Hi

Just letting you know that there may be an issue with yum and https for your mirrors.

I haven't tested extensively but

Using CentOS 6.6 x86_64 epel-release-6-8.noarch

 yum repolist
Loaded plugins: fastestmirror, priorities, security
Determining fastest mirrors
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

 wget 'https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=x86_64&arch=x86_64' works as expected.

I am sure proxy configuration is not the issue as the test system has direct Internet access.

I have confirmed that if I change the mirrorlist url to http things work as expected

Thanks and let me know if I can provide an other information :)