Troubleshooting Tools

Kyle Broussard and Alexandra Mikolai

Hardware Tools

Broken Cables• Broken cables cause permanent disconnections, not

slowdowns• Types of broken cables

1. Open circuit2. Short3. Wire map problem4. Crosstalk5. Noise6. Impedance mismatch

Cable Testers, TDRs, and OTDRs

• Cable testers tell you if there’s a continuity problem or if a wire map is incorrect• TDR and OTDR tell where the break in the

cable is• TDR = time domain Reflectometers• OTDR = optical time domain reflectometers

Cable Certifiers• Certifiers test cable to ensure it can handle

its rated capacity• Should use when there is a slowdown or to

eliminate cabling as the problem

Voltage Event Recorder/ Temperature Monitor

• Heat and power problems can manifest as intermittent problems• Use to monitor server rooms over time to

detect and record issues with electricity and heat

Protocol Analyzers• Monitor the different protocols running at

different layers on the network• Helps to determine slowdowns on a

network by giving an idea of excess or unexpected traffic

Cable Strippers, Snips, and Crimpers

• Used to make UTP cables

Multimeters• Test voltage, resistance and continuity• Only tool to read amount of voltage on a

line• Used also for continuity testing if cable

tester is unavailable

Tone Probes/Generators• Used together to help locate a particular

cable

Butt Sets• Used to test whether a particular phone

line is working or not

Punchdown Tools• Put UTP wires into 66- and 110-blocks. • Only used diagnostically to repunch a

connection

Software Tools

Built-In Software

The traceroute Command

• Trace all routers between two points• Diagnose where the problem lies when unable to reach remote

system• Many routers block ICMP packets

The mtr Command

The ipconfig and ifconfig Commands

The ping and arping Commands

• Ping• Uses ICMP packets to query by IP or name• Works across routers

• Arping• Use if ping doesn’t work• Uses ARP frames instead of ICMP packets• ARP frames do not cross routers, can only be used within broadcast domains• UNIX based systems

The nslookup/dig Commands

The hostname Command

The route Command

The nbtstat Command

• Windows only program• Should always be ran with a switch• Most useful switch is –n which shows the local NetBIOS names

• Useful way to see what systems are on your network

The netstat Command

Third-Party Software

Packet Sniffer

• Also called protocol analyzers• Intercepts and logs packets• Wireshark

Port Scanners

• Probes ports on other systems• Used to look for unintentionally opened ports• Used by hackers • Nmap

Throughput Testers

• Measures data flow in a network• Speedtest.net