ntpd server on FC2

[Paul Howarth]

Brian Fahrlander wrote:
> Won'tcha try putting "server pool.ntp.org" in there three times and
> letting someone else be the standard?  Later, if you get a single
> machine with good uptimes and network speed, you can become of those
> members of the pool, too.

I was a bit curious about how this was supposed to work, but I got it eventually.

pool.ntp.org is a name that resolves to a bunch of different IP addresses, 
using a round-robin scheme so that successive lookups will get different 
addresses. So adding something like:

server pool.ntp.org
server pool.ntp.org
server pool.ntp.org

will result in three different servers from the pool being selected. So far, 
so good. But servers in an ntp.conf file traditionally also have another line 
in there for each server:

restrict pool.ntp.org mask 255.255.255.255 nomodify notrap noquery

There is no way to make sure that the pool.ntp.org addresses in the "restrict" 
line are the same pool.ntp.org addresses used in the "server" line, so it's 
not possible to block off outside hosts from querying the time server using a 
restrict line. This was the problem I couldn't get my head round. But then it 
dawned on me that the point of the exercise was that the time server 
*shouldn't* be blocking off queries from outside hosts, rather the opposite: 
the time server should join the pool and *encourage* outside hosts to use it. 
Eureka!

Paul.