Riccardo Castellani <[email protected]> wrote: > If I have 3 internal NTP servers, what do you think if my clients have all > these 3 servers in their configuration ? > According to '5.3.2. Why should I have > more than one clock?' in > 'http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO > > > I read 2 servers, it's worst case, but also 3...
It depends on what you expect and how actively you are monitoring your network. When you want your clients to always have correct time even if a server fails, you need more than one server. There are people who claim that 2 servers is not good because they may have different time and you will not be able to tell which one is right, but in a correctly configured ntp server it will normally not happen that it serves wrong time without noticing it. (EXCEPT when you put that LOCAL clock (127.127.1.0) in the server config, that is one of the reasons why you should always remove that!) So, two servers is perfectly OK when you want to increase reliability on a local network and you have monitoring in place so that when one server dies you will start to repair it before the other server dies too. Also, in many environments it does not really matter when the clients are not synchronized for a couple of hours. So when you have only one server (or only one server configured in the clients), it may still be OK when you have monitoring and someone repairs the server or puts a temporary other server on that address within reasonable time. However, when you have the 3 internal servers it is good to include the server lines in all the clients configs. That is the most reliable situation overall. I only want to indicate that it is not mandatory in cases where you don't need 100% reliability. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
