yum 安装 sysstat  报错了：

Kylin Linux Advanced Server 10 - Os                                               0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'ks10-adv-os':- Curl error (6): Couldn't resolve host name for http://update.cs2c.com.cn:8080/NS/V10/V10SP2/os/adv/lic/base/aa
rch64/repodata/repomd.xml [Could not resolve host: update.cs2c.com.cn]
Error: Failed to download metadata for repo 'ks10-adv-os': Cannot download repomd.xml: Cannot download repodata/re
pomd.xml: All mirrors were tried

说人话：

Kylin Linux高级服务器10-Os 0.0 B/s | 0 B 00:00
下载存储库“ks10 adv os”的元数据时出错：
-卷曲错误（6）：无法解析的主机名http://update.cs2c.com.cn:8080/ns/v10/v10sp2/os/adv/lic/base/aa
rch64/reportdata/reportmd.xml[无法解析主机：update.cs2c.com.cn]
错误：未能下载repo'ks10adv-os'的元数据：无法下载repod.xml：无法下载repodata/re
pomd.xml:已尝试所有镜像

进入源目录看看

 cd /etc/yum.repos.d

源没有问题!!!

那就是域名解析有问题了。

检查一下hosts 

检查一下DNS

最终确定是DNS 问题，解决了。

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