Why satellite-sync fails with "502 Proxy Error" or Connection timed out error ?

Issue

• Satellite-sync fails with connection timed out error message.

 # /usr/bin/satellite-sync -c rhel-x86_64-server-6 -c rhn-tools-rhel-x86_64-server-6 -c rhel-x86_64-server-optional-6
15:41:15 Red Hat Network Satellite - live synchronization
15:41:15    url: https://satellite.rhn.redhat.com
15:41:15    debug/output level: 1
15:42:18
15:42:18
ERROR: there was a problem synchronizing the information.
       Error message: [Errno 110] Connection timed out

• Satellite-sync fails with "111, 'Connection refused' " error message.

• Satellite-sync fails with "502 Proxy Error"

        2010/01/09 22:00:02 +02:00 Commandline: ['/usr/bin/satellite-sync'] 
        2010/01/09 22:00:02 +02:00 24416 0.0.0.0: rhnSQL/int_oracle.connect('Connecting to database', 'rhnsat') 
        2010/01/09 22:00:02 +02:00 Red Hat Network Satellite - live synchronization 
        2010/01/09 22:00:02 +02:00    url: https://satellite.rhn.redhat.com 
        2010/01/09 22:00:02 +02:00    debug/output level: 1 
        2010/01/09 22:00:03 +02:00 ERROR: ProtocolError: <ProtocolError for satellite.rhn.redhat.com /SAT: 502 Proxy Error> 
        2010/01/09 22:00:03 +02:00 
        2010/01/09 22:00:03 +02:00 
        ERROR: there was a problem synchronizing the information. 
               Error message: <ProtocolError for satellite.rhn.redhat.com /SAT: 502 Proxy Error>

• Satellite-sync fails with "503 Service Temporarily Unavailable" error.

        # /usr/bin/satellite-sync 
        13:01:33 Red Hat Network Satellite - live synchronization 
        13:01:33    url: https://satellite.rhn.redhat.com 
        13:01:33    debug/output level: 1 
        13:01:33 
        13:01:33 
        ERROR: there was a problem synchronizing the information. 
               Error message: <ProtocolError for satellite.rhn.redhat.com /SAT: 503 Service Temporarily Unavailable>