How to fix the network card not starting in CentOS 7?

If the network card on CentOS 7 cannot start, there may be several reasons and solutions.

1. Check the physical connections: First, make sure the network cable is properly connected, and that the network card is inserted correctly.
2. Check the network card driver: Make sure the network card driver is correctly installed. You can use the lspci command to view the network card model, and then download and install the corresponding driver from the official website.
3. Check the network card configuration file: locate the corresponding network card configuration file in the /etc/sysconfig/network-scripts/ directory, usually named as ifcfg- such as ifcfg-eth0. Make sure the parameters in the configuration file are set correctly, especially the setting of ONBOOT to yes, indicating the network card will start automatically during boot.
4. Check network services: Make sure that network services have been correctly started. You can use the “systemctl status network” command to check the running status of network services. If it’s not running, you can use the “systemctl start network” command to start the network services.
5. Restarting network services: If the above steps do not resolve the issue, you can try restarting the network services by using the command “systemctl restart network”.
6. Disable the Network Manager service: If you are using the Network Manager, you can try disabling the service, which may resolve some issues where network cards fail to start. You can stop the service using the command systemctl stop NetworkManager and disable the service using systemctl disable NetworkManager.

If the above methods still cannot solve the problem, it may be due to hardware failure or other more complex network configuration issues. It is recommended to contact the network administrator or professional for further diagnosis and repair.