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In this lesson, we're going to discuss

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how you can understand the troubleshooting process

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by walking through an example of an issue

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that you may experience as a network technician

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or administrator.

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We're going to take this step by step

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and walk through all seven portions

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of these steps in order in just a few minutes.

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Now, the first step is to identify the problem.

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So let's pretend you're working

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at the help desk and a user reports

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that they have intermittent network connectivity issues.

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Now, as you start working with this person,

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you're gathering information, you're questioning the user,

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and you're trying to identify the symptoms.

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When you ask the user questions,

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they tell you that based on their observations,

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it seems that the connection is dropping

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and then resuming sporadically.

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And they tell you that there's no rhyme or reason.

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It's happening at all times of the day,

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no matter what program they're using.

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So we really don't know what's causing it yet,

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but we're going to gather as much information as we can.

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We'll ask them additional questions,

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we'll identify those symptoms,

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and we're going to ask things like, has anything changed,

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and can we duplicate the problem?

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Also, we're going to approach multiple problems individually,

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even if we have multiple users calling up

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and telling us they're all having the same issue.

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It's important to note

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that there are multiple people having this issue,

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but we're going to treat each individual user

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as their own ticket and their own problem

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because each one may be caused by different issues.

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This brings us to our second step.

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We now need to establish a theory of probable cause.

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So here we're going to think to ourself,

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what could be causing this issue?

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Why is this connection sporadically dropping and resuming?

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Well, it could be a faulty router.

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It could be that your bandwidth is overloaded.

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It could be there's an IP conflict.

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It could be the switchboard is failing on the router.

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It could be a faulty cable.

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There are lots and lots of different things,

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but our goal here is to establish

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a theory of probable cause.

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And when we do this, we are going to question the obvious,

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and we're going to consider different approaches

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such as the top-to-bottom approach,

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the bottom-up approach, or the divide and conquer approach.

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Now, because we're having an issue

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with intermediate network connectivity,

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we might want to go ahead and do this from the bottom up.

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And the bottom up would be starting with the physical layer.

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So if this is a wireless connection,

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we might want to see is there any wireless frequency issues

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that are causing this connection to drop?

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If it's a cabling issue, we may want to check the cable

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and verify it's working correctly.

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Now, at this point in step two,

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we're not going to take the actual actions yet.

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We're just coming up with the idea

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of what we think the probable cause is,

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and then we move into step three.

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So let's move into step three,

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and we're going to test the theory to determine the cause.

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Here, we need to go ahead and test this theory

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and see is this theory correct, and if it's confirmed,

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then we would figure out what steps

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we need to do to resolve the issue.

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If it's not correct and we've ruled it out,

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then we need to come up with a new theory,

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and we'll start this process again by going back to step two

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and then into step three again.

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So in our case,

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let's say that we believe it was an issue with the router,

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so we're going to go ahead and test the router,

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and we're going to check its logs and reboot it.

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At this point, we've done that and we see if it works.

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Nope, we're still getting sporadic issues

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with the connectivity.

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All right, in that case, we'll move back to step two,

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establish a new theory of probable cause.

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In this case, we're going to think it's overloaded bandwidth.

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So we go into step three,

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and we test our theory by monitoring bandwidth usage

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to rule out if it's overloaded or not.

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In this case, we look at our bandwidth and it looks normal.

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It's all within our normal bands and tolerances.

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So we go back to step two and we go ahead

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and think of another probable cause.

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Well, if it keeps dropping network connectivity

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and then it resumes itself automatically,

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maybe it's an IP conflict.

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So I'm going to go into step three and test my theory,

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and I'm going to go ahead and scan the network

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to see if anybody else is using that IP address.

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And if we're using DHCP,

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I'm going to see if that DHCP address

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is being handed out to multiple people.

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At this point, let's say that was the issue.

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So now that we know that's the issue,

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we have to establish a plan of action.

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And this brings us to step four.

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In step four, we're going to establish a plan of action

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to resolve the problem and identify potential effects.

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Now, when we do this, we are going to go ahead

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and figure out what is causing this IP conflict.

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Maybe we're using static IP addresses

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and somebody isn't doing proper IP management.

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Or maybe it's a problem with the DHCP server.

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In either case, we have to establish what our plan is,

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and then we're going to go about fixing that plan in step five.

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So for this case, let's go ahead

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and say it was an issue with our DHCP server.

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So we come up with a plan to go ahead

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and troubleshoot that DHCP server to reconfigure it

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and to change our scope addresses inside the DHCP server.

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This now brings us to step five,

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which is to implement the solution or escalate as necessary.

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In this case,

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if I have permission to do that change on the DHCP server,

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I can implement that change.

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But if I don't, I'm going to have to escalate that

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to the change advisory board for their approval

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for us to make a change to the DHCP server

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and to the technicians who are responsible

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for that DHCP server.

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When we get into step six,

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we need to verify full system functionality

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and implement preventive measures if applicable.

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So let's say that the DHCP server had a configuration issue,

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we got permission to make the change,

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we implemented that change.

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Now, we want to see does this solve the problem?

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And when we look at it, we figure out that, yes,

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it does solve the problem.

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We've verified full system functionality,

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everybody's getting the proper IP addresses

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and everyone is happy.

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The only problem is we figured out the issue was,

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somebody went in and made a configuration change

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to the DHCP server without permission and without going

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through the configuration management process.

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Now, we have a preventative measure

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that we need to implement.

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And here we're going to work within the bounds

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of our organizational structure to figure out

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how do we implement preventative measures.

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In this case,

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it's probably going to involve talking with your manager,

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and having your manager talk with the technician

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who made the unauthorized change

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to ensure that doesn't happen again in the future.

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And then we go into our seventh step,

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which is to document our findings, actions, outcomes,

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and lessons learned throughout the process.

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As we're going through and doing all these different steps,

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we are going to be documenting this

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inside of our trouble ticket system

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so we know exactly what's going on.

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And if you go home for the day

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and this is still an issue,

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somebody else can come in behind you

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and start working on this issue too.

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So as you're doing this,

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we want to record the issue symptoms we gathered in step one.

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We want to talk about the different theories we had.

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We want to talk about what the diagnostic steps

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and tests were in step three,

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where we're testing our theory to determine the cause.

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We want to talk about the solution that we came up with

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and how it worked when we tried to implement it.

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And then we want to talk about the outcome

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and what changes we made,

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and what we're now seeing as a result of those changes.

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All of these are things that we want to document

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inside our trouble ticket system

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and in some cases in our lessons learned system too,

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so we can then share these lessons with other people.

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That's the idea of how you work

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through this troubleshooting methodology methodically,

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going from step one down to step seven

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by identifying the problem,

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establishing a theory of probable cause,

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testing the theory to determine the cause,

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establishing a plan of action to resolve the problem

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and identify potential effects,

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implement the solution or escalate as necessary,

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verify full system functionality

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and implement preventative measures if applicable.

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And then finally document findings, actions, outcomes,

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and lessons learned throughout the process.