skip to content

IT Help and Support

University Information Services
 

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 previous IP addresses should continue to work for some time, even 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.

Note that the old ntpX.csx.cam.ac.uk names are still present the DNS and there are currently no plans to remove them.  You should, however, reconfigure clients to use the new names (directly in cam.ac.uk), when the opportunity arises, as they will likely be removed in the future (albeit with advance warning).

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: 14th January 2021

UIS Service Desk

UIS Service Status

Phone padded  Service status line: (01223 7)67999
Website  Sign up for SMS/email status alerts
Website  Read major IT incident reports

UIS bITe-size bulletin

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

Sign up >

Latest news

Obsolete media formats will be removed from the Streaming Media Service on 24 June

17 June 2021

We need to delete old , unsupported media file s from the University’s Streaming Media Service (SMS ) because the system is approaching its max i m um stor a ge capacity . The o riginal high -quality ‘master’ copies will be retained. D eleting old files will allow adequate space for users to add new uploads and ensure the service continues to run smoothly.

Panopto planned maintenance: Saturday 26 June 2021

15 June 2021

Panopto will be undergoing an upgrade from 22:00 on Saturday 26 June until approximately 02:00 on Sunday 27 June and will be unavailable. During this downtime, you won’t be able to access recordings and any attempt to upload content will result in a "Server unable to connect" message. You may also notice an impact on...

Change to IP addresses associated with Raven from 16 June 2021

2 June 2021

The IP addresses associated with raven.cam.ac.uk will be changing on or soon after Wednesday 16 June. This change should be invisible to and have no impact on users, but IT staff who maintain firewall rules that use IP-based filtering to allow access to Raven will need to update their configuration. In addition to the...