eg ping http://www.google.com
ping: unknown host http://www.google.com
eg
host http://www.bigpond.com
;; connection timed out; no servers could be reached
if I add an entry for the host in the /etc/hosts file then the ping gets a response from the ip address resolved from the hosts file.
When I looked at the /etc/resolv.conf file
I found the problem I had the wrong DNS Servers defined
I changed the dns servers to my ISP's DNS Servers and this fixed the problem
nameserver 61.9.211.33
nameserver 61.9.211.1