Hello I have download the minimal release of CENTOS 7 at this url link download ISO centos 7.x
All work correctly...the PING and the network is OK. I ping to external HO
I landed here because I had added a bad mirror for a different dependency (passenger, for a Rails app), and solved this problem by just deleting the bad mirror:
rm /etc/yum.repos.d/YOUR-BAD-DEPENDENCY-NAME.repo
e.g.
rm /etc/yum.repos.d/passenger.repo