http://centos-hn.viettelidc.com.vn/6.7/updates/x86_64/repodata/fd8c1fcb64e32ff588e93a20dfda7f205841bc090e3c8da42c0b2c2a9cf01938-primary.sqlite.bz2:
[Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404
Not Found"

yum reinstall
 http://mirror.centos.org/centos/6/os/x86_64/Packages/centos-release-6-7.el6.centos.12.3.x86_64.rpm

root@localhost # ping 4.2.2.2     ==> If ping reply not receiving then check internet connection

root@localhost # curl ident.me    ==> This should return your public IP if nothing returns then check your dns configuration in /etc/resolv.conf