2.2.5. Implementing Server Failover

Beginning with up2date-4.2.38, the Red Hat Update Agent can be configured to seek updates from a series of RHN Servers. This can be especially helpful in sustaining constant updates if your primary RHN Proxy Server or RHN Satellite Server may be taken offline.
To use this feature, first ensure that you are running the required version of up2date. Then manually add the secondary servers to the serverURL and noSSLServerURL settings in the /etc/sysconfig/rhn/up2date configuration file (as root). Add the fully qualified domain names (FQDN) for the Proxy or Satellite immediately after the primary server, separated by a semicolon (;). For example:
serverURL[comment]=Remote server URL
serverURL=https://your_primary.your_domain.com/XMLRPC; 
https://your_secondary.your_domain.com/XMLRPC;

noSSLServerURL[comment]=Remote server URL without SSL
noSSLServerURL=http://your_primary.your_domain.com/XMLRPC; 
https://your_secondary.your_domain.com/XMLRPC;
Connection to the servers is attempted in the order provided here. You can include as many servers as you wish. You may list the central RHN Servers, as well. This makes sense, however, only if the client systems can reach the Internet.