NTP is a component of PennNet's Network Names & Numbers.
PennNet NTP Service
Using NTP on PennNet
- Apple macOS - In the Date & Time section of the System Preferences, choose the
Date & Time
tab, checkSet date and time automatically
, and enter the three server hostnames separated by commas, like this:
timeserver1.upenn.edu, timeserver2.upenn.edu, timeserv
er3.upenn.edu
- Microsoft Windows - From a command prompt (Start → type '
cmd
' → right click the shortcut and run as administrator), issue the following commands to set the server list and force the computer to resynchronize.
w32tm /config /syncfromflags:manual /manualpeerlist:"timeserver1.upenn.edu timeserver2.upenn.edu timeserver3.upenn.edu"
w32tm /config /update
- Linux/BSD/*nix - Refer to the documentation for your platform (e.g. Ubuntu, Red Hat, FreeBSD, or Solaris). In most cases, you will be able to add the following lines to ntp.conf, and restart the ntpd service.
server timeserver1.upenn.edu iburst
server timeserver2.upenn.edu iburst
server timeserver3.upenn.edu iburst
PennNet NTP
NTP Architecture
Each of the three NTP servers is equipped with an embedded reference clock, which is set and disciplined by a radio receiver. The units receive L-band radio signals from the Global Positioning System (GPS) satellites.
NTP Server Specifications
- Model: Meinberg LANTIME M300
- Reference clock: GPS
Frequently Asked Questions
If your systems are configured to receive NTP from any of the following names or IP addresses, you should update your configuration as soon as possible to use active, supported time servers.
The retired NTP servers were:
-
ntp-server-1.upenn.edu
noc1.dccs.upenn.edu
128.91.2.13
2607:f470:1001::1:1 -
ntp-server-2.upenn.edu
noc2.dccs.upenn.edu
128.91.254.1
2607:f470:1002::2:2 -
ntp-server-3.upenn.edu
noc3.dccs.upenn.edu
128.91.251.158
2607:f470:1003::3:3
Yes and no. The central DHCP servers will return NTP server IP addresses to clients that request them (DHCP option 42). The NTP servers do not perform broadcast or multicast protocol operations.
The Network Time Foundation maintains a site with copious reference material and links to additional information.
Visit the Time and Frequency Division of the National Institute of Standards and Technology (NIST) to learn more about the Internet Time Service and WWVB Radio Station.
Though we tend to think of its positioning and navigation applications, the Global Positioning System (GPS) also provides high-performance timing signals, which represent another key component of the PennNet NTP Service.