host name look up on ip address

Hi,

I am trying below example.
http://www.avajava.com/tutorials/lessons/how-do-i-use-a-host-name-to-look-up-an-ip-address.html

I wonder why got out put 5 different times as below

--------------------------
Which Host:local host
Canonical Host Name:DERBIZZ
Host Name:DERBIZZ
Host Address:192.168.1.106
----------------------------------------------------
Which Host:www.google.com
Canonical Host Name:po-in-f104.google.com
Host Name:www.google.com
Host Address:72.14.253.104
----------------------------------------------------
Which Host:www.google.com #1
Canonical Host Name:po-in-f104.google.com
Host Name:www.google.com
Host Address:72.14.253.104
--------------------------
Which Host:www.google.com #2
Canonical Host Name:po-in-f103.google.com
Host Name:www.google.com
Host Address:72.14.253.103
--------------------------
Which Host:www.google.com #3
Canonical Host Name:po-in-f99.google.com
Host Name:www.google.com
Host Address:72.14.253.99
--------------------------
Which Host:www.google.com #4
Canonical Host Name:po-in-f147.google.com
Host Name:www.google.com
Host Address:72.14.253.147

what is difference between cononical host name and host name.

Just as an aside, what happens if we try doing a lookup on a host that doesn't exist, such as: InetAddress.getByName("www.this-host-does-not-exist.com")? An UnknownHostException is thrown, as shown below.

java.net.UnknownHostException: www.this-host-does-not-exist.com: www.this-host-does-not-exist.com

what is the meaning of host not exists.

please advise
Any links resources ideas highly appreciated. Thanks in advance