Oracle Exadata’s Exachk script has a validation which prevents it from auto-updating if your system does not have direct ICMP access to updates.oracle.com. This is stupid, as most Exadata machines are not going to have that kind of exposure to the Internet at large. Yes, they will be firewalled, and so, no, ping will not work.
The fix is to find the line containing #Validation1: URL host reachable or not and comment out or remove the return 33 lines below that. (i.e. invalidate the check by commenting it out)
The Exachk script will then bypass the ping test and continue with wget or curl to retrieve the latest version of itself for install.
Be sure to have set both http_proxy and https_proxy environment variables to an appropriate value or the download will still not work. (updates.oracle.com should be accessed over https).
I don’t know who thought a ping validation was a good idea. It’s not.