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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37 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 ...
2
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1answer
22 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", ...
0
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1answer
802 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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1answer
26 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 ...
1
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1answer
37 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 ...
0
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0answers
17 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 ...
0
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0answers
26 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 ...
1
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1answer
44 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 ...
0
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2answers
39 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 ...
1
vote
1answer
51 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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2answers
2k 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 ...
0
votes
1answer
40 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
33 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 ...
2
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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 ...
0
votes
1answer
255 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 ...
3
votes
3answers
209 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 ...
6
votes
3answers
784 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. ...
7
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5answers
10k 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 ...
4
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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 ...
2
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3answers
119 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 ...
0
votes
1answer
72 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
354 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
2k 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 ...
0
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1answer
39 views

Virtual guest: NTP sync with host

Is there any way to get a virtual guest to only query it's current host for NTP? I'm not talking about configuring ntp.conf with the host's IP here either as VLAN's & firewalls may block that ...
2
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1answer
305 views

Real-time clock is wrong (from hours to years), one-time non-monotonic change at boot needed. Can Chrony solve this?

I can't guarantee a sane real-time clock on some machines (the time might be wrong by hours, months or even years). Since I also have intermittent networking, I set up Chrony in the hopes it could fix ...
8
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7answers
3k 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 ...
4
votes
1answer
196 views

Why is the time on my Server 2008 R2 DC wrong? It's syncing to ntp.org, it claims

OK. After a lot of fun with syncing time across my workstations, I got that sorted out. My workstations are now perfectly synced with my Server 2008 R2 Domain Controller (physical server, not ...
0
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0answers
49 views

Signed NTP authentication

Using ansible, I have setup several Signed NTP servers around our network. The servers themselves are Virtual Hosts running on CentOS 6.5. I have the virtual machine guests on each host contact their ...
3
votes
2answers
368 views

Delay NTP Initialisation, Cisco 877W, IOS 12.4(24)T1

I have a Cisco 877W which I'm using for my home ADSL connection (and as a refresher in Cisco IOS). I've got a working config in-place with my PPPoA connection coming online correctly, and VLANs and ...
1
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1answer
53 views

NTP Server in Network Switch

Is it possible to set up a Switch to acts an NTP Server for the devices connected to its VLAN ? If so ,how can I implement it my HP Switch A3600 JG299A. I want to do this because I do not have ...
2
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2answers
142 views

High Jitter in NTP and poll value never goes above 128

I have a lot of servers syncing to the same NTP servers (4). Not every server is in the same LAN. Some are 3 hops away from the NTP servers and some are 6 hops away. On couple of servers I see that ...
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1answer
213 views

Multiple NTP Server Instances on One Server (Linux)

Is it possible to run multiple NTP server instances on the same system? We're using CentOS for our NTP system and want to synchronize specific time depending on what interface the client comes in on. ...
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2answers
81 views

NTP is not updating the time in local machine [closed]

We are having the server in AWS with Amazon linux. By Default it comes with NTP service and we can see the sync. However when someone change the clock or timing using the below command.... date -s ...
0
votes
1answer
77 views

Group Policy for Time Sync = ARP Flood?

I have a Windows Server 2008 R2 domain controller and a bunch of workstations of various versions of Windows - XP SP3, Vista, 7, 8.1. Time sync wasn't working correctly on a few PCs so I followed the ...
5
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4answers
2k views

NTP fudge network source stratum

Is it possible to configure ntpd to fudge the stratum level of a network source? Upon first glance, I thought the fudge directive could accomplish this, however after browsing the ntp.conf(5) man ...
3
votes
1answer
3k views

How can I disable NTP in pfsense?

I am running my pfSense gateway in a ESXi server. right now the server gets its time from the NTP server specified in the general settings section of the WebGUI. I want to disable this so pfSense ...
3
votes
1answer
153 views

Windows NTP Server A Stratum is 2, Windows NTP Server B Stratum is 15

We have a network that is mostly separated from our corporate network. The corporate network uses ntp1.corpaddress.tdl. We have a second server, isolated.corpaddress.tdl. It is getting its NTP time ...
0
votes
1answer
515 views

How to configure a Cisco Catalyst 2960 to synchronize with an NTP server

I would like to synchronize a Cisco Catalyst 2960 series switch with a publicly available NTP server such as time.apple.com. I have reviewed the knowledge base article here: Catalyst 2960 ...
0
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1answer
112 views

Windows server and AWS clock synchronization

I have a Windows 7 computer that communicates with Amazon Web Servers (S3, SES). This server uses windows internet time for clock synchronization time.windows.com. On my linux machines I ran into ...
3
votes
1answer
329 views

Windows NTP server with Linux clients

Has anyone got any experience syncing Linux (specifically Red Hat) to a Windows NTP server? Currently our Windows server is syncing to an stratum 1 server on the internet but the Linux boxes refuse to ...
13
votes
2answers
521 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 ...
0
votes
2answers
159 views

Troubleshooting unwanted NTP Traffic

A domain controller running Windows Server 2012 is sending NTP and NETBIOS traffic to an address that has never been configured as a time provider. The server logs give no indication that any NTP ...
4
votes
2answers
2k 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 ...
4
votes
1answer
267 views

NTP sync time frequently on Windows 7

I have several Win7 64bit configurations - local dev machine, remote server, VPS. I'm running time sensitive tasks on all of them, therefore I need Windows Time service to: Sync Sync well ...
4
votes
3answers
5k views

NtpClient will wait 3473457 minutes (over 6 years!) before it will do a new attempt of DNS resolution, eventid 134

I find the message hilarious and at first I thought it was some joke from an over-active programmer of the MS team, or a hoax. However, the message appears again and again, a couple of times a day: ...
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2answers
2k views

enable/disable ntp service on ubuntu 12.04

Our application runs on Ubuntu 12.04 Precise. On this server, we have both ntpdate and ntp. How to enable and disable the NTP service on-demand? I tried # sudo update-rc.d -f ntp remove/default ...
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0answers
343 views

ntp is not syncing on centos server but gets response from remote server

I have googled for days before asking and I feel like I have tried everything but ntp is still not updating the time of the system automatically. I have left it running for days and still I get the ...
0
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2answers
199 views

Set NTP not to receive time from peers on Ubuntu

In my /etc/ntp.conf, it says By default, exchange time with everybody, but don't allow configuration. restrict -4 default kod notrap nomodify nopeer noquery restrict -6 default kod notrap nomodify ...
1
vote
1answer
120 views

Domain member as ntp server for other (non-domain) network

I am attempting to synchronize the date and time for a number of computers belonging to a non-domain, statically configured network (e.g. computer B in illustration) with a node which is residing in a ...
0
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1answer
69 views

Set a system's time server to itself

I work on a standalone network that has 3 domain controllers all running Server 2008 r2. Two of the servers are physical (DC1 / DC2) and one is virtual (DC3). I want all my systems to refer to DC1 as ...