How to resolve the “name or service not known” error on CentOS?

The error occurred because the system could not resolve the specified host name or service name. To fix this error, follow these steps:

1. Check your network connection to ensure it is working properly. You can try using the ping command to test if you can reach the host. For example, type: ping www.example.com.
2. Check the hostname: Make sure the hostname or service name you entered is correct. Check for any spelling errors or other mistakes.
3. Check DNS configuration: If you are using a static IP address, make sure that the DNS server is correctly configured. You can edit the /etc/resolv.conf file and add the correct DNS server address.
4. Check firewall settings: If a firewall is enabled on your system, make sure that the relevant ports are not blocked. You can configure firewall rules using the firewall-cmd command or the iptables command.
5. Check the host file: Review the /etc/hosts file to ensure that the hostname you are querying is correctly mapped to the IP address. You can edit the file and add the correct mapping relationship.

If the above methods still cannot solve the problem, you may need to further examine the network configuration or contact the network administrator for assistance.