添加站点时使用Let’s Encrypt出错

你好，
如题所示，以下是出错信息：
"
IMPORTANT NOTES:
- The following errors were reported by the server:
Domain: example.com
Type: connection
Detail: DNS problem: query timed out looking up A for
example.com
To fix these errors, please make sure that your domain name was
entered correctly and the DNS A record(s) for that domain
contain(s) the right IP address. Additionally, please check that
your computer has a publicly routable IP address and that no
firewalls are preventing the server from communicating with the
client. If you're using the webroot plugin, you should also verify
that you are serving files from the webroot path you provided."