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Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Network Troubleshooting Chapter 20 © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Objectives • Describe appropriate troubleshooting tools and their functions • Analyze and discuss the troubleshooting process • Tackle a variety of troubleshooting scenarios © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Overview © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Introduction to network troubleshooting © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Three parts to Chapter 20 • Troubleshooting tools • The troubleshooting process • Troubleshooting scenarios © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Troubleshooting tools © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Hardware tools – – – – – – – – – Cable tester, TDR, and OTDR Certifiers Voltage event recorder/temperature monitor Protocol analyzer Cable stripper/snips Multimeter Tone probe and tone generator Butt set Punchdown tool © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Hardware tools (cont.) – Cable testers, TDRs, and OTDRs • Devices to test for broken cables – Cable testers » Continuity problems and wire map – TDRs (time domain reflectometers) » Locates copper cable breaks – OTDRs » Locates fiber-optic cable breaks © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.1 Typical cable tester © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.2 An EXFO AXS-100 OTDR (photo courtesy of EXFO) © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Certifiers – Only use for slowdowns, not disconnects – Require a loopback on the far end – Ensure a cable can handle its rated capacity – Problems that reduce cable capacity • Crosstalk • Attenuation • Interference © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Voltage event recorder/temperature monitor – Detect power and heat problems – Cause intermittent problems – Heat problems in server rooms – Monitor power with voltage event recorder – Monitor temperature with temperature monitor © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Protocol analyzers – Monitor protocols at different layers • Application, Session, Transport, Network, Data Link – Both hardware and software tools © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • When to use a protocol analyzer – You need to see data to analyze the problem • A session fails to start • A DNS server fails to respond • Confusing information appears on the network • You suspect a rogue DHCP server exists • Excess traffic is slowing down the network © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Cable stripper or snip – Enable you to make UTP cables – Also need crimpers – Often combined in one tool © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.3 A cable stripping and crimping tool © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Multimeters – Test AC and DC voltage – Test resistance – Test continuity – A great fallback when you do not have a cable tester © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Tone probes and tone generators – Work together to identify opposite ends of unlabeled cable runs – Tone generator puts a signal (tone) on wire – Tone probe on opposite end detects the signal © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Butt sets – Hand set – Use to tap into a 66- or 110-block to test a line © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Punchdown tools – Put UTP wires into 66- and 110-blocks – Repunch a connection to make sure contacts are set © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.4 A punchdown tool in action © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Software tools – Built-in commands and utilities: o tracert/traceroute o ipconfig/ifconfig o o o o o o o ping and arping nslookup/dig hostname mtr route nbtstat netstat – Packet sniffer – Port scanners © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • tracert/traceroute – Traces all routers between two points – Use to discover where a problem lies – Problem is just beyond the last router displayed before error – Some routers block traceroute packets © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Tracing route to adsl-208-190-121-38.dsl.hstntx.swbell.net [208.190.121.38] over a maximum of 30 hops: 1 1 ms <1 ms 1 ms Router.totalhome [192.168.4.1] 2 38 ms 41 ms 70 ms adsl-208-190-12138.dsl.hstntx.swbell.net [208.190.121.38] Listing 20-1 Sample traceroute output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • ipconfig/ifconfig – Displays IP settings – ipconfig without parameters • Basic information only – ipconfig /all gives configuration details © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Ethernet adapter Main: Connection-specific DNS Suffix IPv6 Address . . . . . . . . . Temporary IPv6 Address . . . . Link-local IPv6 Address. . . . IPv4 Address . . . . . . . . . Subnet Mask . . . . . . . . . Default Gateway . . . . . . . . . . . . . . : : : : : : : 2001:470:bf88:1:fc2d:aeb2:99d2:e2b4 2001:470:bf88:1:5e4:c1ef:7b30:ddd6 fe80::fc2d:aeb2:99d2:e2b4%8 192.168.4.27 255.255.255.0 fe80::223:4ff:fe8c:b720%8 192.168.4.1 Tunnel adapter Local Area Connection* 6: Media State . . . . . . . . . . : Media disconnected Connection-specific DNS Suffix . : Listing 20-2 Sample ipconfig output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) eth0 Link encap:Ethernet HWaddr 00:02:b3:8a:7d:ae inet addr:192.168.4.19 Bcast:192.168.4.255 Mask:255.255.255.0 inet6 addr: 2001:470:bf88:1:202:b3ff:fe8a:7dae/64 Scope:Global inet6 addr: fe80::202:b3ff:fe8a:7dae/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:2206320 errors:0 dropped:0 overruns:0 frame:0 TX packets:925034 errors:0 dropped:0 overruns:0 carriers:0 collisions:0 txqueuelen:1000 RX bytes:292522698 (292.5 MB) TX bytes:132985596 (132.9 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:15414 errors:0 dropped:0 overruns:0 frame:0 TX packets:15414 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1006671 (1.0 MB) TX bytes:1006671 (1.0 MB) Listing 20-3 Sample ifconfig output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • ping – Queries by name or IP address – Uses ICMP packets – Works across routers – Problem: devices can block ICMP © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Pinging 192.168.4.19 with 32 bytes Reply from 192.168.4.19: bytes=32 Reply from 192.168.4.19: bytes=32 Reply from 192.168.4.19: bytes=32 Reply from 192.168.4.19: bytes=32 of data: time<1ms time<1ms time<1ms time<1ms TTL=64 TTL=64 TTL=64 TTL=64 Ping statistics for 192.168.4.19: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms Listing 20-4 Sample ping output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • arping – Queries by IP address – Uses ARP frames – Problem: does not cross routers – Only on UNIX and UNIX-like systems © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) ARPING 192.168.4.27 from 192.168.4.19 eth0 Unicast reply from 192.168.4.27 [00:1D:60:DD:92:C6] Unicast reply from 192.168.4.27 [00:1D:60:DD:92:C6] Unicast reply from 192.168.4.27 [00:1D:60:DD:92:C6] Unicast reply from 192.168.4.27 [00:1D:60:DD:92:C6] Listing 20-5 Sample arping output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. 0.875ms 0.897ms 0.924ms 0.977ms Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • nslookup/dig – Both diagnose DNS problems – nslookup (all operating systems) • Poor tool – considered obsolete • Without switches, provides name and IP address of default DNS server – dig – more powerful • Every OS but Windows © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) dig mx totalsem.com Listing 20-6 The dig command ; <<>> DIG 9.5.0-P2 <<>> mx totalsem.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6070 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1 ;; QUESTION SECTION: ;totalsem.com. IN MX ;; ANSWER SECTION: totalsem.com. 86400 IN MX 10 mx1c1.megamailservers.com. totalsem.com. 86400 IN MX 100 mx2c1.megamailservers.com. totalsem.com. 86400 IN MX 110 mx3c1.megamailservers.com. Listing 20-7 Output for the dig command © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • hostname – Simplest of all utilities – Returns name of host from which it runs – hostname sample output c:\> c:\>hostname Mike-win7beta © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • My Traceroute (mtr) – Dynamic (keeps running) – Equivalent to traceroute – Not available in Windows © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) My traceroute [v0.73] totaltest (0.0.0.0) Keys: Help Display mode Restart statistics Order of fields quit Packets Pings Host Loss% Snt Last Avg Best Wrst StDev 1. Router.totalhome 0.0% 5 0.8 0.8 0.7 0.9 0.1 2. adsl-208-190-121-38.dsl.hstntx.s 0.0% 4 85.7 90.7 69.5 119.2 20.8 Listing 20-9 Sample mtr output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • route – Display and edit local routing table – Type route print © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) =========================================================================== Interface List 8 ...00 1d 60 dd 92 c6 ...... Marvell 88E8056 PCI-E Ethernet Controller 1 ........................... Software Loopback Interface 1 =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.4.1 192.168.4.27 10 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 169.254.0.0 255.255.0.0 On-link 192.168.4.27 286 169.254.214.185 255.255.255.255 On-link 169.254.214.185 276 169.254.255.255 255.255.255.255 On-link 192.168.4.27 266 192.168.4.0 255.255.255.0 On-link 192.168.4.27 266 192.168.4.27 255.255.255.255 On-link 192.168.4.27 266 192.168.4.255 255.255.255.255 On-link 192.168.4.27 266 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 169.254.214.185 276 224.0.0.0 240.0.0.0 On-link 192.168.4.27 266 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 169.254.214.185 276 255.255.255.255 255.255.255.255 On-link 192.168.4.27 266 =========================================================================== Persistent Routes: None Listing 20-10 Sample route print output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • nbtstat – Windows (all versions) only – Command-line equivalent of My Network Places – Must use a switch – nbtstat –n shows local NetBIOS names © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Main: Node IpAddress: [192.168.4.27] Scope Id: [] NetBIOS Local Name Table Name Type Status --------------------------------------------MIKESPC <00> UNIQUE Registered TOTALHOME <00> GROUP Registered MIKESPC <20> UNIQUE Registered TOTALHOME <1E> GROUP Registered Listing 20-11 Sample nbtstat output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • netstat – Shows current state of running IP processes – Shows what sessions are active – Provides statistics based on ports or protocols – Type netstat to show only current sessions – Type netstat –r to show routing table (like route print) © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Active Connections Proto Local Address TCP 127.0.0.1:27015 TCP 127.0.0.1:51090 TCP 127.0.0.1:52500 TCP 192.168.4.27:54731 TCP 192.168.4.27:55080 TCP 192.168.4.27:56126 TCP 192.168.4.27:62727 TCP 192.168.4.27:63325 TCP 192.168.4.27:63968 Foreign Address MikesPC:51090 MikesPC:27015 MikesPC:52501 72-165-61-141:27039 63-246-140-18:http acd4129913:https TOTALTEST:ssh 65.54.165.136:https 209.8.115.129:http State ESTABLISHED ESTABLISHED ESTABLISHED CLOSE_WAIT CLOSE_WAIT ESTABLISHED ESTABLISHED TIME_WAIT ESTABLISHED Listing 20-12 Sample netstat output © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Packet sniffer – A.k.a. protocol analyzer or packet analyzer – Intercepts and logs network packets – Many choices – Software example: Wireshark – Dedicated hardware devices © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.5 Wireshark in action © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Port scanners – Probes remote system’s ports – Logs state of scanned ports – Good use: find unintentionally opened ports in order to close – Bad use: find open ports and use to break in – nmap runs on UNIX and Windows – Angry IP Scanner for Windows © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.6 Angry IP Scanner © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Throughput testers – Enable you to measure the data flow in a network – Which tool to use depends on what part of network you want to test – Several speed-testing Web sites available for checking an Internet connection’s throughput © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Figure 20.7 Speed test results from Speakeasy © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) The troubleshooting process © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Memorize these problem analysis steps: • Identify the problem – – – – Gather information Identify symptoms Question users Determine if anything has changed • Establish a theory of probable cause – Question the obvious © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Memorize these problem analysis steps (cont.): • Test the theory to determine cause – Once theory is confirmed, determine next steps to resolve problem – If theory is not confirmed, re-establish new theory or escalate • Create an action plan and solution identifying potential effects © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Memorize these problem analysis steps (cont.): • Implement and test the solution and escalate as necessary • Verify full system functionality and, if applicable, implement preventative measures • Document findings, actions, and outcomes © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) Troubleshooting scenarios © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Troubleshooting scenario one – “I can’t log in!” • Biggest and most complex scenario • Log in from other machines • Attempt to log in yourself and try to ping • Use ipconfig or ifconfig © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Troubleshooting scenario two – “I can’t get to this Web site!” • Have user try to reach another Web site • Try to ping the site by name and IP address • Determine whether DNS is functioning • Ping the gateway or proxy server • Ping other sites • If other sites reachable, notify problem site owner • If no sites available, notify your ISP © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Troubleshooting scenario three – “Our Web server is sluggish!” • Connect from another location • If connection is also slow, problem with server • Check server logs for changes • Run Performance Monitor and compare new logs with previously established baseline logs • If connection from other location OK, run tracert command from user’s computer to reveal slow hop © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Troubleshooting scenario four – “I can’t see anything on the network!” • Check connectivity • Ping a remote system • Ping loopback address – If error, run ipconfig /all and fix settings – If no error, check hardware » Run utility on NIC » Test cable © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • It’s time to escalate! – Broadcast storms – Switching (bridging) loops – Route problems – Routing loops – Proxy ARP © 2012 The McGraw-Hill Companies, Inc. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005) • Troubleshooting is fun! – Apply good troubleshooting methodology – Constantly increase your knowledge – Become a troubleshooting artist © 2012 The McGraw-Hill Companies, Inc. All rights reserved.