Installing and Administering Internet Services

Chapter 7 293
Configuring the Network Time Protocol (NTP)
Getting Started with NTP
Example 3: Evaluating Time Servers in Australia
Look at a time server in Australia. Here are the details:
ntp.adelaide.edu.au (129.127.40.3)
Location: University of Adelaide, South Australia
Synchronization: NTP V3 secondary (stratum 2), DECsystem
5000/25 Unix
Service Area: AARNet
Access Policy: open access
Contact: Danielle Hopkins ([e-mail])
/usr/sbin/ping ntp.adelaide.edu.au 64 5
PING huon.itd.adelaide.edu.AU: 64 byte packets
64 bytes from 129.127.40.3: icmp_seq=0. time=498. ms
64 bytes from 129.127.40.3: icmp_seq=1. time=500. ms
64 bytes from 129.127.40.3: icmp_seq=2. time=497. ms
64 bytes from 129.127.40.3: icmp_seq=3. time=498. ms
64 bytes from 129.127.40.3: icmp_seq=4. time=496. ms
----huon.itd.adelaide.edu.AU PING Statistics----
5 packets transmitted, 5 packets received, 0% packet loss
round-trip (ms) min/avg/max = 496/497/500
Assume you are located in western United States and you ping this time
server. The ping round-trip times are much larger; around 500
milliseconds. Do not use a time server at this distance unless you are
really desperate and understand what 500 milliseconds step changes
mean to your users and applications. However, depending on your
location, ping round trip times from this server may be acceptable levels.
The round-trip times from your own location might be much smaller.
Also note that the variation in round-trip times is small.