Set exact time with ntp

Edit the configuration file to eventually add ntp servers

Edit the file /etc/ntp.conf and look at the server list and add eventually a server:

server 0.europe.pool.ntp.org
server 1.europe.pool.ntp.org
server 2.europe.pool.ntp.org
server 3.europe.pool.ntp.org
server 0.debian.pool.ntp.org iburst
server 1.debian.pool.ntp.org iburst
server 2.debian.pool.ntp.org iburst
server 3.debian.pool.ntp.org iburst

Restart the ntp service

$ sudo /etc/init.d/ntp restart

Check if the computer is synchronized:

$ ntpstat
synchronised to NTP server (XXX.XX.XX.XX) at stratum 3
    time correct to within 137 ms
    polling server every 64 s

Eventually list the status of each server with:

$ ntpq -p

Remark:

You can eventually check the time of your computer on Time.is.

If you want to ask me a question or leave me a message add @bougui505 in your comment.