Working in the financial world, the best practices is to have 4 ntp servers (if not using PTP).
1) You need 3 to determine the correct time (and detect bad tickers) 2) If you lose 1 of the 3 above, then you no longer can determine the correct time 3) Therefore with 4, you have redundancy. We have two Symmetricom Stratum 1 time servers synced via GPS with Rubidium oscillators, and two RHEL 6 servers running ntpd for our 4 servers. ---- Matthew Huff | 1 Manhattanville Rd Director of Operations | Purchase, NY 10577 OTA Management LLC | Phone: 914-460-4039 -----Original Message----- From: Roy [mailto:r.engehau...@gmail.com] Sent: Friday, February 7, 2014 10:23 AM To: nanog@nanog.org Subject: Re: Need trusted NTP Sources On 2/7/2014 3:35 AM, Saku Ytti wrote: > On (2014-02-06 21:14 -0500), Jay Ashworth wrote: > >> My usual practice is to set up two in house servers, each of which >> talks to: >> >> And then point everyone in house to both of them, assuming they >> accept multiple server names. > Two is worst possible amount of NTP servers to have. Either one fails > and your timing is wrong, because you cannot vote false ticker. And > chance of either of two failing is higher than one specific of them. > "A man with a watch knows what time it is. A man with two watches is never sure."
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