need help with network

I have a computer lab with 28 computers. For some reason 2 of my computers cannot conect to the network. I get an error message 'cannot find server'. I am sorry but when it comes to networking i am still learning. These computers were working fine the day before, now its like the network is just not there. I have no idea what to check or look for. Can anyone please help me? I have no idea as to what info you would need to help me so please let me know.

Thanks
Sinjun
sinjunAsked:
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AndreLauzonConnect With a Mentor Commented:
Go by halfes,

Plug a working PC, one that currently has network acces, into the RJ-45 wall plug of a defective PC.

If that station has network acces then your problem lies on this side of the wall, if not check your cabling up to your patch panels or hubs (plug in a laptop at the other end and see if you can ping the workstation)

If they can ping each other try plugging your cable into a different port on your hub and retry test #1.

If, on the first test you DID have network acces, check the cable between the wall and the defevtive PC.

If thats ok, check your TCP/IP settings, especialy the Subnet mask, try installing a new network card in the defective PC.

Now for a long shot:

Is one of your problems PCs a recent purchase ?
Do they have acces when only 1 is turned on ?

if so take a look a your network cards MAC adresses, there 'supposed' to be unique to each card but check it anyway (I've had this experience and both PCs lost network connectivity)

Good luck.
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papercertCommented:
It is best to troubleshoot from the bottom of the OSI model, up to the top.  Therefore, the first thing to do is check the physical connectivety.  Make sure that the network cables are connected at both ends (PC and switch/hub).  Once that is done, ensure that you have a link light at both NICs.  Once your satisfied that everything is connected properly, test the machines to verify if they can see the network.  If so, then your all set.  If not, post you network configuration below, be sure to include all protocol info, as well as OS.

GOOD LUCK!
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gibsonpd3620Commented:
1.  Use a cable from one of the computers that is working.  If the computer can connect, you have a bad cable or port.
2.  Boot up the computer, right click Network neighborhood and choose properties from the drop down menu.  Check the settings against those with a working station.
3.  Check your DHCP server to insure that you have enough IP addresses available for all of the computers.

This should be a good start.
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adownsCommented:
First thing I would do it plug the network cable from one of the problem computers into a known working jack and reboot. Take notice if the link light on the back of the network card lights when you unplug it and plug it into another jack. If the light is not on when its plugged into the problem jack it is a wiring problem.
If the computer still does not get on the internet plugged into a working jack then I would check the settings as gibsonpd3620 stated in the last comment.
If the Computer can connect then it is a problem with the hoizontal cabling to the wiring closet or rack.
If all else fails I'd reinstall the card or replace it.
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sinjunAuthor Commented:
papercert, dont take this the wrong way but can you speak a little less technical?
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papercertCommented:
Sure, basically... make sure you've got a green light on network card of both computers.  If you don't then check you network cables and make sure that they are connected properly.  LOL
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sinjunAuthor Commented:
O.k. The cables are good. I've checked the settings and there good. I cant check the network properties; it says unable to browse network. One comp. has all the correct settings, the cable is good, the card is good (lights are on) I've checked everything and still no good.
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3408Commented:
I usually start with doing a ping to another pc (command box -> ping <IP address> -l 1500 ).
If you get a reply, your "network" is ok; meaning that your network devices are working and the IP stack is correct (99% of time). It also means that you should check your windows configuration.
If you don't get a reply: check your cabling/hub/switch/router/nic (don't forget autosensing).

Start with this and give us the result!

3408
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