes
12answers
15k views

Is anyone using GPS for time sync?

I've come across a handful of GPS NTP servers, as well as some inexpensive solutions using off-the-shelf receivers and software. Right now I'm just using NTP with a list of servers over the Internet. ...
8
votes
3answers
541 views

Best choice for NTP client configuration

Lets see if someone can throw a bit of light on this subject.. I'm making a server installation in the next days. My client wants to deploy a Hortonworks HDP with 2 servers as master servers and 5 ...
8
votes
7answers
15k 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: ...
1
vote
3answers
2k views

Increasing the accuracy of windows 2003 NTP time sync

Hi using w32tm or some other service (NTP W32Time) is there away to increase the accuracy of windows time to sync at-least every 1sec? Whats setup; windows 2003 AD environment with a few servers and ...
8
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7answers
6k views

Local or public NTP servers?

For a relatively large network (thousands of hosts) - what are the arguments for and against running a locally managed (pool of) NTP server(s) (perhaps periodically set via some public NTP server) and ...
1
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2answers
2k views

Setting NTP on Windows 2008 Domain

Our Computers are out by a couple of minutes on the network. I have checked the registry on a computer and found that the type is NT5DS which I believe that it is getting the time from our Domain ...
6
votes
3answers
4k views

Using NTP to sync a group of linux servers to a common time source

I have 20 or so linux servers and I want to sync all of their clocks to a single NTP server, which is in the same rack and switch as my servers. Nothing is virtualized. Our admins are having trouble ...
13
votes
2answers
6k views

Why does ntpd listen on so many ports/addresses?

I’ve noticed this for a while, and it’s never made any sense to me: Why does ntpd need to listen on so many addresses? For example, a Debian machine: $ netstat Proto Local Address Foreign Address ...
11
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7answers
80k views

Why is ntpd not updating the time on my server?

I have ntpd running on my server. It's all the default settings, except I commented out its ability to be a server to other machines: # restrict -4 default kod notrap nomodify nopeer noquery ...
5
votes
3answers
3k views

SNTP, why do you mock me?

--- SOLVED SEE EDIT 5 --- My w2k3 pdc is configured as an authoritative time server. Other servers on the domain are able to sync with it if I manually specify it in the peer list. By if I try to ...
3
votes
1answer
9k 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 ...
9
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9answers
7k views

Time drift

How do you deal with server time drift?
8
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3answers
5k 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. ...
6
votes
2answers
362 views

Time synchronization in an heterogeneous environment

In a mixed environment, where machines can be running under Windows (most), Linux (a few), sometimes Android ... what is the best solution to have time synchronization with an accuracy close to ...
6
votes
2answers
3k views

What is a realistic average time difference between servers in the same LAN?

Until recently, we had at work a small cluster of about 20 small Windows servers (which have now all been virtualized). They were all configured to synchronize with the local time server. It was on an ...
6
votes
6answers
13k views

Domain Controller time is incorrect

I have a domain controller running in VM on Hyper-V, the time seems to be steadily getting faster, over the X-mas period it's 5 faster, which seems odd! I know how to change the time and I belive we ...
4
votes
4answers
770 views

Make Windows Server 2008 periodically update internet NTP

I have read a bunch of posts and other information on the internet and I have yet to come across the solution to this question. On a windows network, all the computers sync up with the domain ...
4
votes
4answers
23k views

Problem synchronizing server time with ntpd

I am trying to ntp sync one machine with another. both runs Debian lenny, and I installed the ntp package in both. I configured the server to synchronize with an external machine by putting server ...
4
votes
3answers
14k views

DHCP Options for Network Time Server

It looks like there are two options for providing network time settings to a DHCP client; option 004 and option 042. The description for 004 is "Time Server", while 042 specifies NTP. Is there a ...
3
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5answers
990 views

Time synchronization and scheduled tasks

If NTP runs at 10:59:55, and fixes the time to 11:00:13, does chron run the 11:00:00, and *:00:00 tasks, or are they skipped? Alternately, if NTP runs at 11:00:00 and fixes the time to 10:59:48, do ...
2
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2answers
18k views

Time not propagating to machines on Windows domain

We have a two-domain Active Directory forest: ourcompany.com at the root, and prod.ourcompany.com for production servers. Time is propagating properly through the root domain, but servers in the child ...
1
vote
1answer
186 views

Setting up NTP on 2 Linux boxes and one OpenBSD box

I have been tasked with getting an NTP client working on two Linux machines and an OpenBSD machine. The machines are arranged like this: NTPServer / \ / \ L1 L2 ...
1
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2answers
1k views

RHEL 5 Hyper-V Guest - Cannot sync with NTP after kernel upgrade

I'm running a RHEL 5 (64 bit) guest on Microsoft Hyper-V. I've always had trouble with the clock getting way ahead of itself, which I was able to solve previously by adding divider=10 ...
0
votes
1answer
38 views

Where can I see ntpd working status (log or message)

In my server the ntpd service is started but it does not seem to work. I can find nothing according to this ( Where are the ntpd log file located, and how can we configure the ntpd log file path? ) ...
0
votes
3answers
1k views

NTP time sync not working in a DOMU Centos 5.5 server

I have a Xen Centos 5.5 server with ntpd working in virtual server. NTP time sync seems not working. I have disabled any firewall. my grep -i ntpd /var/log/messages output: Apr 1 16:15:47 ...
13
votes
2answers
660 views

What can be done to improve time synchronization on networks with sporadic internet access?

I'm looking for advice setting up time servers for a very non-typical network. I support many closed networks that have occasional access to the internet. A network would get access most days for a ...
7
votes
1answer
1k views

How well will ntpd work when the latency is highly variable?

I have an application where we are using some non-standard networking equipment (cannot be changed) that goes into a dormant state between traffic bursts. The network latency is very high for the ...
5
votes
4answers
5k views

openwrt: Use rdate with NTP servers?

I've noticed that some embedded devices (such as OpenWRT, which runs on Busybox) use rdate to set the system time, instead of NTP. Rdate is an older time protocol, and I'm having trouble finding any ...
4
votes
3answers
1k views

winter and summer time switch without a break in the timeline

Does anybody know if there is a possibility to switch from summer- to wintertime without an interruption in the timeline. I have an application that logs transactions with a timestamp. The problem ...
3
votes
2answers
987 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 ...
3
votes
2answers
3k views

Fake SNTP server for testing

I want to setup an SNTP server for testing purposes that can be set to any arbitrary value (for example testing DST behaviour of the device under test) serve only on eth1 on my RedHat Enterprise ...
2
votes
2answers
4k views

Both my ntp servers are marked as falsetickers in the status [closed]

I have a linux box, set up with two ntp servers to sync. This box in case, was extremely out of sync (61 seconds) before it was forced sync. The following outputs are 1 hour after this sync. When ...
2
votes
1answer
689 views

Time issues on the Network — How to find the Root Cause

A number of application servers started erroring out in my domain. Troubleshooting led me to a missconfiguration of NTP. I fixed the issue, but I don't know how the issue arose in the first place. ...
2
votes
2answers
6k views

Cisco ASA5505 won't sync with NTP

Today I noticed that the clock my Cisco ASA 5505 firewall was running about 15 minutes late, which surprised me since I've set up the NTP client. My two NTP servers 10.10.0.1 and 10.10.0.2 are ...
2
votes
5answers
5k views

Does CentOS 5.4 properly handle leap seconds?

Apparently the IERS have announced a leap second due at midnight, June 30th this year. Is CentOS/RHEL 5.4 properly updated to support/transition along with updated NTP systems? I was under the ...
2
votes
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 ...
2
votes
2answers
2k views

Synchronizing time with only one NTP server

I have a linux machine on a network where the machine only has access to exactly one NTP server. After the time synchronization the status looks like this: [root@test ~]# ntpq -p remote ...
1
vote
2answers
949 views

ntpdate wrong date

Hi all I have an ubuntu8 server where I have problems with date. My current date (Europe/Rome) is 9:35 If I do date print me 11:12:34 I have seen my ntp.conf is: server 0.ubuntu.pool.ntp.org ...
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2answers
1k views

How often does openntpd update the time?

Neither the openntpd nor the ntpd.conf manpage have this information.
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3answers
1k views

Building a local time server

I am trying to install a time server on a local Ubuntu machine, so other servers in my network would sync with it. We have decided to install our own time server, rather than letting each server ...
0
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1answer
60 views

How can I synchronize system time with a NTP server continuously?

Is there a linux service that can synchronize system time with a NTP server with a given interval, such as 1 minute, 1 hour or 1 day ? Is it a good practice to run utpdate in a cron tab? e.g. */10 * ...
0
votes
1answer
2k views

Using NTPD on OpenBSD to get time from Linux using portforwarding

This is a rehash of another question, now that I understand things a bit better. I have the following network set up: NTP 10.21.3.169 | \______________ | \ ...
0
votes
1answer
396 views

Disconnect Local Clock from Domain Controller Clock

How can I disconnect my workstation clock from the domain controller? In other words, I do not want them synchronized.