Ntp not updating intimidating questions to ask your boyfriend
Now let’s take a look at configuring NTP with either chronyd or ntpd.By default in Cent OS 7 chrony is the default NTP client/server so it should already be installed if you’re also using this operating system, otherwise you can install it if required as below.By default after installing the package the service will not be running, start chronyd if it’s not already running.Once the service starts it will automatically begin synchronizing time against the NTP servers defined in the configuration file.Public NTP servers on the Internet should already be configured to accept inbound NTP traffic.If you are instead running your own local NTP server within your own network you will need to ensure that your servers can connect inbound to the NTP server on UDP port 123, which can be done by running the following command on your NTP server if firewalld is in use, which is the default in Cent OS 7.Stratum 2 servers then get their time from the stratum 1 servers, while stratum 3 servers synchronize with stratum 2 sources.
In this version chronyd is installed by default, however we will still cover the older ntpd for completeness as this is still widely used.
Your Linux system will generally have two clocks, a hardware clock/real time clock (RTC) and a system clock.
The hardware clock is physically present and continues to run from battery power even if the system is not plugged into a power source, this is how the time stays in place when there is no power available.
If you have your own local NTP server you can modify the configuration to use this instead, be sure to reload the service afterwards to apply the changes.
The NTP servers may also be retrieved by DHCP configuration, this can be disabled by specifying PEERDNS=no in the network configuration.