• There is a dedicated page to general NTP.
• There is a dedicated page to Infoblox NTP.

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 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 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. (source)

The number of active service in the geographic regions can be found 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)

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 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 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. (source)

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 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 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:

• NIST
• ntp.org

Useful GitHub list 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 Apple time.