Dear All, I would say 3 ntp servers are also fine and good enough as there are never taken more than 3 servers. If there are no stratum-1 server available I would define at least 4 pools for these 3 NTP servers.
I can tell you what I have done. Without claim to be correct. I have 3 stratum-1 server ( GPS, DCF77 and rubidium disciplined ) The GPS and DCF77 are peered with the same type of server with another organisation. In case the stratum-0 source would fail. Below this I have 4 stratum-2 server which have also upstream servers from the Internet. Just in case all 3 internal stratum-1 would fail. There I am using two different types of daemon software. And 3 of these 4 servers are public available as part of the AT-pool (Austrian) for IPv6. And internally I use only 2 stratum-3 servers for all clients. Good enough as I manage and monitor complete NTP infrastructure. These stratum-3 servers have defined all 4 of my stratum-2 servers I have and are not using any external time source. In my opinion it is not important to be accurate within a millisecond to the real time. It is more important that all devices have the same time. This becomes interesting especially if there is a leap second. Therefore all clients are not allowed to fetch the time from Internet and such traffic is prohibited by firewall. To avoid that mis-configured clients have NO time I am using RPZ ( restricted policy zones ) in DNS where a lot of well known DNS names for NTP servers are rewritten to the internal IP address. Kind regards Hans — > On 08.04.2023, at 13:37, Terje Mathisen <terje.mathi...@tmsw.no> wrote: > > Renzo Marengo wrote: >> Il giorno venerdì 7 aprile 2023 alle 13:44:59 UTC+2 David Woolley ha >> scritto: >>> On 07/04/2023 10:47, Renzo Marengo wrote: >>>> I know NTP server numbers must be 1, 3 or 4,.... >>> I don't understand this. NTP servers don't have numbers. They do >>> have a stratum, but that is determined automatically from the >>> current time distribution tree. >> I wanted to say... the number (quantity) of ntp server. Now I have 3 >> ntp server(NTP1, NTP2, NTP3), if I had had 2 servers it should be >> always a good idea ? I remembered there was a reason to have a >> similar quantity (that is 3) >> Server A has stratum 2 Server NTP1, NTP2, NTP3 has stratum 3 >> What do you think if I destroyed the Server A and I converted the >> NTP1, NTP2, NTP3 to stratum 2 ? I would link these 3 server to the to >> same time source of server A. > Your clients should all have at least 4 sources, so if you don't want them to > talk to the outside world, that means having at least that many internal > servers for them to reference. > > Terje > > -- > - <Terje.Mathisen at tmsw.no> > "almost all programming can be viewed as an exercise in caching" > -- > This is questions@lists.ntp.org > Subscribe: questions+subscr...@lists.ntp.org > Unsubscribe: questions+unsubscr...@lists.ntp.org > > > > -- This is questions@lists.ntp.org Subscribe: questions+subscr...@lists.ntp.org Unsubscribe: questions+unsubscribe@li
