Introduction
There may be times when yum cannot build the cache or search packages due to a bad repository mirror. You can exclude a specific repository mirror using the fastmirror.conf file in /etc/yum/
Procedure
Choose your favorite editor and modify the following file.
/etc/yum/pluginconf.d/fastestmirror.conf
Within the file, make sure that enabled= is set to 1 and under the #exclude, add a new line with exclude = name.of.mirror. Save the file and then rerun the yum clean all and yum makecache commands.
yum clean all; yum makecache