1 1 00:00:00,630 --> 00:00:02,960 Network troubleshooting methodology. 2 2 00:00:02,960 --> 00:00:04,640 In this lesson, we're going to discuss 3 3 00:00:04,640 --> 00:00:07,640 the official CompTIA Network troubleshooting methodology. 4 4 00:00:07,640 --> 00:00:09,410 This is the first thing that we need to cover 5 5 00:00:09,410 --> 00:00:10,840 in this overall section, 6 6 00:00:10,840 --> 00:00:12,920 on troubleshooting physical networks. 7 7 00:00:12,920 --> 00:00:15,730 Now we're going to cover domain five network troubleshooting, 8 8 00:00:15,730 --> 00:00:19,560 specifically objectives, 5.1 and 5.2 in this section. 9 9 00:00:19,560 --> 00:00:21,900 Objective 5.1 states that you must explain 10 10 00:00:21,900 --> 00:00:23,540 the network troubleshooting methodology, 11 11 00:00:23,540 --> 00:00:25,930 which we're going to fully cover in this lesson. 12 12 00:00:25,930 --> 00:00:27,920 Then in this section, we're going to move through 13 13 00:00:27,920 --> 00:00:29,960 and talk about objective 5.2, 14 14 00:00:29,960 --> 00:00:31,540 which states that given a scenario, 15 15 00:00:31,540 --> 00:00:34,260 you must troubleshoot common cable connectivity issues 16 16 00:00:34,260 --> 00:00:36,000 and select the appropriate tools. 17 17 00:00:36,000 --> 00:00:37,510 We're going to spend the rest of this section 18 18 00:00:37,510 --> 00:00:39,800 focused on that objective, but for now, 19 19 00:00:39,800 --> 00:00:40,920 let's focus our attention 20 20 00:00:40,920 --> 00:00:43,030 on the network troubleshooting methodology. 21 21 00:00:43,030 --> 00:00:45,440 After all, much of your day as a network technician 22 22 00:00:45,440 --> 00:00:47,240 is going to be spent entering trouble tickets 23 23 00:00:47,240 --> 00:00:50,360 or fixing problems that are found inside of your networks. 24 24 00:00:50,360 --> 00:00:52,210 To help us with this, we have a seven-step 25 25 00:00:52,210 --> 00:00:53,980 troubleshooting methodology that we can use 26 26 00:00:53,980 --> 00:00:56,480 to solve any problem inside of our network. 27 27 00:00:56,480 --> 00:00:57,970 There are seven steps here, 28 28 00:00:57,970 --> 00:00:59,970 the first is to identify the problem. 29 29 00:00:59,970 --> 00:01:02,580 Second, establish a theory of probable cause. 30 30 00:01:02,580 --> 00:01:05,050 Third, test the theory to determine the cause. 31 31 00:01:05,050 --> 00:01:07,740 Fourth, establish a plan of action to resolve the problem 32 32 00:01:07,740 --> 00:01:09,400 and identify potential effects. 33 33 00:01:09,400 --> 00:01:12,600 Fifth, implement the solution or escalate as necessary, 34 34 00:01:12,600 --> 00:01:16,370 sixth, verify full system functionality and if applicable, 35 35 00:01:16,370 --> 00:01:17,890 implement preventative measures, 36 36 00:01:17,890 --> 00:01:20,910 and seventh, document findings, actions, outcomes, 37 37 00:01:20,910 --> 00:01:22,180 and lessons learned. 38 38 00:01:22,180 --> 00:01:24,680 All right, let's take a look at each of these seven steps 39 39 00:01:24,680 --> 00:01:26,130 in a little bit more depth. 40 40 00:01:26,130 --> 00:01:28,420 Step one, identify the problem. 41 41 00:01:28,420 --> 00:01:31,080 This is our first step in the troubleshooting process, 42 42 00:01:31,080 --> 00:01:33,730 and it's used to clearly understand what the issue is 43 43 00:01:33,730 --> 00:01:35,160 that you're trying to solve. 44 44 00:01:35,160 --> 00:01:37,750 This problem may have been reported to you by an end user, 45 45 00:01:37,750 --> 00:01:40,230 an administrator or through some automated alert. 46 46 00:01:40,230 --> 00:01:41,190 It really doesn't matter, 47 47 00:01:41,190 --> 00:01:43,090 whatever the original report method used, 48 48 00:01:43,090 --> 00:01:45,350 your goal now is to get more information 49 49 00:01:45,350 --> 00:01:47,200 so you can fully understand that issue 50 50 00:01:47,200 --> 00:01:50,190 that you're trying to solve and get things back to normal. 51 51 00:01:50,190 --> 00:01:51,950 As we attempt to identify the problem, 52 52 00:01:51,950 --> 00:01:53,780 we have to gather additional information, 53 53 00:01:53,780 --> 00:01:56,140 question our users, to gather more details, 54 54 00:01:56,140 --> 00:01:58,630 identify symptoms of the issue and determine 55 55 00:01:58,630 --> 00:01:59,950 if anything has changed. 56 56 00:01:59,950 --> 00:02:02,210 Then we're going to try to duplicate or reproduce 57 57 00:02:02,210 --> 00:02:04,730 the problem if possible, sometimes though, 58 58 00:02:04,730 --> 00:02:07,380 you may have multiple problems occurring at the same time. 59 59 00:02:07,380 --> 00:02:09,310 And if this is the case, you should approach 60 60 00:02:09,310 --> 00:02:11,070 each of those problems individually 61 61 00:02:11,070 --> 00:02:13,490 and not bundle them together as a single problem 62 62 00:02:13,490 --> 00:02:15,400 or shared problem, unless you figure out 63 63 00:02:15,400 --> 00:02:16,730 that they are clearly linked, 64 64 00:02:16,730 --> 00:02:19,210 because sometimes they're not clearly linked. 65 65 00:02:19,210 --> 00:02:21,110 All right, let's take a look at what this might look like 66 66 00:02:21,110 --> 00:02:22,290 in the real world. 67 67 00:02:22,290 --> 00:02:24,140 Let's pretend you're sitting at the service desk 68 68 00:02:24,140 --> 00:02:25,807 and an end user calls up and states, 69 69 00:02:25,807 --> 00:02:27,677 "The internet is down, the internet is down. 70 70 00:02:27,677 --> 00:02:30,580 "I can't do anything right now, I need your help." 71 71 00:02:30,580 --> 00:02:32,040 Well, what are you going to do? 72 72 00:02:32,040 --> 00:02:33,960 As a network technician, you probably know 73 73 00:02:33,960 --> 00:02:35,960 the internet is not down completely, 74 74 00:02:35,960 --> 00:02:38,430 but it's really just a problem with a user's connection 75 75 00:02:38,430 --> 00:02:41,070 to the internet that may be slow, unresponsive, 76 76 00:02:41,070 --> 00:02:42,640 or simply not connected. 77 77 00:02:42,640 --> 00:02:44,860 But maybe the user was trying to open Facebook 78 78 00:02:44,860 --> 00:02:46,730 and they got an error message and told them 79 79 00:02:46,730 --> 00:02:48,160 there is no internet connection, 80 80 00:02:48,160 --> 00:02:51,230 so to them, the internet is down, but we all know 81 81 00:02:51,230 --> 00:02:53,000 the internet is made up of millions of different 82 82 00:02:53,000 --> 00:02:55,440 computer networks, and the chances of the entire internet 83 83 00:02:55,440 --> 00:02:57,720 being down is pretty darn slim. 84 84 00:02:57,720 --> 00:02:59,730 So what are you going to do about this? 85 85 00:02:59,730 --> 00:03:02,140 Well, first you should ask some additional questions 86 86 00:03:02,140 --> 00:03:04,040 to the user, let's ask them things like, 87 87 00:03:04,040 --> 00:03:05,760 what were you doing at the time of the error, 88 88 00:03:05,760 --> 00:03:08,260 or what websites are you trying to access? 89 89 00:03:08,260 --> 00:03:10,510 As you ask them questions, you might also ask 90 90 00:03:10,510 --> 00:03:11,760 what type of connection they have. 91 91 00:03:11,760 --> 00:03:14,380 Are they using a wired connection, wifi, cellular 92 92 00:03:14,380 --> 00:03:16,040 or something else entirely. 93 93 00:03:16,040 --> 00:03:18,600 As you ask more questions, you're gaining more information 94 94 00:03:18,600 --> 00:03:20,470 and this can help you identify the symptoms 95 95 00:03:20,470 --> 00:03:22,750 and determine if anything has changed. 96 96 00:03:22,750 --> 00:03:25,090 For example, you might ask, when was the last time 97 97 00:03:25,090 --> 00:03:26,500 you connected to that website? 98 98 00:03:26,500 --> 00:03:29,040 And if their answer was an hour ago, then you should ask, 99 99 00:03:29,040 --> 00:03:31,040 did you install, remove any programs since then, 100 100 00:03:31,040 --> 00:03:33,760 or has anything changed in the last hour? 101 101 00:03:33,760 --> 00:03:35,680 As you gather more information, it's going to help you 102 102 00:03:35,680 --> 00:03:37,290 figure out what's going on. 103 103 00:03:37,290 --> 00:03:39,130 All of this falls under that first step 104 104 00:03:39,130 --> 00:03:40,820 of identifying the problem. 105 105 00:03:40,820 --> 00:03:43,910 Step two is to establish a theory of probable cause. 106 106 00:03:43,910 --> 00:03:46,090 This is the second step in our troubleshooting process, 107 107 00:03:46,090 --> 00:03:48,170 and it's used to come up with a possible solution 108 108 00:03:48,170 --> 00:03:51,110 to the problem you clearly identified back in step one. 109 109 00:03:51,110 --> 00:03:53,130 When we establish a theory of probable cause, 110 110 00:03:53,130 --> 00:03:55,830 we need to question the obvious first, for example, 111 111 00:03:55,830 --> 00:03:57,960 if the end user said they normally connect to the internet, 112 112 00:03:57,960 --> 00:04:00,870 using a wifi connection on their laptop, you may want to check 113 113 00:04:00,870 --> 00:04:02,700 that they haven't turned off the wifi card, 114 114 00:04:02,700 --> 00:04:05,360 using the toggle switch on that laptop by accident. 115 115 00:04:05,360 --> 00:04:07,320 If they did, then of course the internet is going to be down 116 116 00:04:07,320 --> 00:04:09,640 because they've turned off all wireless capability 117 117 00:04:09,640 --> 00:04:12,960 on that laptop at the physical layer of the OSI model. 118 118 00:04:12,960 --> 00:04:15,670 Also, when you're establishing your theory of probable cause 119 119 00:04:15,670 --> 00:04:18,330 you should use multiple approaches to solving the issue. 120 120 00:04:18,330 --> 00:04:20,110 This could be a top-to-bottom approach, 121 121 00:04:20,110 --> 00:04:23,300 a bottom-to-top approach or a divide and conquer approach. 122 122 00:04:23,300 --> 00:04:25,600 A top-to-bottom approach relies on troubleshooting 123 123 00:04:25,600 --> 00:04:28,580 from layer seven of the OSI model down to layer one. 124 124 00:04:28,580 --> 00:04:31,780 So we start the application layer and we work our way down. 125 125 00:04:31,780 --> 00:04:33,670 A bottom-to-top approach, instead relies 126 126 00:04:33,670 --> 00:04:35,870 on troubleshooting from layer one of the OSI model 127 127 00:04:35,870 --> 00:04:37,900 up to layer seven of the OSI model. 128 128 00:04:37,900 --> 00:04:40,590 Here we start at the physical layer by checking our cables 129 129 00:04:40,590 --> 00:04:42,500 and wireless radio-frequency connections 130 130 00:04:42,500 --> 00:04:44,750 and then we work our way up to layer two, switching, 131 131 00:04:44,750 --> 00:04:47,270 layer three, routing, and continue all the way up 132 132 00:04:47,270 --> 00:04:49,410 through four, five, six, until we get to seven 133 133 00:04:49,410 --> 00:04:51,030 at the application layer. 134 134 00:04:51,030 --> 00:04:53,330 Now the divide and conquer approach is used when we split 135 135 00:04:53,330 --> 00:04:55,800 the network or the layers of the OSI model in half 136 136 00:04:55,800 --> 00:04:57,470 and troubleshoot from there. 137 137 00:04:57,470 --> 00:04:58,960 Early in my career, I used to work 138 138 00:04:58,960 --> 00:05:00,370 as a nuclear reactor operator, 139 139 00:05:00,370 --> 00:05:02,360 and when I was troubleshooting electrical circuits, 140 140 00:05:02,360 --> 00:05:04,610 we often used this divide and conquer approach. 141 141 00:05:04,610 --> 00:05:05,960 We called it half-splitting, 142 142 00:05:05,960 --> 00:05:07,750 but it's essentially the same concept. 143 143 00:05:07,750 --> 00:05:10,400 Essentially, we would figure out what the halfway point was 144 144 00:05:10,400 --> 00:05:12,240 in the electrical circuit, and then we tested 145 145 00:05:12,240 --> 00:05:13,250 the connection there. 146 146 00:05:13,250 --> 00:05:15,120 If it worked, it meant the first half of the circuit 147 147 00:05:15,120 --> 00:05:17,550 was good and I didn't have to look at the first half anymore 148 148 00:05:17,550 --> 00:05:19,230 because everything was working properly. 149 149 00:05:19,230 --> 00:05:21,220 Then I could focus on the second half. 150 150 00:05:21,220 --> 00:05:23,840 Now I could half-split again between the halfway point 151 151 00:05:23,840 --> 00:05:25,420 and the end and I could troubleshoot again 152 152 00:05:25,420 --> 00:05:27,250 until I found where the problem was. 153 153 00:05:27,250 --> 00:05:29,410 We kept doing this over and over until we found the error 154 154 00:05:29,410 --> 00:05:31,920 and it really was a quick way to figure things out. 155 155 00:05:31,920 --> 00:05:34,150 Now, we can do the exact same thing in our networks. 156 156 00:05:34,150 --> 00:05:36,330 If I'm trying to troubleshoot the internet is down issue 157 157 00:05:36,330 --> 00:05:38,030 for this end user, I could figure out 158 158 00:05:38,030 --> 00:05:39,970 what the halfway point is between their computer 159 159 00:05:39,970 --> 00:05:41,520 and the internet, which would probably be 160 160 00:05:41,520 --> 00:05:42,890 our default gateway. 161 161 00:05:42,890 --> 00:05:45,300 I could then try to send a ping from the end-user's computer 162 162 00:05:45,300 --> 00:05:46,630 to the default gateway. 163 163 00:05:46,630 --> 00:05:48,700 If it works, that means my internal network 164 164 00:05:48,700 --> 00:05:50,530 is functioning fully, and the problem exists 165 165 00:05:50,530 --> 00:05:53,130 between my default gateway and the internet connection 166 166 00:05:53,130 --> 00:05:55,020 or the distant web server. 167 167 00:05:55,020 --> 00:05:58,120 Now, this is my halfway point and with a single ping, 168 168 00:05:58,120 --> 00:06:00,910 I already verified the entire internal network is working 169 169 00:06:00,910 --> 00:06:03,410 from the end user, all the way up to the gateway. 170 170 00:06:03,410 --> 00:06:06,010 This is my divide and conquer approach at work, 171 171 00:06:06,010 --> 00:06:09,050 also known as half-splitting if you use my terminology. 172 172 00:06:09,050 --> 00:06:11,780 Now at this point in step two, we're just coming up 173 173 00:06:11,780 --> 00:06:13,930 with a theory of what might be going wrong, 174 174 00:06:13,930 --> 00:06:16,150 such as I think the default router is down 175 175 00:06:16,150 --> 00:06:18,530 and preventing the end user from accessing the internet, 176 176 00:06:18,530 --> 00:06:20,660 but we're not trying to solve it yet, 177 177 00:06:20,660 --> 00:06:22,560 that will come in step three. 178 178 00:06:22,560 --> 00:06:25,970 So step three is test the theory to determine the cause. 179 179 00:06:25,970 --> 00:06:28,240 So now we've looked at the problem in step two 180 180 00:06:28,240 --> 00:06:30,930 and we've created our theory, we need to actually test 181 181 00:06:30,930 --> 00:06:32,560 that theory here in step three. 182 182 00:06:32,560 --> 00:06:34,820 This is where we actually begin to take some actions 183 183 00:06:34,820 --> 00:06:36,470 such as pinging the default gateway 184 184 00:06:36,470 --> 00:06:38,650 from the end user's workstation or checking 185 185 00:06:38,650 --> 00:06:40,520 network configuration on a particular router, 186 186 00:06:40,520 --> 00:06:41,860 switch or firewall. 187 187 00:06:41,860 --> 00:06:44,290 If the theory is confirmed, then we're going to determine 188 188 00:06:44,290 --> 00:06:45,780 what our next steps are going to be 189 189 00:06:45,780 --> 00:06:47,470 to solve the bigger issue. 190 190 00:06:47,470 --> 00:06:49,340 If the theory remains unconfirmed, 191 191 00:06:49,340 --> 00:06:51,250 then we're going to have to reestablish a new theory 192 192 00:06:51,250 --> 00:06:53,150 or escalate the issue to a higher tier 193 193 00:06:53,150 --> 00:06:54,610 or more senior technician, 194 194 00:06:54,610 --> 00:06:56,530 who may have additional privileges or more knowledge 195 195 00:06:56,530 --> 00:06:58,300 on how to fix this issue. 196 196 00:06:58,300 --> 00:07:00,770 Step four, we're going to establish a plan of action 197 197 00:07:00,770 --> 00:07:03,980 to resolve the problem and identify the potential effects. 198 198 00:07:03,980 --> 00:07:06,760 At this point, we now want to build out a plan of action 199 199 00:07:06,760 --> 00:07:08,310 to resolve this issue. 200 200 00:07:08,310 --> 00:07:10,430 Let's go back to our internet is down issue. 201 201 00:07:10,430 --> 00:07:12,880 We found that the default router was causing the issue, 202 202 00:07:12,880 --> 00:07:15,180 we pinged it, and in step three, we found that traffic 203 203 00:07:15,180 --> 00:07:16,840 was not getting out of the network 204 204 00:07:16,840 --> 00:07:18,880 and going past this default router. 205 205 00:07:18,880 --> 00:07:22,070 Now we can log into that modem from the ISP and verify 206 206 00:07:22,070 --> 00:07:23,650 it had a good connection to the internet, 207 207 00:07:23,650 --> 00:07:25,350 so we know the issue is definitely something 208 208 00:07:25,350 --> 00:07:26,490 to do with the router. 209 209 00:07:26,490 --> 00:07:28,830 Some reason that router is not passing traffic 210 210 00:07:28,830 --> 00:07:31,430 to the internet, but the modem and the connection is up. 211 211 00:07:31,430 --> 00:07:33,780 So we're going to look at that router, and we find out 212 212 00:07:33,780 --> 00:07:37,420 that the CPU utilization is between 90% and 100%. 213 213 00:07:37,420 --> 00:07:39,810 We now have a theory that if we reboot the router, 214 214 00:07:39,810 --> 00:07:42,660 we could clear this high CPU utilization and the traffic 215 215 00:07:42,660 --> 00:07:44,910 would again, start to flow through this router. 216 216 00:07:44,910 --> 00:07:47,700 Now, as you establish your plan of action here in step four, 217 217 00:07:47,700 --> 00:07:49,990 to reboot this router, we also need to identify 218 218 00:07:49,990 --> 00:07:51,370 the potential effects. 219 219 00:07:51,370 --> 00:07:53,230 This is an enterprise level router, 220 220 00:07:53,230 --> 00:07:56,250 so it'll take at least 10 to 15 minutes to reboot it. 221 221 00:07:56,250 --> 00:07:58,850 During that time, traffic will be unable to be routed 222 222 00:07:58,850 --> 00:08:00,900 through this router from the internal network 223 223 00:08:00,900 --> 00:08:01,810 to the internet. 224 224 00:08:01,810 --> 00:08:03,280 Now, that's not really a big deal here 225 225 00:08:03,280 --> 00:08:04,840 because the internet was down, right? 226 226 00:08:04,840 --> 00:08:07,270 And so all of our users can't access the internet anyway, 227 227 00:08:07,270 --> 00:08:09,360 because the router's not passing traffic to it. 228 228 00:08:09,360 --> 00:08:11,810 But this router may also be used to pass traffic 229 229 00:08:11,810 --> 00:08:13,930 to, and from your DMZ, your data center 230 230 00:08:13,930 --> 00:08:15,440 and other client villains. 231 231 00:08:15,440 --> 00:08:18,070 So during that reboot, the entire network, 232 232 00:08:18,070 --> 00:08:21,450 internal and external, will be essentially down. 233 233 00:08:21,450 --> 00:08:23,550 Now you need to weigh this potential effect 234 234 00:08:23,550 --> 00:08:24,850 with the action you want to take. 235 235 00:08:24,850 --> 00:08:26,950 And in most cases, you're going to have to get approval 236 236 00:08:26,950 --> 00:08:29,160 from your supervisors or the IT director 237 237 00:08:29,160 --> 00:08:31,610 to reboot this router, to solve the internet issue, 238 238 00:08:31,610 --> 00:08:33,920 even though in the next 10 to 15 minutes, 239 239 00:08:33,920 --> 00:08:35,660 you're going to cause a network wide outage 240 240 00:08:35,660 --> 00:08:37,190 by rebooting this router. 241 241 00:08:37,190 --> 00:08:39,950 All right, next step five, implement the solution 242 242 00:08:39,950 --> 00:08:41,590 or escalate as necessary. 243 243 00:08:41,590 --> 00:08:43,270 At this point, we've briefed our plan 244 244 00:08:43,270 --> 00:08:44,610 and we've gotten permission, 245 245 00:08:44,610 --> 00:08:46,650 now we're going to implement the solution. 246 246 00:08:46,650 --> 00:08:49,490 In our example, that would be rebooting the gateway router. 247 247 00:08:49,490 --> 00:08:51,590 Now, if you don't have administrative rights to do this, 248 248 00:08:51,590 --> 00:08:54,050 or the solution is beyond the scope of your abilities, 249 249 00:08:54,050 --> 00:08:56,770 you may escalate this to the next higher level technicians 250 250 00:08:56,770 --> 00:08:58,240 to deal with this problem. 251 251 00:08:58,240 --> 00:09:00,830 For example, you may be a level one network technician, 252 252 00:09:00,830 --> 00:09:02,710 and you simply don't have the proper permissions 253 253 00:09:02,710 --> 00:09:04,770 to reboot this enterprise grade router, 254 254 00:09:04,770 --> 00:09:06,800 or maybe the router was completely dead 255 255 00:09:06,800 --> 00:09:08,800 and need to be replaced, so you need a level two 256 256 00:09:08,800 --> 00:09:11,420 or level three engineer to put a new router in the rack, 257 257 00:09:11,420 --> 00:09:13,760 cable it up, load up the baseline configurations 258 258 00:09:13,760 --> 00:09:15,040 and get it working again. 259 259 00:09:15,040 --> 00:09:17,430 This would require an escalation of this problem 260 260 00:09:17,430 --> 00:09:19,090 to get it solved by these level two 261 261 00:09:19,090 --> 00:09:20,770 or level three technicians. 262 262 00:09:20,770 --> 00:09:24,370 All right, next step six, verify full system functionality 263 263 00:09:24,370 --> 00:09:27,010 and if applicable, implement preventative measures. 264 264 00:09:27,010 --> 00:09:29,730 Now, the solution has been implemented here either by you 265 265 00:09:29,730 --> 00:09:32,640 or the higher level technicians, now, we need to verify 266 266 00:09:32,640 --> 00:09:34,430 it actually solved the initial problem. 267 267 00:09:34,430 --> 00:09:37,440 So maybe we rebooted the router and then we try to connect 268 268 00:09:37,440 --> 00:09:39,660 to the website again from the end-user's computer. 269 269 00:09:39,660 --> 00:09:40,530 Did it work? 270 270 00:09:40,530 --> 00:09:42,830 If so, great, we've solved the issue. 271 271 00:09:42,830 --> 00:09:45,860 If not, we need to return to establishing a new theory 272 272 00:09:45,860 --> 00:09:47,680 and then we're going to go through the whole troubleshooting 273 273 00:09:47,680 --> 00:09:50,270 process again, to figure out how to solve it. 274 274 00:09:50,270 --> 00:09:52,630 Again, if there was some kind of cause or outage 275 275 00:09:52,630 --> 00:09:54,210 to this problem, we also want to implement 276 276 00:09:54,210 --> 00:09:57,010 preventative measures to prevent it from happening again. 277 277 00:09:57,010 --> 00:09:58,860 For example, maybe this router was having 278 278 00:09:58,860 --> 00:10:01,040 this excessively high CPU utilization 279 279 00:10:01,040 --> 00:10:02,510 because there was a routing loop. 280 280 00:10:02,510 --> 00:10:04,230 If this is the case, we need to go in 281 281 00:10:04,230 --> 00:10:06,590 and change the configurations to prevent a routing loop 282 282 00:10:06,590 --> 00:10:08,060 from occurring again in the future. 283 283 00:10:08,060 --> 00:10:09,680 Also, we may need to go back and train 284 284 00:10:09,680 --> 00:10:12,280 our network administrators who have caused that routing loop 285 285 00:10:12,280 --> 00:10:14,510 so we can show them how to avoid them in the future. 286 286 00:10:14,510 --> 00:10:16,790 This is all considered methods to prevent a recurrence 287 287 00:10:16,790 --> 00:10:18,340 of this particular issue. 288 288 00:10:18,340 --> 00:10:21,410 Finally, step seven, document findings, actions, 289 289 00:10:21,410 --> 00:10:23,150 outcomes, and lessons learned. 290 290 00:10:23,150 --> 00:10:25,840 Now that the crisis is behind us and the problem is solved, 291 291 00:10:25,840 --> 00:10:28,870 we want to document what went wrong and what we did about it 292 292 00:10:28,870 --> 00:10:30,900 and what those results were, and anything else 293 293 00:10:30,900 --> 00:10:33,140 that we learned so we can share this with others, 294 294 00:10:33,140 --> 00:10:35,190 so this problem doesn't happen again. 295 295 00:10:35,190 --> 00:10:37,760 All right, I know this was a lot of steps, 296 296 00:10:37,760 --> 00:10:39,330 but if you're using the standard network 297 297 00:10:39,330 --> 00:10:41,880 troubleshooting methodology, it will really help you 298 298 00:10:41,880 --> 00:10:44,250 to ensure you're thinking through all the possible issues, 299 299 00:10:44,250 --> 00:10:46,390 developing a theory, creating a plan of action 300 300 00:10:46,390 --> 00:10:48,400 and implementing it to successfully solve 301 301 00:10:48,400 --> 00:10:50,450 challenging issues when you're in the field. 302 302 00:10:50,450 --> 00:10:53,540 For the exam, you need to memorize these seven steps 303 303 00:10:53,540 --> 00:10:55,000 in the order that they're listed, 304 304 00:10:55,000 --> 00:10:57,970 it would be very fair for CompTIA to ask you on test day, 305 305 00:10:57,970 --> 00:11:00,010 what these seven steps are, and they can place them 306 306 00:11:00,010 --> 00:11:02,280 in a random order and ask you to drag and drop them 307 307 00:11:02,280 --> 00:11:04,730 into the right order for those seven steps. 308 308 00:11:04,730 --> 00:11:06,440 Or you can get a question that says, 309 309 00:11:06,440 --> 00:11:07,960 you're troubleshooting a network issue, 310 310 00:11:07,960 --> 00:11:10,430 and you just establish a theory of probable cause, 311 311 00:11:10,430 --> 00:11:11,570 what is your next step? 312 312 00:11:11,570 --> 00:11:12,590 And you'd have to say, 313 313 00:11:12,590 --> 00:11:14,720 test the theory to determine the cause. 314 314 00:11:14,720 --> 00:11:17,870 Now remember, these seven steps of network troubleshooting 315 315 00:11:17,870 --> 00:11:19,540 are the methodology that we're going to use 316 316 00:11:19,540 --> 00:11:21,200 and you have to memorize them. 317 317 00:11:21,200 --> 00:11:24,530 One, identify the problem, two, establish a theory 318 318 00:11:24,530 --> 00:11:26,840 of probable cause, three, test the theory 319 319 00:11:26,840 --> 00:11:29,790 to determine the cause, four, establish a plan of action 320 320 00:11:29,790 --> 00:11:32,560 to resolve the problem and identify potential effects. 321 321 00:11:32,560 --> 00:11:35,560 Five, implement the solution or escalate as necessary, 322 322 00:11:35,560 --> 00:11:38,030 six, verify full system functionality, 323 323 00:11:38,030 --> 00:11:40,620 and if applicable implement preventative measures 324 324 00:11:40,620 --> 00:11:42,890 and seven, document findings, actions, 325 325 00:11:42,890 --> 00:11:44,403 outcomes, and lessons learned. 326 326 00:11:45,704 --> 00:11:47,972 (upbeat music)