certbot，二次生成ssl证书时报错：The following errors were reported by the server:ssl证书已经被占用

错误：To fix these errors, please make sure that your domain name was    entered correctly and the DNS A/AAAA record(s) for that domain    contain(s) the right IP address.   这个是因为你的域名已经解析过 _acme-challeng

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