Fix CentOS 7 Network Hostname Connectivity Issues

In CentOS 7, issues with network and hostname not being connected can be caused by various reasons, here are some possible solutions:

1. Check the network connection: First make sure the network connection is working properly, you can use the ping command to test if the network connection is smooth, for example, ping www.google.com.
2. Check network settings: Verify if network settings are correct by modifying the network configuration files located in /etc/sysconfig/network-scripts/ifcfg-eth0 or /etc/sysconfig/network-scripts/ifcfg-enp0s3 (depending on the network card name), ensuring that IP address, gateway, DNS, and other settings are accurate.
3. Restarting network services: You can try restarting the network services to resolve network connection issues by using the command systemctl restart network.
4. Check the hostname configuration: Verify the correctness of the hostname, which can be edited in the /etc/hostname file or set using the command hostnamectl set-hostname yourhostname.
5. Check DNS settings: Make sure the DNS settings are correct, you can modify the /etc/resolv.conf file to set the DNS server.

If the above methods do not solve the issue, it is recommended to check if the network hardware is functioning properly, verify if firewall settings are blocking the network connection, or try restarting the system to see if that resolves the problem. If the issue persists, further investigation into system logs may be necessary to determine the root cause of the problem.