I have three RHEL 6.6 servers.  One has a yum repository that I know works.  The other two servers I will refer to as yum clients.  These two are configured to use the same yum repository (the first server described).  When I do yum install httpd on each of these two yum client servers, I get two different results.  One server prepares for the installation as normal and prompts me with a y/n prompt.  The second server says No package httpd available.The /etc/yum.conf files on each of the two servers is identical.  The /etc/yum.repos.d/ directories have the same .repo files.  Why does one yum client not see the httpd package?  I use httpd as an example.  One yum client cannot install any package.  The other yum client can install anything.  Neither have access to the Internet or different servers the other one does not have access to.
How do I troubleshoot a yum repository problem that has an error No package ... available error?
rhel;yum