NTP - Network Time Protocol

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NTP (Network Time Protocol) is a means of transmitting time signals over a computer network. It is typically used to synchronize a computer's time with reliable and geographically-close time sources.

For devices on LBNL networks in the San Francisco Bay Area, LBLnet recommends configuring these five GPS-synchronized NTP servers:

DNS Host NameLocation


LBNL Bldg 50 Complex


LBNL Bldg 50 Complex

ntp3.lbl.govUC Berkeley
ntp4.lbl.govUC Berkeley

While configuring all 5 is recommended, some devices may only accept 1 or 2 NTP servers, in which case, we recommend using the LBNL Bldg 50 Complex servers.

Specifying NTP server by DNS Host Name is the preferred method, but not all devices may be capable of doing so, and may require specifying an IP address instead. You can use a DNS query in Command Prompt or Terminal to determine the current IP address of a server. Below are examples of commands to do so:

> nslookup ntp1.lbl.gov
> host ntp2.lbl.gov
> dig ntp3.lbl.gov

(Note that the output of nslookup first includes the DNS server that responded to your query in the "Server" field, while the answer to that query typically follows the "Name" field.)

Getting Started

  • Windows computers joined to the LBNL Active Directory domain already use NTP and should not require additional configuration.
  • Stand-alone Windows 7 computers:
    • Click the clock on the menu bar and choose "Change date and time settings"
    • Select the Internet Time tab and click "Change settings"
    • Check "Synchronize with an Internet time server"
    • Specify an NTP server and click OK
  • Mac OS X
    • Click on the menu bar clock
    • Open Date & Time Preferences
    • Check "Set date and time automatically" and specify an NTP server in the box next to it
  • Linux/Unix
    • See server definitions in /etc/ntp.conf
    • Restart the ntpd service


Call the Helpdesk at ext. 4357 (486-4357) or e-mail help@lbl.gov.


The service is part of the Berkeley Lab Technology Resource Kit and is provided to all employees and affiliates at no recharge.