I have just upgraded from 10.04 to 12.04. I didn't notice the problem at first. But when installing horde with the pear installer it failed to download all of the packages.

So I did a little hunting and realised not all hosts are reachable:

Ping google.com

 root@sub:~#  ping google.com
 PING google.com (74.125.132.113) 56(84) bytes of data.
 64 bytes from wb-in-f113.1e100.net (74.125.132.113): icmp_req=1 ttl=51 time=11.1 ms
 64 bytes from wb-in-f113.1e100.net (74.125.132.113): icmp_req=2 ttl=51 time=11.1 ms
 --- google.com ping statistics ---
 2 packets transmitted, 2 received, 0% packet loss, time 1002ms
 rtt min/avg/max/mdev = 11.166/11.177/11.188/0.011 ms

Ping cnn.com

root@sub:~# ping cnn.com
PING cnn.com (157.166.255.18) 56(84) bytes of data.

--- cnn.com ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1006ms

At first I could not reach any hosts so I added nameserver 8.8.8.8 to my /etc/resolv.conf file. This was blank after the upgrade.

So why can i not ping ccn.com and other random domains but I can google.com?

up vote 4 down vote accepted

That's because CNN blocks ICMP-Echo-Request packets and Google doesn't, which makes ping not work. Ping is no longer a reliable reachability test for Internet hosts due to the number of firewalls that block all ICMP traffic as a risk-vector.

  • Thanks very much, this has cleared it up for me :) why o why did I have to pick cnn as a test domain ;) – Miss Tina Mar 31 '13 at 23:34

Not all addresses return pings. Since you can ping google.com, you do have connectivity to the internet. Not having a nameserver in /etc/resolv.conf was probably the problem you had at first.

If you want to check connectivity to ccn.com, you will have to browse there, or do a wget.

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