1. Add DNS to the Host 1.1 CentOS The first method: manage DNS with /etc/resolv.conf Disable NetworkManager If you do not disable NetworkManager, the DNS records you add directly to /etc/resolv.conf are lost after you restart the NetworkManager component. 1 2 3 4 vim /etc/NetworkManager/NetworkManager.conf [main] dns=none Add dns=none to the [main] section.

1. About DNS 1.1 What the DNS Service Is For DNS provides a mapping service from domain names to IPs. For example, you type https://www.chenshaowen.com into a browser to open a page, but the data link communicates over IP and cannot recognize www.chenshaowen.com. This is where a DNS lookup comes in: the input is www.