skip to primary navigationskip to content
 

Network Time Protocol (NTP)

The Network Time Protocol (NTP) keeps a computer's clock synchronised to the correct time. The UIS provides an NTP service that aims to provide millisecond-accurate time to systems within the University.

There are two ways to use the service: via NTP and SNTP - they are described below.

NTP Service

The NTP service is intended for use by clients which run a full implementation of the NTP protocol, including calculating network delays and jitter.

There are four NTP servers, resolvable by DNS hostname at  ntp0.cam.ac.ukntp1.cam.ac.ukntp2.cam.ac.uk and ntp3.cam.ac.uk.  The IP addresses these resolve to may change occasionally and must be re-resolved by DNS and updated periodically, at least once per year (the old addresses should continue to work for sometime, after they cease to be advertised).

The individual hosts providing this service are not redundant and may be unavailable for short periods of time: redundancy is achieved through the client talking to multiple servers.  Clients must be configured with a minimum of three of the above hosts.

SNTP Service

Clients which do not implement the full NTP protocol and just retrieve the time from the first available server, without calculating delays and jitter, should use the SNTP (Simple Network Time Protocol) service.

The SNTP service is provided at a single host, resolvable by DNS hostname  sntp.cam.ac.uk.  As with the NTP service hostnames, the addresses this resolves to may change occasionally so must be re-resolved periodically, at least once per year.

This address is redundant and will fail over to another host, if the normal host providing it becomes unavailable, so clients should only need configuring with the single server.  Clients which do not support being configured with three or more servers should use this service instead of the full NTP service.

Last modified: 19th March 2019

Contact

If you have any enquiries regarding UIS network services, or other University network topics, please send an email to:

Getting help


UIS Service Desk
General support queries

  Phone padded  (01223 7) 62999

UAS Service Desk
Administrative staff queries

  Phone padded  (01223 3) 32999

UIS bITe-size bulletin


A regular newsletter aimed at the University's IT community, highlighting service and project news from UIS.

Sign up >  |  Back issues

UIS Service Status

Phone padded  Service status line: (01223) 463085
Website padded  Sign up for SMS/email status alerts

RSS Feed Latest news

All University members now have access to Google G Suite@Cambridge

May 07, 2019

UIS enrolled all members of the University in our Google G Suite account, known as G Suite@Cambridge, on 2 May.

Upgrade Windows 7 machines before the operating system reaches end of life on 14 January 2020

Apr 30, 2019

Microsoft will stop supporting Windows 7 on 14 January 2020. The good news is that you may be entitled to a free upgrade to Windows 10, if your institution is participating in the University's EES agreement.

View all news