yum fails installing git on RHEL: There was an error communicating with RHN

yum install git-core

Loaded plugins: product-id, rhnplugin, security
There was an error communicating with RHN.
RHN Satellite or RHN Classic support will be disabled.
Error communicating with server. The message was:
Name or service not known
Setting up Install Process
No package git-core available.
Error: Nothing to do

First I check in cat /etc/yum.conf

[main]
cachedir=/var/cache/yum/$basearch/$releasever
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=3

#  This is the default, if you make this bigger yum won't see if the metadata
# is newer on the remote and so you'll "gain" the bandwidth of not having to
# download the new metadata and "pay" for it by yum not having correct
# information.
#  It is esp. important, to have correct metadata, for distributions like
# Fedora which don't keep old packages around. If you don't like this checking
# interupting your command line usage, it's much better to have something
# manually check the metadata once an hour (yum-updatesd will do this).
# metadata_expire=90m

# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

and nothing seems wrong.
Then I check in
cat /etc/sysconfig/rhn/up2date

# Automatically generated Red Hat Update Agent config file, do not edit.
# Format: 1.0
tmpDir[comment]=Use this Directory to place the temporary transport files
tmpDir=/tmp

disallowConfChanges[comment]=Config options that can not be overwritten by a config update action
disallowConfChanges=noReboot;sslCACert;useNoSSLForPackages;noSSLServerURL;serverURL;disallowConfChanges

skipNetwork[comment]=Skips network information in hardware profile sync during registration.
skipNetwork=0

stagingContent[comment]=Retrieve content of future actions in advance
stagingContent=1

networkRetries[comment]=Number of attempts to make at network connections before giving up
networkRetries=1

hostedWhitelist[comment]=RHN Hosted URL's
hostedWhitelist=

enableProxy[comment]=Use a HTTP Proxy
enableProxy=0

writeChangesToLog[comment]=Log to /var/log/up2date which packages has been added and removed
writeChangesToLog=0

serverURL[comment]=Remote server URL (use FQDN)
serverURL=http://pluto.pippo.com/XMLRPC

proxyPassword[comment]=The password to use for an authenticated proxy
proxyPassword=

stagingContentWindow[comment]=How much forward we should look for future actions. In hours.
stagingContentWindow=24

proxyUser[comment]=The username for an authenticated proxy
proxyUser=

versionOverride[comment]=Override the automatically determined system version
versionOverride=

sslCACert[comment]=The CA cert used to verify the ssl server
sslCACert=/usr/share/rhn/RHNS-CA-CERT

retrieveOnly[comment]=Retrieve packages only
retrieveOnly=0

debug[comment]=Whether or not debugging is enabled
debug=0

httpProxy[comment]=HTTP proxy in host:port format, e.g. squid.redhat.com:3128
httpProxy=

useNoSSLForPackages[comment]=Use the noSSLServerURL for package, package list, and header fetching (disable Akamai)
useNoSSLForPackages=0

systemIdPath[comment]=Location of system id
systemIdPath=/etc/sysconfig/rhn/systemid

enableProxyAuth[comment]=To use an authenticated proxy or not
enableProxyAuth=0

noReboot[comment]=Disable the reboot actions
noReboot=0

The "serverURL=http://pluto.pippo.com/XMLRPC" looks suspicious, since I am not in the pippo.com network...there must be some proxy issue here... but enableProxy is 0!!!

I find some light here. But they don't say what the "default Red Hat Network URL" is... bloody hell...

If I comment out the serverURL I get:

yum install git-core
Loaded plugins: product-id, rhnplugin, security
There was an error communicating with RHN.
RHN Satellite or RHN Classic support will be disabled.

Error Message:
        Please run rhn_register as root on this client
Error Class Code: 9
Error Class Info: Invalid System Credentials.
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.

Ok it looks like I need some good RH training...