Do not report this post as a duplicate post. It is not a duplicate. This error appears in my other post but it is not what is actively being resolved there. That issue is for an in place upgrade not a yum update error.

Red Hat Enterprise Linux Server release 6.10 (Santiago)

[root@localhost ~]# yum update -y
Loaded plugins: product-id, rhnplugin, search-disabled-repos, security, subscription-manager
There was an error communicating with RHN.
RHN Satellite or RHN Classic support will be disabled.
rhn-plugin: Error communicating with server. The message was:
Name or service not known

RHEL6 is EOL. You need to buy "Extended life cycle support (ELS) add-on" to get further updates for it.

Inplace-Upgrade is not supported by RH.