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20 votes
Accepted

How to synchronize time on ESXi Windows virtual machines within one second?

This is 2018. Windows is capable of keeping servers synchronized within 2 ms or so, as required by MIFID II Regulations. So, your problem is a non-problem. Our sysadmins using windows NTP to sync ...
TomTom's user avatar
  • 51.9k
15 votes
Accepted

How to set up local ntp server without internet access on ubuntu?

Don't do this. Seriously. Just don't. People keep coming up with the idea that NTP is designed to allow a bunch of machines all to have the same time. It isn't. It's designed, quite carefully, to ...
MadHatter's user avatar
  • 80.7k
12 votes

Sync ntp immediately at boot with undiciplined clock

You can use the -g parameter. From the manpage: -g Normally, ntpd exits with a message to the system log if the offset exceeds the panic threshold, which is 1000 s by default. This option allows the ...
basekat's user avatar
  • 456
11 votes
Accepted

Ubuntu 20.04 time sync problems and possibly incorrect status information

The timedatectl command reports that NTP is in use when either chronyd or systemd-timesyncd is enabled and running. Both of these are lightweight NTP clients suitable for most servers and workstations....
Michael Hampton's user avatar
9 votes

Ntpd on local network - Preventing clock drift causing high offsets

A driftfile records the frequency of the local clock, and is a good thing to have to accurately discipline it. Ubuntu /etc/ntp.conf has a driftfile by default. Appending iburst to the server line ...
John Mahowald's user avatar
8 votes
Accepted

Chrony doesn't appear to be syncing with the servers I've specified

The servers you've specified: server 0.us.pool.ntp.org server 1.us.pool.ntp.org server 2.us.pool.ntp.org server 3.us.pool.ntp.org are, as the names suggest, part of the NTP Pool Project. When you ...
Michael Hampton's user avatar
8 votes
Accepted

w32time in domain polling from wrong Domain Controller

From the MS Documentation I can see that computers in a domain should get their time from the PDC domain controller Not an accurate statement. Domain members need not sync time with the PDCe ...
Ryan Ries's user avatar
  • 55.9k
8 votes
Accepted

Allow Active Directory users to disable datetime sync

As pointed out by @MDMarra, using a VM is a great way to go because blocking time synchronization can cause significant problems for authentication, TLS certificate validity, etc. However, for true ...
Sam Erde's user avatar
  • 3,469
7 votes

Allow Active Directory users to disable datetime sync

You really don't want to do this. Time sync is critical to Kerberos functioning properly. Unless you want authentication failures, you'll leave the system clocks where they are. Perhaps a non-domain ...
MDMarra's user avatar
  • 101k
7 votes
Accepted

no internet time tab on domain controller, Windows Server 2016

However, my computer is a domain controller which should provide the time for clients. Could it be that my domain controller is anyhow configured as both at a time, server and client? The Domain ...
joeqwerty's user avatar
  • 111k
6 votes

Turn OFF NTPD immediatly synchronization

By default, ntpd will step (instead of slew) the time if the offset is greater than 128ms. You can avoid that with the -x command line option, but beware: Correcting one second of offset will take ...
Sven's user avatar
  • 99.6k
6 votes

Incorrect Ubuntu server time

How to keep accurate time on Ubuntu continuously? By enabling the ntpd service and running it continuously. I synchronized it using sudo ntpdate -s time.nist.gov few months ago but it jumped ...
HBruijn's user avatar
  • 80.3k
6 votes

Incorrect Ubuntu server time

Unfortunately Ubuntu hasn't added the disclaimer from NTP.org's ntp-4.2.*\html\ntpdate.html manual to Ubuntu's ntpdate(8) manpage, like for example FreeBSD has: ntpdate - set the date and time via ...
Esa Jokinen's user avatar
  • 49.8k
6 votes
Accepted

hwclock: Cannot access the Hardware Clock via any known method

The problem seems to be connected to clocksource, check available_clocksource: $ cat /sys/devices/system/clocksource/clocksource0/available_clocksource tsc hpet acpi_pm Based on answer to "What does ...
Tombart's user avatar
  • 2,213
6 votes
Accepted

Why is my internal clock always 1.3 seconds off?

Turns out w32time simply sucks. Microsoft admitted that w32time cannot reliably maintain sync time to the range of 1 to 2 seconds. Great software guys... I installed a different implementation ...
Grunzwanzling's user avatar
6 votes

How to synchronize time on ESXi Windows virtual machines within one second?

Is it correct for us to ask for "within second" or we need to ditch Quartz entirely? There are lots of very good reasons for various application stacks to need tight time control and what Quartz ...
Chopper3's user avatar
  • 102k
6 votes

Sync ntp immediately at boot with undiciplined clock

In addition to the -g flag described above, you should add iburst to the server line on the clients. This will cause them to sync more quickly to the server. However, you can't expect your server ...
Paul Gear's user avatar
  • 4,507
5 votes

System time is off by up to hundreds of milliseconds despite NTP sync before boot

I do not have numbers to produce, but it seems probable that the interface used to set the clock at boot only has precision down to the second. You do not state your OS, but on all Unix-like systems ...
Law29's user avatar
  • 3,577
5 votes

change time grayed out in windows server 2016

I had the same problem and the issue wasn't related to policy. Only changing it in the Local Server section of the Server Manager worked. See this article: https://www.dtonias.com/set-time-date-...
user502591's user avatar
5 votes

Ntpd on local network - Preventing clock drift causing high offsets

Your lack of a relation between your NTP server's clock time and the real-world UTC time could be the root of your problem. If your NTP server does not have multiple real-world sources (regardless of ...
Paul Gear's user avatar
  • 4,507
5 votes
Accepted

Windows Server Time-Service jumps into the future and (partially) back

UPDATE: Ars Technica has written an article on this problematic feature: https://arstechnica.com/security/2023/08/windows-feature-that-resets-system-clocks-based-on-random-data-is-wreaking-havoc/ TL;...
simendsjo's user avatar
  • 354
4 votes
Accepted

Incorrect Ubuntu server time

Install ntp package sudo apt-get install ntp Edit /etc/ntp.conf for your neighbor ntp server sudo vi +/^server /etc/ntp.conf Reload ntp configuration sudo service ntp reload Check time sync status ...
minish's user avatar
  • 656
4 votes
Accepted

Getting HTTP response with date before request date. Is that right?

Many servers and clients do not use NTP to synchronize their time to standard time. The response header should contain a timestamp from the server. Time differences of seconds are common, and it is ...
BillThor's user avatar
  • 28k
4 votes
Accepted

Unable to synchronize date by NTP on Debian 9

Hyper-V includes system clock synchronization service that is enabled by default; in other words, your ntpd or systemd-timesyncd is fighting with Hyper-V syncing the time of the guest VM to the time ...
telcoM's user avatar
  • 4,618
4 votes

How to synchronize time on ESXi Windows virtual machines within one second?

https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/support-boundary High Accuracy support for Windows 8.1 and 2012 R2 (or Prior) Earlier versions of Windows (Prior to ...
Greg Askew's user avatar
  • 36.8k
4 votes
Accepted

What time zone does windows event logs show

Windows stores the time stamps for events from the event log in UTC time - regardless of the currently configured time zone of the computer. When viewing the event however, the timestamp is converted ...
Lucky Luke's user avatar
  • 1,654
3 votes

ntp.conf: Is it reasonable to rely on default server list, exposed in CentOS?

The short version: it is probably safe. The longer version: the behaviour you are seeing is completely normal and expected. The NTP pool is a dynamic pool which will likely change each time the DNS ...
Paul Gear's user avatar
  • 4,507
3 votes
Accepted

chrony and gpsd: socket or PPS connection

First, pps is NOT available via USB. You need to use a direct connection. USB is polled and thus cannot provide an accurate enough signal. I learned this trying to set up some Windows boxes at work....
robin's user avatar
  • 46
3 votes

How to keep time on resumed KVM guest with libvirt?

libvirt supports guest time sync since 2015. On Debian Stretch and later look for option SYNC_TIME in /etc/default/libvirt-guests: # If non-zero, try to sync guest time on domain resume. Be aware, ...
Jakob's user avatar
  • 31
3 votes

How do I update a CentOS server's time from an authoritative time server?

For centos 7.x installation: yum install ntp systemctl enable ntpd initial sync, with: ntpdate pool.ntp.org start the daemon with: systemctl start ntpd
Ben's user avatar
  • 131

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