nanog mailing list archives
Re: NTP Server
From: Cutler James R <james.cutler () consultant com>
Date: Sun, 24 Oct 2010 20:43:50 -0400
Regarding leap seconds: A modern OS kernel using the NTP daemon to control time will always experience monotonic time. Negative leap seconds should result in the local clock slowing slightly until the local time matches the NTP-derived time. This is in strong contrast to what can happen when ntpdate or similar queries are used to adjust system time, as in the following example from a popular CPE log where the local CPU clock tended to run fast: Oct 24 04:27:59 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 05:28:00 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 06:28:00 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 07:28:01 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 08:28:01 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 09:28:02 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 10:28:03 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 11:28:04 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 12:28:04 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 13:28:05 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 14:28:05 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 15:28:05 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 16:28:06 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 17:28:07 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 18:28:08 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Oct 24 19:28:08 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted +0 seconds). Oct 24 20:28:09 192.168.1.1 HomeN ntp: Clock synchronized to network time server time.apple.com (adjusted -1 seconds). Regarding local time servers: This is the situation in which local clients, at least those with UNIX or UNIX-like OS can take advantage of ntpd and local time servers to have consistent and monotonic time across your network with a measure of insulation from external vagaries. Yes, I have run ntpd on Windows systems, but have no quotable experience with the current Windows version (Windows 7). James R. Cutler james.cutler () consultant com
Current thread:
- Re: NTP Server, (continued)
- Re: NTP Server Joe Greco (Oct 25)
- Re: NTP Server Nick Hilliard (Oct 25)
- Re: NTP Server Joe Greco (Oct 25)
- Re: NTP Server Robert E. Seastrom (Oct 25)
- Re: NTP Server William F. Maton Sotomayor (Oct 26)
- Re: NTP Server Joel Jaeggli (Oct 24)
- RE: NTP Server Brandon Kim (Oct 24)
- Re: NTP Server Cutler James R (Oct 24)
- RE: NTP Server Sean Donelan (Oct 24)
- Re: NTP Server John Kristoff (Oct 25)
- Re: NTP Server Marshall Eubanks (Oct 24)
- Re: NTP Server Dobbins, Roland (Oct 24)
- Re: NTP Server Jorge Amodio (Oct 24)
- Re: NTP Server Sean Donelan (Oct 24)
- Re: NTP Server Seth Mattinen (Oct 24)
- Re: NTP Server Marcus Reid (Oct 25)