Summary

A problem that seems insurmountable can become easier to solve if you break it down into smaller parts. Problems tend to be split in two ways: by location or by component (whether it’s software or hardware).

Although networks are complex and dependent systems, where one failing component can make it seem like everything has failed simultaneously, typically there’s only one problem causing a domino effect. The divide-and-conquer method allows you to find the problem component without knowing why it’s causing a failure. When you have large numbers of components or locations involved, divide-and-conquer troubleshooting (also known as a binary search) can change your number of guesses from millions to dozens, thus saving you a lot of time.

Although the divide-and-conquer method isn’t always the end-all and be-all of the troubleshooting process, it’s still a powerful method that can usually pinpoint a culprit in most situations.

Workshop

Q&A

Q Why should I perform divide-and-conquer troubleshooting on my six-node network? It only takes me six guesses to find any problem!

A You’re right. Obviously, using the divide-and-conquer method with small numbers might seem more trouble than it’s worth. However, you may end up solving the problem in fewer than six guesses.

Q If my router port is having problems, won’t it seem like the whole network is down?

A Yes, if you have no local servers. In this case, you can try to contact workstations on your physical segment—this will rule out the physical segment. (For users of Windows 95 file and printer sharing for Microsoft Networks, try to find someone whose CD-ROM or printer is shared. If you have TCP/IP installed, try to ping another workstation on the network—if you can, the network is definitely not down.)

Q Although I’m having some problems on my workstation, the divide-and-conquer method is problematic for me. I can’t get rid of everything in my Startup folder; otherwise, I won’t be able to work. Any other suggestions?

A Each situation is obviously different. The divide-and-conquer method might not be your best strategy here. Instead, you may need to ask, “Which of these things is not like the other?” For more information on this troubleshooting strategy, see the next hour.

Quiz

1.  The divide-and-conquer troubleshooting strategy enables you to do what?

A.  Mathematically calculate a problem resolution

B.  Solve any problem in the world by performing a binary search

C.  Locate a problem by splitting the problem area in half (or removing half of the components involved)

D.  Divide the problem-solving labor among several people

2.  You’re thinking of a number from 1 to 500. What might my second guess be?

A.  25

B.  250

C.  300

D.  125

3.  What’s the first thing you should determine when hearing of a network problem?

A.  Determine whether the problem exists for one user or for multiple users.

B.  Check the router.

C.  Check the documentation.

D.  Determine whether the server has crashed.

4.  You track a network problem down to the hub that the segment’s router is on. What do you do next?

A.  Start port-level divide-and-conquer proceedings.

B.  Remove the router from the network.

C.  Start to check the router documentation.

D.  Remove the hub from the rest of the network.

5.  You’ve tracked down a problem to a Windows 95 PC, but you have no idea where the problem might be. How do you perform a “vanilla boot”?

A.  By pressing F8 upon bootup and then choosing Safe Mode.

B.  By pressing F5 upon bootup and then choosing Safe Mode

C.  By pressing F8 upon bootup and then choosing Divided Mode

D.  By pressing F5 upon bootup and then choosing Divided Mode

Answers to Quiz Questions

1.  C

2.  D

3.  A

4.  A

5.  A