Is this bad
 

every time I go to the commad prompt it says "root@host3-null root" whats up with the null root and every time I restart when my computer boots up it says an error and my linux will not act right.

So please help me... Thanks in Adv ...

Could we have more information, please.

What is the error message?
What distribution are you running?
How long has this been happening?
What did you do right before it happened?

red hat 7.3
ever since I connected it up to my switch that gives access to my dsl line
I just hooked it up to the dsl line
and I have to reboot my system to see the whle error message

It is likely to be picking up the host name from your dsl connection. Mine does that and I have to rename it either when I reinstall (for whatever reason) or manually. Do a search for changing the hostname on this site.

how do I search for files

post your /var/log/message so we can see if there's any error messages in regards to your networking.

also, like suggested, look into the host name thing. in rh 7.3, according to red hat, you need to edit 2 files: /etc/hosts and /etc/sysconfig/network. my computer's name i gave it is tron and this is what my 2 files look like.

/etc/hosts:
/etc/sysconfig/network

how do I do that how do i find that file and how do I search for files

not hard at all. the easiest way to explain it is to open up a shell terminal and use the following commands:

1. su
<enter root password>
2. kwrite /etc/hosts
<edit file, save it, exit out of kwrite>
3. kwrite /etc/sysconfig/network
<edit file, save it, exit out of kwrite>

since changing these files requires a reboot, you can use this command so you don't have to reboot.

4. hostname your_name_choice_for_your_computer

there's a number of ways to find files (even though i already gave you the fully qualified filepaths to the files).

1. locate name_of_file
2. whereis name_of_executable_file
3. find directory_to_search_in -name name_of_file

I have a Dlink Di 701(res. gateway) aka fire wall)
and a switch my domain name is domain and my device name is my last name and my Ip address that it's giving the computer is the windos default Ip address which is 192.168.*.* so I don't know if that help but there it is

I type su and it doen't do any think it does'nt ask for or prompt fora password

sounds like you're already logged in as root, so you won't need to give it a password, nor would you need to su since being logged in as root already gives you full access to all the files on your computer. don't log in as root this way!

I'm still mystified as to what the actual problem is. What is it that's wrong that you want to fix?