While updating Red Hat Enterprise Linux client systems via RHN Proxy fails with 'Error Class Code: 1000'

Issue

• While trying to update  RHEL servers using yum/up2date fails with following error:

RHN Proxy could not successfully connect its RHN parent. Please contact your system administrator.  
Error Class Code: 1000  
Error Class Info: RHN Proxy error.  
Explanation:  
   An error has occurred while processing your request. If this problem persists please enter a bug report at bugzilla.redhat.com.  
   If you choose to submit the bug report, please be sure to include details of what you were trying to do when this error occurred and details on how to reproduce this problem.  

• /var/log/rhn/rhn_proxy_broker.log contains entries like the following:

 2010/07/29 12:24:23 +11:00 2882 10.32.247.40: proxy/apacheServer.\_\_call\_\_('New request, component proxy.broker',)  
 2010/07/29 12:24:23 +11:00 2882 10.32.243.201: broker/rhnBroker.handler  
 2010/07/29 12:24:23 +11:00 2882 10.32.243.201: proxy/rhnShared._connectToParent('ERROR', 'Error opening connection', 'https://host.example.com/XMLRPC', <socket.gaierror instance at 0x2b8db8c93b00>)  
 2010/07/29 12:24:23 +11:00 2882 10.32.243.201: proxy/apacheHandler.cleanupHandler