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A list of the Simple Network Time Protocol (SNTP) time servers that are available on the Internet

Article ID: 262680 - View products that this article applies to.

This article was previously published under Q262680

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SUMMARY

This article describes the Simple Network Time Protocol (SNTP) time servers that are available on the Internet.

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There are two levels, or tiers, of Network Time Protocol (NTP) time servers that are available on the Internet. The NTP is defined in Request for Comments (RFC) 1305.

The first-level time servers are primarily intended to act as source time servers for second-level time servers. The first-level time servers may also be capable of providing mission-critical time services. Some first-level time servers may have a restricted access policy.

Second-level time servers are intended for general SNTP time service needs. Second-level time servers usually enable public access. It is recommended that you use second-level time servers for normal SNTP time server configuration because they are usually located on a closer network that can produce faster updates.

It is recommended that you research any time server selection to ensure that it can meet your specific time server requirements.

Time server list

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For the list of stratum one time servers, visit the following Web site:
http://support.ntp.org/bin/view/Servers/StratumOneTimeServers
(https://support.ntp.org/bin/view/Servers/StratumOneTimeServers)
For the list of stratum two time servers, visit the following Web site:
https://support.ntp.org/bin/view/Servers/StratumTwoTimeServers
(https://support.ntp.org/bin/view/Servers/StratumTwoTimeServers)
For the list of NTP Pool Servers, visit one of the following Web sites:
http://support.ntp.org/bin/view/Servers/NTPPoolServers
(https://support.ntp.org/bin/view/Servers/NTPPoolServers)

http://www.pool.ntp.org
(http://www.pool.ntp.org)

Microsoft does not maintain the list of time servers or recommend one time server over the other one. These links are for your reference and research to select the time server(s) appropriate for your configuration. Microsoft does recommend that workgroup computers sync from the Microsoft NTP server (time.windows.com). If another time source is desired, we recommend that you use one of the Stratum 2 Time Servers. To find the Stratum 2 Time Servers that are available, visit the following Web site:

https://support.ntp.org/bin/view/Servers/StratumTwoTimeServers

(https://support.ntp.org/bin/view/Servers/StratumTwoTimeServers)

Note Please read the "Rules Of Engagement" before using the Stratum Two Time Servers list. To read the "Rules of Engagement," visit the following Web site:

http://support.ntp.org/bin/view/Servers/RulesOfEngagement

(https://support.ntp.org/bin/view/Servers/RulesOfEngagement)

Domain joined member computers and application servers should be configured to synchronize time by using the domain hierarchy as described in the Domain Hierarchy-Based Synchronization topic at the following Microsoft TechNet Web site:

http://technet.microsoft.com/en-us/library/cc773013(WS.10).aspx

(http://technet.microsoft.com/en-us/library/cc773013(WS.10).aspx)

To synchronize non-domain-joined (workgroup) workstations or servers, visit the following Microsoft TechNet Web site:

http://technet.microsoft.com/en-us/library/cc757721(WS.10).aspx

(http://technet.microsoft.com/en-us/library/cc757721(WS.10).aspx)

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REFERENCES

For more information about the use of time services in Windows Server and Windows NT, click the following article numbers to view the articles in the Microsoft Knowledge Base:

888794

(http://support.microsoft.com/kb/888794/ )

Considerations when hosting Active Directory domain controller in virtual hosting environments

243574

(http://support.microsoft.com/kb/243574/ )

"Could Not Locate a Time Server" After Setting SNTP Time Server Using NET TIME Command

216734

(http://support.microsoft.com/kb/216734/ )

How to configure an authoritative time server in Windows 2000

224799

(http://support.microsoft.com/kb/224799/ )

Basic Operation of the Windows Time Service

951531

(http://support.microsoft.com/kb/951531/ )

The W32Time service does not synchronize the CMOS clock time to the Internet time on a Windows XP or Windows Server 2003-based computer after the W32Time service stops

875495

(http://support.microsoft.com/kb/875495/ )

How to detect and recover from a USN rollback in Windows Server 2003

939322

(http://support.microsoft.com/kb/939322/ )

Support boundary to configure the Windows Time service for high accuracy environments

897615

(http://support.microsoft.com/kb/897615/ )

Support policy for Microsoft software running in non-Microsoft hardware virtualization software

289668

(http://support.microsoft.com/kb/289668/ )

Advancing time on production computers and the effect on Active Directory and FRS