Server Fault Stack Exchange
Server Fault Stack Exchange

Questions tagged [ntp]

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

717 questions
362
votes
5 answers

Anyone else experiencing high rates of Linux server crashes during a leap second day?

*NOTE: if your server still has issues due to confused kernels, and you can't reboot - the simplest solution proposed with gnu date installed on your system is: date -s now. This will reset the kernel's internal "time_was_set" variable and fix the…
Bron Gondwana
  • 1,738
  • 3
  • 12
  • 15
42
votes
4 answers

Windows Server unable to synchronize NTP time reliably

Why does Windows Server (2008, in this case, but I've seen the same problem in 2003) seem to have problem synchronizing time? I've seen this error in my System log across a variety of servers: The time service has not synchronized the system time…
Jeff Atwood
  • 13,104
  • 20
  • 75
  • 92
37
votes
12 answers

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. What is the advantage to using GPS instead…
user640
34
votes
4 answers

How can I compare an ntp server's time to my server's time?

I have ntpd running on a box. I want to see how the time on the box compares to the time retrieved from ntp.ubuntu.com. Is there an easy way to do this?
John Bachir
  • 2,364
  • 7
  • 29
  • 37
32
votes
4 answers

Force systemd timesyncd to sync time with NTP server immediately

I've configured systemd timesyncd to get it's time from a NTP server: /etc/systemd/timesyncd.conf > NTP=ca.pool.ntp.org systemctl restart systemd-timesyncd.service timedatectl set-ntp true The status is the following: $ timedatectl…
manifestor
  • 6,079
  • 7
  • 27
  • 39
28
votes
3 answers

NTP is running, system clock still not in time - what gives?

A Debian Stable (5.0.3) server is running ntpd, and connected to the internet. Still, the system clock is about 5 minutes wrong. $ /etc/init.d/ntp status NTP server is running.. Relevant parts (I think) of /etc/ntp.conf: driftfile…
Jonik
  • 2,961
  • 4
  • 38
  • 48
27
votes
3 answers

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 risks. I have a production Postgres 9.3 server…
vastlysuperiorman
  • 596
  • 6
  • 17
26
votes
4 answers

What is NTP dispersion and how do I control it?

We roll out Ubuntu 14.04 servers on isolated networks, running ntpd 4.2.6p5, configured to use multiple NTP servers as provided by customers (no access to pool.ntp.org). Our dumb terminal client devices run an old version of BusyBox (1.00-rc2) and…
Jeff
  • 363
  • 1
  • 3
  • 6
24
votes
9 answers

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 …
John Bachir
  • 2,364
  • 7
  • 29
  • 37
23
votes
10 answers

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 ok. But I heard you could use redundant NTP servers…
Unknown
  • 1,685
  • 6
  • 20
  • 27
22
votes
6 answers

Things to consider when running public NTP servers

So, it recently dawned on me that since I have 3 GPS clocks in my network, I could, technically, give back a little and serve time to the rest of the world. So far I've not quite seen any downsides with this ideas, but I have the following…
Stuggi
  • 3,506
  • 4
  • 19
  • 36
22
votes
8 answers

Should servers have their timezone set to GMT/UTC?

This may not be a big deal for smaller shops that only have one or a few site, but for larger organizations this is something I'm curious about. What are the pros and cons have having all/most of your server in UTC? It would certainly help in…
user57244
21
votes
4 answers

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. I believe, accuracy dependence is a great…
akalenuk
  • 543
  • 2
  • 6
  • 17
19
votes
3 answers

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 reason to use one or the other, or is it just vendor…
TimM
  • 293
  • 1
  • 3
  • 6
19
votes
4 answers

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 anything related to time when reading KVM or Xen…
zimbatm
  • 453
  • 1
  • 4
  • 7
1
2 3
…
47 48