Chapter Nineteen

Troubleshooting the Network

Objectives

• To learn a systematic troubleshooting method

• To examine some basic necessities for troubleshooting

• To examine some common OS problems and their solutions

The Basic Troubleshooting Tools

• Boot diskettes for different OSs

• A recovery CD for the 32-bit OSs

• Some basic diagnostic utilities

• A toolkit

• A basic clue about what you’re doing

Creating a Boot Diskette in WIN9x

• Have one blank formatted high-density 3.5” floppy diskette.

• Have the WIN9x Installation CD.

• Click Start>Settings>Control Panel.

• Double-click on Add/Remove Programs.

• Click Create Disk Button.

• Follow the yellow brick road.

Key Files of the WIN9x Boot Disk

– IO.SYS:– MSDOS.SYS– DRVSPACE.BIN– CONFIG.SYS– HIMEM.SYS– COMMAND.COM

– AUTOEXEC.BAT– OAKCDROM.SYS– RAMDRIVE.SYS– EXTRACT.EXE– FDISK.EXE– SYS.COM– FORMAT.COM:

Installation Diskette Set for NT

• Have three blank, formatted high-density 3.5” diskettes and the installation CD.

• On the CD, browse to the i386 directory.

• Type WINNT /OX and follow the instructions.

Installation Diskette Set for WIN2K

• Have three blank, formatted high-density 3.5” diskettes and the Installation CD.

• On the CD, browse to the BOOTDISK directory.

• Type MAKEBOOT at the command prompt.

• Follow the yellow brick road.

Key Files for Booting NT, 2K, or XP

• NTLDR

• NTDETECT.COM

• BOOT.INI

• NTBOOTDD.SYS

• OSLOADER.EXE

• HAL.DLL

Creating an ERD in WINNT, 2K, or XP

• From the command prompt or from the Run line, type RDISK.EXE.

• Insert disk and sit back.

• Any time device drivers are changed or new users are added, a new ERD should be made.

When the System Fails to Boot

• Invalid boot disk

• Inaccessible boot device (or boot device not available)

• I/O error reading Drive C:

• Missing NTLDR

• Bad or missing command interpreter

Possible Boot Failure Solutions

• Check BOOT.INI– Are we pointing to the right drive?

• Are you using a third party disk controller?– Try reinstalling the drivers and check cables.

• Is the disk recognized by the system?– Run setup and see if the CMOS sees it.

More Boot Errors

• Error in CONFIG.SYS line XX

• HIMEM.SYS not loaded

• Missing or corrupt HIMEM.SYS

• Device/service has failed to start

Solutions to These Problems

• Rename CONFIG.SYS to CONFIG.BAK and reboot.– Windows does not require these.– If the machine boots fine now, look for errors in

CONFIG.SYS.

• Do the same with AUTOEXEC.BAT.

Advanced Startup Options

• 1. Normal

• 2. Logged (\BOOTLOG.TXT,

• 3. Safe mode

• 4. Step-by-step confirmation

• 5. Command prompt only

• 6. Safe mode command prompt only

Normal

• Uh, gee, Mom. What’s that?

• Sometimes after an unexpected shutdown, you’ll get the advanced start menu by default.– You know you kicked the power cord out by

accident, so there’s no reason to go into a different mode.

Logged

• As the machine boots the next time around a text file is generated of each driver and service that attempts to load.

• The BOOTLOG.TXT file in the root directory will tell you what services started and what ones didn’t.

Safe Mode

• It is a technician’s best friend.

• It only loads a basic set of Windows drivers.

• Problematic drivers can be removed and/or reloaded and the machine restarted.

• Ghosts in the machine can be sorted out from here.

Step by Step Confirmation

• Each line in CONFIG.SYS and AUTOEXEC.BAT is listed and you choose whether to load them or not.

• Windows ignores these lines anyway, but go ahead and have fun if you like.

Command Prompt Only

• Loads only a basic DOS prompt without any superfluous drivers used only in graphical mode

• Good for running old DOS programs that don’t get along with Windows

• Good for troubleshooting file system issues

Command Prompt Safe Mode

• If this is the only way your system boots, it will probably be necessary to reinstall Windows.– BUT -- you can access the drives and files from

here and back up critical files.

Troubleshooting Network Issues

• Blinky lights– Lights on NICs, hubs, and switches indicate

connectivity.– Green is good; amber means they see each

other, but can’t talk. – No light is REAL bad.

Ping

• Successfully pinging an IP address, but failure to ping a computer name means DNS isn’t working.

• Failure to ping an IP address (assuming connectivity) means TCP/IP isn’t working.– Usually a configuration issue

• Failure to ping 127.0.0.1 means the NIC isn’t working.

Device Manager

• A yellow exclamation point next to the NIC indicates the device is recognized but the driver or configuration is invalid.

• A red X means that a driver is loaded for that device but Windows doesn’t see it.

IPCONFIG

• If the IP address reads 0.0.0.0, the NIC is not configured at all.

• If the IP address reads 169.x.x.x, the NIC is working, and is configured for DHCP, but a DHCP server isn’t being found.