Saucepan

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====== Public NTP Servers ======

  * There is a dedicated page to [[ntp:ntp|general NTP]].
  * There is a dedicated page to [[infoblox:ntp_on_infoblox|Infoblox NTP]].

===== pool.ntp.org =====

**DO NOT** use burst or iburst against public NTP servers unless they are announced they accept it (e.g. don't use it against *.ntp.org servers). More details [[ntp:ntp#burst_and_iburst|here]].

**DO NOT** configure your system to use leap-smearing NTP servers as well as non-leap-smearing NTP servers at the same time. e.g. do not combine Google NTP with Cloudflare NTP. See [[ntp_pools#leap_smearing|here]].

**REMEMBER** Don't be a twat. Don't configure your entire network to use these servers. You should use only a very small handful of NTP servers on your network to sync out and then get your entire network to use your internal NTP servers. Don't contribute to overloading public NTP servers.

In most cases it's best to use pool.ntp.org to find an NTP server (or 0.pool.ntp.org, 1.pool.ntp.org, etc if you need multiple server names). The system will try finding the closest available servers for you. ([[https://www.ntppool.org/zone/@|source]])

The number of active service in the geographic regions can be found [[https://www.ntppool.org/zone/@|here]].


For the following list of NTP pools, you can use the following and/or prefix 0. or 1. or 2. or 3. to the FQDN
  * pool.ntp.org
  * africa.pool.ntp.org (54)
  * asia.pool.ntp.org (282)
  * europe.pool.ntp.org (2784)
  * north-america.pool.ntp.org (934)
  * oceania.pool.ntp.org (126)
  * south-america.pool.ntp.org (58)
  * <country code>.pool.ntp.org (e.g. uk.pool.ntp.org)
  * <distribution>.pool.ntp.org (e.g. ubuntu.pool.ntp.org. **NOTE** for these you need to prefix 0. or 1. or 2. or 3. to the FQDN)

===== Leap Smearing =====

**DO NOT** configure your system to use leap-smearing NTP servers as well as non-leap-smearing NTP servers at the same time. e.g. do not combine Google NTP with Cloudflare NTP as they [[https://developers.cloudflare.com/time-services/ntp/usage|do not implement leap smearing]]. Smearing is used by Google, AWS, and Facebook NTP servers but not Cloudflare.

More information on Google's NTP offering can be found [[https://developers.google.com/time/faq|here]]. Google 'smear' a leap second over the course of the hour either side of the leap second. Do not mix NTP servers that 'smear' and NTP servers that do not 'smear'. Google uses its own NTP servers for its public DNS servers. If you cannot configure multiple servers, ''time.google.com'' will automatically select an appropriate Google server nearby.

Infoblox NIOS uses leap smearing. ([[https://docs.infoblox.com/display/NAG8/Using+NTP+for+Time+Settings|source]])
===== NTP Servers =====
In addition to pool.ntp.org, there are several other publicly accessible NTP servers (some of which also appear in pool.ntp.org).

**DO NOT** use burst or iburst against public NTP servers unless they are announced they accept it (e.g. don't use it against *.ntp.org servers). More details [[ntp#burst_and_iburst|here]].

**DO NOT** configure your system to use leap-smearing NTP servers as well as non-leap-smearing NTP servers at the same time. e.g. do not combine Google NTP with Cloudflare NTP. See [[ntp_pools#leap_smearing|here]].


For your time source list, also consider using one or two from  and something appropriate (Top Public Time Servers) from .


Lists of Stratum 1 servers are here:
  * [[http://tf.nist.gov/tf-cgi/servers.cgi|NIST]]
  * [[http://support.ntp.org/bin/view/Servers/StratumOneTimeServers|ntp.org]]

Useful GitHub list [[https://gist.github.com/mutin-sa/eea1c396b1e610a2da1e5550d94b0453|here]].

Examples are:
  * ntp0.ja.net (Stratum 1)
  * ntp1.npl.co.uk (Stratum 2)
  * time.cloudflare.com (Stratum 3)

Cloudflare's service provides NTP services over their anycast network of over 180 locations worldwide. Cloudflare's NTP server already support NTS. If you have an NTS client you can point it at time.cloudflare.com:1234

More information on [[https://gist.github.com/n1zyy/d58555b0d6ffe5d935bb7c0ccf19eada|Apple time]].

^Operator ^ Server FQDN ^ Server IP ^ Stratum ^ RefID ^ Source Type or FQDN ^ Delay ^
| Cloudflare | time.cloudflare.com | 162.159.200.1 | 3 | 10.21.8.19 | Internal Cloudflare? | 13.080 |
| Cloudflare | time.cloudflare.com | 162.159.200.123 | 3 | 10.21.8.19 | Internal Cloudflare? | 13.896 |
| Microsoft | time.windows.com | 51.145.123.29 | 3 | 25.66.230.5 | Internal Microsoft? | 13.896 |
| Zen Internet | ntp0.zen.co.uk | 212.23.8.6 | 2 | 195.66.241.3 | ntp1.linx.net | 11.642 |
| Zen Internet | ntp1.zen.co.uk | 212.23.10.129 | 2 | 85.199.214.99 | server1.quickdrivingtestcancellations.net | 16.948 |
| National Physics Laboratory | ntp1.npl.co.uk | 139.143.5.30 | 2 | 139.143.45.169 | ? | 16.457 |
| National Physics Laboratory | ntp2.npl.co.uk | 139.143.5.31 | 2 | 139.143.45.169 | ? | 17.329 |
| Manchester University | ntp2a.mcc.ac.uk | 130.88.202.49 | 2 | 193.62.22.66 | ntp0.ja.net | 22.581 |
| Manchester University | ntp2b.mcc.ac.uk | 130.88.203.13 | 2 | 130.88.203.13 | ntp0.ja.net | 22.282 |
| Manchester University | ntp2c.mcc.ac.uk | 130.88.200.6 | 2 | 193.62.22.66 | ntp0.ja.net | 22.135 |
| Manchester University | ntp2d.mcc.ac.uk | 130.88.212.143 | 2 | 193.62.22.74 | ntp1.ja.net | 22.771 |
| JANET, Harwell (London) | ntp0.ja.net | 193.62.22.66 | 1 | .MSF. | MSF Radio Clock Receiver | 15.981 |
| JANET, Harwell (Swindon) | ntp1.ja.net | 193.62.22.74 | 1 | .MRS. | N/A | 26.042 |
| JANET, Harwell (Manchester) | ntp2.ja.net | 193.62.22.98 | 2 | 193.62.22.74 | ntp1.ja.net | 22.849 |
| JANET, Harwell (Edinburgh) | ntp3.ja.net | 193.62.22.90 | 1 | .PPS. | N/A | 26.305 |
| JANET, Harwell (Harwell) | ntp4.ja.net | 193.62.22.82 | 1 | .DCFa. | DCF77 | 17.528 |
| Google | time.google.com | time1-time4  | 1 |  |  |  |
| Google | time1.google.com | 216.239.35.0  | 1 | .GOOG. | N/A | 20.393 |
| Google | time2.google.com | 216.239.35.4 | 1 | .GOOG. | N/A | 20.399 |
| Google | time3.google.com | 216.239.35.8 | 1 | .GOOG. | N/A | 20.514 |
| Google | time4.google.com | 216.239.35.12 | 1 | .GOOG. | N/A | 22.899 |
| Facebook | time.facebook.com | time1-time5  | 1 |  |  |  |
| Facebook | time1.facebook.com | 129.134.28.123 | 1 | .FB... | N/A | 25.595 |
| Facebook | time2.facebook.com | 129.134.29.123 | 1 | .FB... | N/A | 16.803 |
| Facebook | time3.facebook.com | 129.134.25.123 | 1 | .FB... | N/A | 12.037 |
| Facebook | time4.facebook.com | 129.134.26.123 | 1 | .FB... | N/A | 18.341 |
| Facebook | time5.facebook.com | 129.134.27.123 | 1 | .FB... | N/A | 16.546 |
| AWS | ? | 169.254.169.123 | ? | ? | ? | ? |
| Apple | time.apple.com | 17.253.108.253 (and others)  | 1 | .SHM. |  | 17.343 |
| Apple | time.euro.apple.com | 17.253.34.125 (and others) | 1 | .SHM. |  |  9.889 |
| Leo Bodnar Electronics | ntp1.leontp.com | 51.155.16.62 | 1 | .GPS. | N/A | 36.932 |
| Leo Bodnar Electronics | ntp5.leontp.com | 85.199.214.98 | 1 | .GPS. | N/A | 16.523 |
| Leo Bodnar Electronics | ntp6.leontp.com | 85.199.214.99  | 1 | .GPS. | N/A | 15.949 |
| Leo Bodnar Electronics | ntp7.leontp.com | 85.199.214.100 | 1 | .GPS. | N/A | 16.002 |
| Leo Bodnar Electronics | ntp8.leontp.com | 85.199.214.101 | 1 | .GPS. | N/A | 16.595 |
| Leo Bodnar Electronics | ntp9.leontp.com | 85.199.214.102 | 1 | .GPS. | N/A | 15.965 |
| Xentex IT Solutions | ntp.xtx.cloud | 81.133.66.177 | 1 | .PPS. | N/A | 24.301 |
| Nest | time.nest.com | 216.239.35.0 | 1 | .GOOG. | N/A | 11.6 |