What are the reasons for the CentOS network card configuration not taking effect?

There can be multiple reasons why network card configuration does not take effect in CentOS systems, common reasons include:

1. Configuration file error: There is an error in the network card configuration file (usually located in the /etc/sysconfig/network-scripts/ directory) such as incorrect IP address, gateway, subnet mask, etc.
2. Incorrect network card naming: CentOS 7 and above versions have introduced new network card naming rules, which may result in the network card name in the configuration file not matching the actual network card name.
3. If the network service restart fails: After modifying the network card configuration file, the network service must be restarted in order for the changes to take effect. If the network service restart fails, the configuration will not be effective.
4. Network card driver issue: Incorrect installation of the network card driver or driver version incompatibility may cause invalid network card configuration.
5. Conflict of network management tools: If multiple network management tools are used in the system (such as NetworkManager and systemd-networkd), it may lead to configuration conflicts, rendering network card configurations invalid.
6. Internet connection issues: If there are problems with the network card connection, such as loose Ethernet cables or faulty switch ports, it will cause the network card to not work properly.
7. Firewall configuration issue: Incorrect firewall configuration may block network traffic and make network card configuration invalid.

The above are some common reasons for the CentOS network card configuration not taking effect, depending on the specific situation, they can be checked one by one.