Troubleshooting Tools Flashcards by Kelvin Castillo

Snip/cutter - Is used to simply cut a piece of cable off of a larger spool or run of cable

Cutting cable off a larger spool (twisted pair, coax, or bigger bundles).

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What does a cable stripper do?

Removes the outer jacket of a cable so the inner wires can be prepared for connectors.

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What is the purpose of a cable crimper?

Attaches connectors (RJ45, RJ11, RG6, RG59) onto cable ends.

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What does a cable tester check?

Continuity and proper pin-outs (straight-through or crossover) for each wire inside the cable.

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What does a wire map tool detect?

Open pairs, shorts, split pairs, reverse pairs, crossed pairs.

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What does a cable certifier tell you that a cable tester does NOT?

Cable category (Cat5/6/7/8), length, delay, resistance, and throughput.

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What is a multimeter used for in networking?

Measures voltage, resistance, and continuity in copper cables and power outlets.

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What does a punch down tool do?

Terminates cables on 66/110 blocks by pushing wires into the block and trimming excess.

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What is a tone generator used for?

Sends a tone through a cable so the probe can locate the cable on the other end (finding unknown or unlabeled wires).

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What does a loopback adapter do?

Loops transmit pins back to receive pins to test NIC functionality and network connectivity.

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What does a TDR locate?

The distance to a break or fault in copper cabling.

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What does an OTDR do?

Locates breaks/faults in fiber optic cables by measuring light reflections.

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What does a fiber light meter measure?

The amount of light loss through a fiber (in dB) using LED (multimode) or laser (single-mode).

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What is a fusion splicer used for?

Permanently joins two fiber optic cables together by melting the ends.

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What does a network TAP do?

Creates a copy of traffic for monitoring/security tools while letting the live traffic continue.

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What does a spectrum analyzer measure?

Signal strength (amplitude) across different frequencies—used for electrical or RF analysis.

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What is an open pair?

One or more wires not connected at one end (a break).

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What is a short in cabling?

Two wires touch or connect when they shouldn’t.

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What is a split pair?

One wire from a pair is mixed with a wire from a different pair—rare but causes big issues.

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What is a reverse pair?

The two wires of a pair are swapped on the opposite ends (pin reversed).

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When you’re dealing with the physical layer of your network, especially if you’re dealing with copper or fiber cabling, you’re going to be using a lot of different tools:

Snips & cutter

Cable strippers

Cable crimpers

Cable testers

Wire maps

Cable certifiers

Multimeters

Punchdown tools

Tone generators

Loopback adapters

Time-domain reflectometers

Optical time-domain reflectometers

Fiber light meters

Fusion splicers

TAps

Spectrum analyzers

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For the exam, it’s important for you to understand which tool you might use to troubleshoot which type of cable and which type of issue

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Used to conduct wireless surveys to ensure proper coverage and to prevent non-desired overlap between wireless access point coverage zones and channels

Wireless Analyzer

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Used to capture and analyze signals and data traffic over a communication channel

Protocol Analyzer

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Used to capture packets running over a network connection in real time and save for later analysis

Packet Capturing Tool

Verifies the real-world throughput from a client device all the way out to the Internet and back

Bandwidth Speed Test

Determines which ports are open on a network

Port Scanner

Performs monitoring, troubleshooting and in-depth inspection, interpretation, and synthesis of traffic flow data

NetFlow Analyzer

Used to search for an detect IP addresses and other information related to devices on the network

IP Scanner

Displays all of the current TCP/IP network configuration values and refreshes DHCP and DNS settings for a Windows client/server

IP Configuration (ipconfig)

Command line tool used in Unix, Linux, and OS X systems to display IP addresses information

Interface Configuration (ifconfig)

ifconfig - Status of the currently active interfaces ifconfig en0 - single interface ifconfig -a - All available interfaces

Assigns an address to a network interface or configures network interface parameters on a Unix, Linux, or X systems

What does ipconfig do?

Displays current TCP/IP configuration on Windows and lets you refresh DHCP/DNS settings.

What info does plain ipconfig show?

IPv4, IPv6 link-local, subnet mask, default gateway.

What does a 169.254.x.x IP mean?

DHCP failed → Windows assigned an APIPA address.

What does ipconfig /release do?

Drops the existing DHCP IP configuration (removes IP, mask, gateway).

What does ipconfig /renew do?

Requests a new IP from DHCP using the DORA process.

What does ipconfig /all show?

Full TCP/IP details: MAC address, DNS server, DHCP server, lease times, adapter description.

What does ifconfig -a do?

Shows all interfaces, including inactive ones.

What does ifconfig down and ifconfig up do?

Disables or enables a network interface.

What extra details does ifconfig show by default?

IPv6, IPv4, MAC address (ether), netmask (hex), broadcast address, interface status.

What is the ip command used for?

Modern tool to configure interfaces, IP addresses, routing, and more on Linux/Unix/macOS.

What does ip a show?

Interface address information (like ifconfig’s standard output).

How do you assign a static IP using ip?

ip a add /mask dev

How do you remove a static IP using ip?

ip a del /mask dev

What ip command changes a MAC address?

ip link set dev address

How do you enable promiscuous mode on an interface?

ip link set dev promisc on

Why is the ip command preferred over ifconfig?

ip has more features, is modern, actively supported, and replaces ifconfig entirely.

What ip commands turn a NIC off and on?

Off: ip link set down On: ip link set up

Checks the connectivity between two devices and most often used for network troubleshooting

ping

Displays the path between device and its destination, showing the source and destination IP address for each hop along the way

traceroute/tracert

Any router or firewall that is in the path of the transmission from the client to the destination

Hop

Traceroute = “Show me every stop between me and the website.” It shows you: Every router/hop your data passes through Where the connection might be slow or failing

Ping Troubleshooting steps:

Step 1: Ping a website ping google.com -- Works > Internet + DNS OK -- Fails Go to Step 2 Step 2: Ping Google's IP ping 8.8.8.8 -- Works > DNS problem -- Fails > Go to Step 3 Step 3: Ping your router (default gateway) -- Example: 192.168.1.1 -- Works > Problem between router/internet --Fails > Go to Step 4 Step 4: Ping your own IP -- Example: ping 192.168.1.23 -- Works > Cable or switch problem -- Fails > Go to Step 5 Step 5: Ping localhost -- ping 127.0.0.1 -- Works > Network card OK > IP config issue -- Fails > Network card driver broken > reinstall

Used to query the DNS to provide the mapping between domain names and IP addresses or other DNS records

Name Server Lookup (nslookup)

Displays just the name and the requested information for a host or domain name

Non-interactive Mode

Allows a user to query name servers for information about various hosts and domains

Interactive Mode

Used t conduct queries against DNS name servers, and is only available for Linux, Unix, and OS X by default

dig

Displays the hostname portion of the full computer name for a given system

hostname

Used to display and modify entries in the arp cache on a given system

Address Resolution Protocol (arp)

Help set up device entries before they connect to a Layer 3 switch or to prevent timeouts

Static arp Entries

Clears the entire arp cache by not specifying what to delete

arp -d

Used to display inf for IP-based connections on a client

Network Statistics (netstat)

LISTENING = waiting ESTABLISHED = talking TIME_WAIT = just hung up CLOSE_WAIT = other hung up, you still holding

netstat -s

statistics info will help determine the health of the network connection

A command line tool that display TCP IP and other packets that are being transmitted or received over a network | tcpdump and wireshark are often used together to capture and analyze packets

tcpdump

Used to discover hosts and services on a computer network by sending packets and analyzing the responses it received

Network Mapper (nmap)

Refers to any router, switch, or firewall

Network Platform

Cisco - show interface, show config, show route, Juniper - show interfaces, show configuration, show route Sidewinder - cf interface, cf config, cf route status

Displays the statistics for a network interface on the device

show interface

Displays the current system configuration

show config

Displays the current state of the routing table on the device

show route

The "show mac address-table" command displays the MAC address table on a Cisco switch

The "show arp" command is used to display the ARP table, which is the Address Resolution Protocol table, inside that device

The "show vlan" command is used to display VLAN settings on a given switch

The "show power" command is used to display and configure power settings

What does show mac address-table do?

Shows which MAC addresses are on which switch ports. Helps you see what device is plugged into what port. Shows: VLAN/BID, MAC address,type (usually dynamic).Port (like Fa0/18)

What does show arp do?

Shows IP → MAC address mappings. Check if devices are mapped correctly. Detect ARP poisoning or weird mappings. Protocol (Internet / IPv4) IP address Age MAC (hardware address) Type (ARPA = IPv4) Interface (like Eth0/0)

What does show vlan do?

Shows all VLANs and which ports belong to them. Shows: VLAN number VLAN name Status (active/not) Ports in each VLAN Simple idea: VLAN = “group of ports separated from others.” This command lists those groups.

What does show power do?

Shows PoE (Power over Ethernet) info per port. Why use it? See which ports are giving power. Troubleshoot PoE devices like IP phones. Shows: Port (interface) Admin mode (auto/on/off) Operational state (on/off) Power used Connected device PoE class Max power available

An open standard protocol that allows devices to advertise themselves and discover the information about other devices, which promotes interoperability across different vendors

Link Layer Discovery Protocol (LLDP)

A Cisco-proprietary protocol that offers similar functionalities to LLDP, but is tailored for use in Cisco environments, including routing and switching devices made by Cisco

Cisco Discovery Protocol (CDP)

When you're dealing with the Cisco Discovery Protocol its going to facilitate the collection of detailed device information, including things like:

Model numbers, IP addresses, Connected interfaces, power consumption

Both LLDP and CDP are instrumental in maintaining an accurate and comprehensive inventory of network devices | network security, network performance, network reliability

Another valuable use of the info provided by LLDP and CDP is to conduct performance optimization

Network segmentation, load balancing, quality of service settigns

These protocols also require careful configuration and management | it's crucial to implement these protocols with a mindful approach to security

LLDP - Multi-vendor environment CDP - Cisco-centric network

You are a network technician troubleshooting connectivity issues in a large office building with multiple WiFi networks. To identify potential interference and optimize signal strength, which tool would be most effective for investigating WiFi signals?

WiFi analyzer - Is specifically designed to scan and analyze WiFi networks, providing detailed info on signal strength, channel utilization, and potential interference.

You are a network administrator troubleshooting DNS resolution issues for your organization's website. You suspect there might be a problem with the DNS records. You want to be able to use a command that allows an in-dept query and that allows you control over the environment. Which of the following commands should you use?

nslookup - Allows you to query the DNS and map the IP address with the DNS records. It has an interactive mode that allows for more in-depth queries and more control over the environment.

You're a network engineer investigating network performance issues in a large office environment. Users complain about delays when accessing resources on the local network. After reviewing the network infrastructure, you suspect there might be issues with address resolution. Which command would you use to inspect the network device's cache for IP and MAC address mappings?

show arp - revels the ARP cache, essential for diagnosing address resolution issues and verifying IP-MAC mappings.

In a bustling office environment, Kirsty, a network technician, is tasked with identifying connectivity issues in a cluttered server room. Wires snake through the room, shelves are stacked with equipment, and desks are filled with paperwork. Amidst this chaos, the technician needs a tool to pinpoint the exact connections causing trouble. What tool should the technician use to efficiently identify connectivity issues in the cluttered server room?

Toner

Leon, a network security analyst, is investigating suspicious network activity in a large corporate office. It has a combination of both wireless and wired access. They need to monitor traffic within the building to plan for additional office space. Leon wants to determine resource usage and optimize performance. The network spans multiple floors, with various departments interconnected. Which tool should Leon use to examine the traffic?

NetFlow Analyzer - Used to monitor, troubleshoot, and anlyze traffic flow data. It is helpful in planning so that areas will have adequate resources and also for optimizing performance by determining the type of traffic that are using resources

Troubleshooting Tools Flashcards

(92 cards)