Networked and non-networked situations differ drastically
Networked situations add complexity
Router or switch CPU1 Print server If a user can’t print from CPU1, it could be due to many possible problems on the network. Networked printer X X X X X X X
Verify the symptom
Talk with the user to try to get a precise description of the symptoms
When did it happen?
Does it happen during boot, when the OS loads, or after the system has been running for a while?
What has changed?
Try to find out if anything has changed
Even recent changes before the problem began occurring
Check the environment
Heat, humidity, dirt
What OS? What applications? Do others use the computer?
Reproduce the problem
If a problem happens only once, it’s not a problem
Otherwise, try to make the problem happen again
Isolate the symptom
Hardware—remove suspect parts
Software—remove background programs or boot into Safe Mode
Separate hardware from software
Replace the suspect hardware with known good hardware
Uninstall the suspect software and reinstall it
Install the latest patch or upgrade
Check for viruses
Use search engines on the Internet
Make the fix and test
Keep track of what you did so you may return to the previous state if the fix does not work
OSI Seven-Layer Model
Use as a guide in troubleshooting
Layer Number Name Description Layer 1: Please Physical NICs (link light), cables, switches, hubs, etc. 1s, 0s Layer 2: Do Data Link MAC addresses and CSMA/CD Layer 3: Not Network IP operates here Layer 4: Throw the Transport TCP/UDP operate here Layer 5: Sausage Session Manages connections Layer 6: Pizza Presentation Describes how to present data Layer 7: Away Application Interacts with user
Mike’s Four-Layer Model
Check the hardware starting with the physical layer