Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

• Add epel repo and update

rpm -iUvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm  yum update 

If yum complains that

Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

Then try to run following command to fix it:

yum upgrade ca-certificates --disablerepo=epel