{"id":2745,"date":"2015-08-13T00:48:16","date_gmt":"2015-08-12T20:48:16","guid":{"rendered":"https:\/\/rakhesh.com\/?p=2745"},"modified":"2015-08-15T15:06:37","modified_gmt":"2015-08-15T11:06:37","slug":"brief-notes-on-windows-time","status":"publish","type":"post","link":"https:\/\/rakhesh.com\/windows\/brief-notes-on-windows-time\/","title":{"rendered":"Brief notes on Windows Time"},"content":{"rendered":"<p>The <code>w32time<\/code> service provides time for Windows. Since Windows XP NTP (Network Time Protocol) is supported. Prior to that it was only SNTP (Simple NTP).<\/p>\n<p>Non domain joined computers (including servers) <a href=\"https:\/\/support.microsoft.com\/en-us\/kb\/939322\" target=\"_blank\">use SNTP<\/a>.<\/p>\n<p><a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/cc773263%28WS.10%29.aspx\" target=\"_blank\">This<\/a> is a good article that explains the Windows Time service and its configurations. Covers both registry keys and GPOs. <a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/cc773013%28WS.10%29.aspx\" target=\"_blank\">This<\/a> is another good article that goes into even more detail.<\/p>\n<p>Any Windows machine can be set up to sync time in one of four ways: (1) no syncing! (2) sync from specified NTP servers (3) sync via<a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/cc773013%28WS.10%29.aspx\" target=\"_blank\"> domain hierarchy<\/a> (i.e. members sync from a DC in the domain; DCs sync from PDC of the parent domain\/ forest root domain) (4) use either of the above (i.e. NTP and domain hierarchy). Default mechanism on domain joined computers is domain hierarchy (the setting is called <code>NT5DS<\/code>). Stand-alone machines have the default as <code>NTP<\/code> servers (the setting is called NTP; the default server is time.windows.com though you can change it (and probably <a href=\"http:\/\/support.ntp.org\/bin\/view\/Support\/WindowsTimeService\" target=\"_blank\">recommended that you change it?<\/a>)).<\/p>\n<p>For machines that are off and on the domain &#8211; e.g. laptops &#8211; it is better to set their time sync mechanism as any. They needn&#8217;t always have contact with the DC to sync time.<\/p>\n<p>When specifying NTP time servers you also specify flags. Check <a href=\"http:\/\/blogs.msdn.com\/b\/w32time\/archive\/2008\/02\/26\/configuring-the-time-service-ntpserver-and-specialpollinterval.aspx\" target=\"_blank\">this post<\/a> for an explanation of the flags. There are four possible flags: 0x01 <code>SpecialInterval<\/code>; 0x02 UseAsFallbackOnly; 0x04 <code>SymmetricActive<\/code>; 0x08 <code>Client<\/code>.<\/p>\n<ul>\n<li>Flag <code>UseAsFallbackOnly<\/code> means the server is only used if the others are unavailable. Check out <a href=\"http:\/\/blogs.technet.com\/b\/askds\/archive\/2007\/11\/01\/configuring-your-pdce-with-alternate-time-sources.aspx\" target=\"_blank\">this post<\/a> for an example of this.<\/li>\n<li>Flag <code>SpecialInterval<\/code> lets you change how often the NTP server is polled. By default the interval is determined by Windows based on the quality of time samples, but you can use the above flag and set a <a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/cc773263%28WS.10%29.aspx#w2k3tr_times_tools_uhlp\" target=\"_blank\">registry key<\/a> <code>HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\W32Time\\TimeProviders\\NtpClient\\SpecialPollInterval<\/code> to change the polling interval.<\/li>\n<li>I am not sure what the other two flags do. The <code>Client<\/code> flag seems to be a commonly used one. Some posts\/ articles use it, others don&#8217;t. The default time.windows.com setting uses this flag as well as the <code>SpecialInterval<\/code>.<\/li>\n<\/ul>\n<p><strong>p.s.<\/strong> To turn on w32tm debugging check out <a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/cc816838%28v=ws.10%29.aspx\" target=\"_blank\">this link<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The w32time service provides time for Windows. Since Windows XP NTP (Network Time Protocol) is supported. Prior to that it was only SNTP (Simple NTP). Non domain joined computers (including servers) use SNTP. This is a good article that explains the Windows Time service and its configurations. Covers both registry keys and GPOs. This is &hellip; <a href=\"https:\/\/rakhesh.com\/windows\/brief-notes-on-windows-time\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Brief notes on Windows Time<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[333,85],"tags":[553,577,352],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/posts\/2745"}],"collection":[{"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/comments?post=2745"}],"version-history":[{"count":0,"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/posts\/2745\/revisions"}],"wp:attachment":[{"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/media?parent=2745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/categories?post=2745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rakhesh.com\/wp-json\/wp\/v2\/tags?post=2745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}