CHAPTER 7

NETWORKTROUBLESHOOTING

7.1 BASIC TROUBLESHOOTING METHODOLOGY

-TROUBLESHOOTING-Process of identifying, locating and correcting problems that occur.

• There are structured techniques that can be used to determine cause & problems

• When troubleshooting, proper documentation must be maintained

• The problem encountered

• Steps taken to determine the cause of the

problem • Steps to correct

the problem and ensure that it

will not reoccur

This documentation should include as much information as possible about:

7.1.1 Steps Involved in Basic

Troubleshooting Methodology

Steps for troubleshooting network problems :-

• Identify the symptoms and problems

Record what you learn from people or systems that alerted you to the problems and keep that documentation handy.

Cont’d

• Identify the affected area.

Are users across the entire network experiencing the problem at all times? Or, is the problem limited to a specific geographic area of the net- work, to a specific demographic group of users, or to a particular period of time? Are all of the symptoms related to a single problem, or are you dealing with multiple problems?

• Determine what has changed.

Recent hardware or software changes could be causing the symptoms.

Cont’d

•Establish the most probable cause.

Do the following steps:-1. Verify user competency. 2. Re-create the problem, and ensure that you can reproduce it

reliably. 3. Verify the physical integrity of the network connection (such

as cable connections, NIC installations, and power to devices), starting at the affected nodes and moving outward toward the backbone.

4. Verify the logical integrity of the network connection (such as addressing, protocol bindings, software installations, and so on).

•Determine whether escalation is necessary.#

If a problem appears to affect a large group of clients and you suspect a router is involved, for example, you might need to contact one of the engineers responsible for maintaining routers

on your network.

• Create an action plan and solution and be prepared for all potential

effects.

For example, if you have to reassign IP addresses, how will the change of an IP address on a server affect its clients? Or, in another case, if you upgrade the type of client software used on a workstation, how will that affect a user’s daily routine?

•Implement the solution and test the result.

Has your solution solved the problem?

•Identify the results and effects of the solution.

For example, if you had to replace a switch, did the new switch affect network performance, VLAN status, or client access to the network?

•Document the solution and process.

• Make sure that both you and your colleagues understand the cause of the problem and how you solved it. This information should be kept in a centrally available repository, such as an online databa

7.1.3.Assess Common

Physical Problems in Network

The Sense of Sight

Vision is used to detect problems such as improperly connected or poorly constructed cable, including:1. Cables which are not connected 2. Cables connected to the wrong port3. Loose cable connection .4. Damage cables and connectors

The Sense of Smell

Smell can alert which components are overheating. The smell of burning components is very

distinct and is a sure sign that something is seriously wrong

The Sense of Touch

• Trouble-shooter can use touch to feel for overheated components as well as to detect mechanical problems with devices such as cooling fans.

These devices usually create a small vibration in the component that can

be detected using touch.

The Sense of Hearing

• Hearing is used to detect major problems such as electrical issues

and the proper operation of cooling fans and disk drives.

• All devices have characteristics sound

• Any change from the normal sounds usually indicate a problem of some

sort.

Software Utilities for Troubleshooting Connectivity

• A number of software utility programs are available that can help identify network problems. Most of these utilities are provided by the operating system as command line interface (CLI) commands. The syntax for the commands may vary between operating systems.

• Some of the available utilities include: 1. ipconfig - Displays IP configuration information2. ping - Tests connections to other IP hosts 3. tracert - Displays route taken to destination 4. netstat - Displays network connections 5. nslookup - Directly queries the name server for information

on a destination domain

QUESTIONS ?

1. Which of the following is NOT the software utilities for troubleshooting connectivity A. IpconfigB. PingC. zennonD. Nslookup

2. Which statement should NOT be included in the documentation for troubleshooting process?

A. Initial problemB. Final problem resolutionC. Test the connections to other IP hostsD. Preventive measures

3. What process involves in troubleshooting?

A. Identifying, locating & correcting problems

B. Identifying, locating & RestartC. Test connection D. Restart & Test Connection

4. Give the function of TRACERT?A.Displays IP configuration

informationB. Displays route taken to

destinationC. Displays network connectionsD.Test connection to other IP hosts

5. Assess Common Physical Problems in Network involves :

A. Overload connectionB. Wrong IP AddressC. Sense, Smelling, Sight, ListeningD. Make an observation

6. Give the function of NSLOOKUP?

A. Directly queries the name server for information on a destination domainB. Displays route taken to destinationC. Displays network connectionsD. Test connection to other IP hosts

Thank You