Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752158AbXBDIAt (ORCPT ); Sun, 4 Feb 2007 03:00:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752159AbXBDIAt (ORCPT ); Sun, 4 Feb 2007 03:00:49 -0500 Received: from mail1.webmaster.com ([216.152.64.169]:1323 "EHLO mail1.webmaster.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752158AbXBDIAs (ORCPT ); Sun, 4 Feb 2007 03:00:48 -0500 From: "David Schwartz" To: "Linux Kernel Mailing List" Subject: RE: ntp Date: Sat, 3 Feb 2007 23:59:56 -0800 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) Importance: Normal In-Reply-To: <026801c746a6$c3f81780$2801a8c0@zhangxiliang> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Authenticated-Sender: joelkatz@webmaster.com X-Spam-Processed: mail1.webmaster.com, Sun, 04 Feb 2007 00:00:08 -0800 (not processed: message from trusted or authenticated source) X-MDRemoteIP: 206.171.168.138 X-Return-Path: davids@webmaster.com X-MDaemon-Deliver-To: linux-kernel@vger.kernel.org Reply-To: davids@webmaster.com X-MDAV-Processed: mail1.webmaster.com, Sun, 04 Feb 2007 00:00:09 -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1130 Lines: 27 > When i start the ntp service successful on server, the client must ntpdate > with the server after waiting a moment. > The moment may be 3~5 minutes, or it may be 10~15 minutes. I > don't know why > it happens? Two clocks cannot be synchronized instantaneously. It takes time to compare the two clocks and adjust so that they stay in sync. A client will not accept a date from an NTP server whose clock is not synchronized -- why should it? Imagine this -- you have a clock you do not trust. You ask a clock you do trust what time it is, and it tells you it is 10:00. A bit later, I ask you what time it is. Your clock says 10:12. Can you trust that time? Your clock may be fast, it may be slow. You don't know. Until you check the clock you trust a few times and confirm both clocks are flowing at the same rate, you cannot tell the client what time it is when it asks you. DS - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/