[Errno 256] No more mirrors to t

yum -y install gcc perl pcre-devel openssl openssl-devel gcc-c++ zlib zlib-devel libreadline-dev libncurses5-dev libpcre3-dev libssl-dev

下载软件包出错：
gcc-4.4.7-18.el6.x86_64: failure: Packages/gcc-4.4.7-18.el6.x86_64.rpm from base: [Errno 256] No more mirrors to try.
gcc-c++-4.4.7-18.el6.x86_64: failure: Packages/gcc-c++-4.4.7-18.el6.x86_64.rpm from base: [Errno 256] No more mirrors to try.
libstdc++-devel-4.4.7-18.el6.x86_64: failure: Packages/libstdc++-devel-4.4.7-18.el6.x86_64.rpm from base: [Errno 256] No more mirrors to try.
cpp-4.4.7-18.el6.x86_64: failure: Packages/cpp-4.4.7-18.el6.x86_64.rpm from base: [Errno 256] No more mirrors to try.

[Errno 256] No more mirrors to try. 得知这可能是错误的缓存源导致，直接两个命令解决：
yum clean all
yum makecache