Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
不少朋友在用centos7系统的 以下命令: sudo yum install wget / sudo yum update 会出现以上错误，解决办法为：
sudo sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo sudo sed -i s/^#.*baseurl=http/baseurl=https/g /etc/yum.repos.d/*.repo sudo sed -i s/^mirrorlist=http/#mirrorlist=https/g /etc/yum.repos.d/*.repo
正常情况下，在上面命令执行完成后，也就可以了！
如果提示以下情况，则可以这样解决：
Running yum upgrade -y
failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try. http://vault.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 301 - Moved Permanently
解决方案为：
sudo echo "sslverify=false" >> /etc/yum.conf
