I have a trouble with connecting to the internet from the Solaris UNIX.

I posted once a thred "Setting a DHCP client under Solaris" and got the following answear:
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cat /dev/null > /etc/hostname.XXX
cat /dev/null > /etc/dhcp.XXX
where XXX is the name of the network interface like hme0, qfe0, eri0, ce0, bge0 or something like that..
after you are done with that simple reboot or issue the following command to make the change right away if you cant reboot
ifconfig XXX dhcp start
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I tried that and:

-My Hostname changed to 'Unknown'!
-I can't view any website with wy browser (Netscape)

Here is what the computer says:
(My network interface = rf0)
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Sun Microsystems Inc. SunOS 5.9 Generic January 2003
# ifconfig -a
lo0: flags=1000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
rf0: flags=1004843<UP,BROADCAST,RUNNING,MULTICAST,DHCP,IPv4> mtu 1500 index 2
inet 80.83.34.2 netmask fffff800 broadcast 80.83.39.255
ether 0:40:f4:54:9b:b4
# ifconfig rf0 dhcp status
Interface State Sent Recv Declined Flags
rf0 BOUND 2 1 0 [PRIMARY]
(Began, Expires, Renew) = (08/24/2004 18:59, 08/24/2004 20:34, 08/24/2004 19:46)
#
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How can I connect to internet from Solaris 9 x86. (I used Windows to post this thred...)?
How to change my hostname. It sets itself to 'unknown' every time I start the system?

If you know the answear please help!