We run a local NTP time-synchronisation service for Informatics, and recommend that self-managed machines on our network are set up to use it rather than remote timeservers. There are four machines - ntp0.inf.ed.ac.uk, ntp1.inf.ed.ac.uk, ntp2.inf.ed.ac.uk, and ntp3.inf.ed.ac.uk For robustness you should configure your machine to synchronise to as many of these as your system will allow.
These are not accessible from outside the EdLAN network. If you would like to use timeservers from outside, you should use a public service, for example pool.ntp.org, time.google.com, time.windows.com, time.apple.com.
Time synchronisation is useful to users to show correct dates and times, ensure that log files can be accurately correlated across systems, and sychronised time is assumed by authentication technologies such as Kerberos.
Ubuntu desktop installations are configured by default to use ntp.ubuntu.com and should need no further configuration. The command timedatectl status should show "System clock synchronized: yes". Ubuntu 26.04 (Resolute Racoon) defaults to the chrony time daemon and detailed information can be displayed with the chronyc tracking command.