Docker容器内无法解析DNS的问题 Could not resolve host

在docker容器内使用  yum 或者 wget 命令，会提示  cannot resolving host address 无法解析主机地址  ，也就是容器内无法解析DNS。

Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock32 error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
 
One of the configured repositories failed (Unknown),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:
 
 1. Contact the upstream for the repository and get them to fix the problem.
 
.....................................................................
 4. Configure the failing repository to be skipped, if it is unavailable.
    Note that yum will try to contact the repo. when it runs most commands,
    so will have to try and fail each time (and thus. yum will be be much
    slower). If it is a very temporary problem though, this is often a nice
    compromise:
 
        yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=true

度娘找到一个方案，我在这里使用了其中的  1. 宿主机防火墙开启伪装IP功能  方案，解决了问题。

放上该博客： https://my.oschina.net/u/580483/blog/4264763/print