After a fresh installation of CentOS in a new machine, the OS can not automatically connect to the network by default. So, the user/admin should manually change few setting so that the new system can gain a new IP address and connect to the internet.
To start, type nmcli d to check if the NIC card is installed properly.
Now the nmtui will open up the network manager setting for the centOS.
Choose the Edit a connection option
Choose the network interface and activate
Now, Click edit to configure the network settings
Check on the automatically connect option and OK to exit from network manager
Restart the network services
Enter the password of the root to commit the changes
Use the command IP a to see the IP configuration detail of the interfaces.
Ping google.com to check if the machine can connect to the internet.