Why does yum return error: [Errno 256] No more mirrors to try ? - Red Hat Customer Portal

Environment Red Hat Enterprise Linux Red Hat Customer Portal Red Hat Subscription Management (RHSM) Red Hat Satellite Issue yum update fails with the error : [Errno 256] No more mirrors to try Resolution Check the network connectivity. If IP based Firewall is being used then whitelist the IPs that are mentioned in Public CIDR Lists for Red Hat (IP Addresses for cdn.redhat.com) for access to the co