Udev may assign random Network Card Interface names for some
            network cards such as enp2s1. If you are not sure what your
            Network Card Interface name is, you can always run ip l after you have booted your
            system. It is important that the Name
            variable in /etc/systemd/network
            contain the correct Network Card Interface name (e.g.
            Name=enp2s1 or Name=eth0) or systemd will fail to bring up your
            network interface.
          
            systemd-networkd
            uses /etc/systemd/network for
            configuration files. Refer to systemd.network(5) and
            systemd.netdev(5). Configure a network interface with a config
            file. Adjust Name= as required:
          
cd /etc/systemd/network && cat > static.network << "EOF" [Match] Name=enp2s0 [Network] Address=192.168.1.1/24 Gateway=192.168.1.2 EOF
The values of these variables must be changed in every file to match the proper setup.
            The Name variable defines the
            interface name, for example, eth0. It is required for all network
            device configuration files.
          
            The Gateway variable should contain
            the default gateway IP address, if one is present. If not, then
            comment out the variable entirely.
          
For more information see the systemd.netdev man page.
            systemd-networkd
            uses /etc/systemd/network for
            configuration files. Refer to systemd.network(5) and systemd.netdev(5). Configure a network
            interface with a config file. Adjust Name= as required:
          
cd /etc/systemd/network && cat > dhcp.network << "EOF" [Match] Name=enp2s0 [Network] DHCP=yes EOF
            systemd-networkd
            will automatically configure /run/systemd/network/resolv.conf when using
            DHCP. If you did not manually create /etc/resolv.conf, create a symlink:
          
ln -sv /run/systemd/network/resolv.conf /etc
Systemd includes a simple NTP client daemon, systemd-timesyncd, though it is disabled by default. If you want to enable it, you will first need to add a required user and group:
groupadd -g 78 systemd-timesync useradd -g systemd-timesync -u 78 -d /dev/null -s /bin/false systemd-timesync
Then, actually enable systemd-timesyncd so that it will run on system boot:
systemctl enable systemd-timesyncd
          You can configure systemd-timesyncd by editing
          /etc/systemd/timesyncd.conf.
        
Continue to Making the CLFS System Bootable.