5. Network Troubleshooting Flashcards
The first step of troubleshooting; involves gathering facts and identifying what’s wrong.
Identify the Problem
Ask for logs, observe behavior, or check device status to understand the issue.
Gather Information
Speak with users to understand when and how the problem occurred.
Question Users
Look for commonalities across affected systems—errors, slowness, disconnects.
Identify Symptoms
Check if new software, updates, changes, or configurations triggered the issue.
Determine if Anything Has Changed
Attempt to recreate the issue to better understand and observe it.
Duplicate the Problem
Tackle one issue at a time rather than combining them—simplifies troubleshooting.
Approach Multiple Problems Individually
Use logic to guess the most likely root cause of the issue.
Establish a Theory of Probable Cause
Look for obvious causes before diving deep.
Question the Obvious
Start at one end of the OSI model and work your way through each layer.
Top-to-Bottom / Bottom-to-Top
Pick a midpoint in the OSI model and work toward both ends to isolate the issue.
Divide and Conquer
Run tests or replace components to validate the cause of the problem.
Test the Theory
If your theory is confirmed, create a strategy to resolve the issue.
Determine Next Steps to Resolve Problem
If your theory is wrong, either adjust your theory or escalate the issue to a higher tier.
Establish a New Theory or Escalate
Develop a fix and consider what impact it might have on the system or users.
Establish a Plan of Action
Apply the fix, or escalate if it’s outside your authority or skill set.
Implement the Solution or Escalate
Check that the fix worked, and confirm everything is running smoothly.
Verify Full System Functionality
Add configurations, alerts, or processes to prevent the issue from returning.
Implement Preventive Measures
Record everything you did, what worked, and what didn’t—used for future reference and training.
Document Findings, Actions, Outcomes, and Lessons Learned
You can’t fix what you don’t understand—this first step includes gathering all relevant details, asking questions, and confirming what’s broken.
Identify the Problem
This means pulling logs, checking error messages, examining topology maps, and reviewing system status.
Gather Information
Users can offer insight into what happened and when—crucial for timeline reconstruction.
Question Users
Recognizing patterns across systems helps isolate the issue—slow speeds, app crashes, dropped connections are all examples.
Identify Symptoms
Often the root of issues—config updates, hardware changes, or environmental factors may have triggered the problem.
Determine if Anything Has Changed
Reproducing the issue on demand helps confirm symptoms and test theories more effectively.
Duplicate the Problem
Avoid the trap of trying to fix everything at once—each problem may require a unique solution path.
Approach Multiple Problems Individually
A “working guess” based on experience or evidence—it narrows your focus before deep testing begins.
Establish a Theory of Probable Cause
Check the basics first—cables, power, mute buttons—before diving into complex analysis.
Question the Obvious
This structured method checks each OSI layer one-by-one—great for beginners or thorough testing.
Top-to-Bottom / Bottom-to-Top
Start in the middle (often the network layer) and test outward—faster for experienced techs.
Divide and Conquer
Use pings, port resets, or part replacements to verify if your theory holds water.
Test the Theory
Once you’re confident in the cause, you need a game plan to fix it—without breaking anything else.
Determine Next Steps to Resolve Problem
If tests disprove your theory, create a new hypothesis or call in a higher-tier tech.
Establish a New Theory or Escalate
Before making changes, think through what else might break—does this fix cause service downtime or impact another department?
Establish a Plan of Action
If you’ve got approval and the fix is safe, go for it—otherwise, escalate to a more senior technician.
Implement the Solution or Escalate
Just because the issue seems resolved doesn’t mean it’s fully fixed—confirm that all systems and users are working as expected.
Verify Full System Functionality
After fixing the issue, consider patching, alerts, backups, or other improvements to prevent recurrence.
Implement Preventive Measures
Write it all down—what went wrong, what fixed it, and what others should know next time. Great for team learning and future reference.
Document Findings, Actions, Outcomes, and Lessons Learned
What is the first step in the troubleshooting process?
A. Establish a theory of probable cause
B. Gather information
C. Identify the problem
D. Test the theory
C. Identify the problem
Which of the following actions is part of identifying the problem?
A. Implement the solution
B. Duplicate the issue
C. Document actions
D. Create an ACL
B. Duplicate the issue
Which method starts at one end of the OSI model and works through each layer?
A. Divide and conquer
B. Question the obvious
C. Top-to-bottom or bottom-to-top
D. Document and escalate
C. Top-to-bottom or bottom-to-top
What should you do if your original theory is proven incorrect?
A. Implement the fix anyway
B. Document your findings
C. Establish a new theory or escalate
D. Reboot all systems
C. Establish a new theory or escalate
Which step ensures the issue won’t return and that the fix didn’t break anything else?
A. Test the theory
B. Verify full system functionality
C. Duplicate the problem
D. Escalate the ticket
B. Verify full system functionality
Why is documenting your troubleshooting process important?
A. It ensures more downtime
B. It helps prevent future issues and builds institutional knowledge
C. It reduces the need for backups
D. It avoids having to test solutions
B. It helps prevent future issues and builds institutional knowledge
Which technique involves picking a midpoint in the OSI model and testing outward from there?
A. Top-down
B. Divide and conquer
C. Isolation
D. Preventive analysis
B. Divide and conquer
After confirming the theory, what comes next?
A. Document the findings
B. Implement a fix
C. Escalate the issue
D. Establish a plan of action
D. Establish a plan of action
Which troubleshooting step includes checking for patches, updates, or policy changes that might help prevent recurrence?
A. Identify the problem
B. Implement the solution
C. Document the issue
D. Implement preventive measures
D. Implement preventive measures
What is the purpose of questioning the obvious during troubleshooting?
A. To escalate more efficiently
B. To save time by checking simple fixes first
C. To delay deep analysis
D. To confirm OSI model layers
B. To save time by checking simple fixes first
Using a cable not rated for the distance or application can cause connectivity or signal issues.
Incorrect Cable
A fiber type used for long distances and high bandwidth; uses a single light path.
Single-Mode Fiber
Fiber type used for shorter distances with multiple light paths.
Multimode Fiber
Common twisted-pair copper cable types used for Ethernet.
Category 5/6/7/8
Cable that has shielding to reduce electromagnetic interference.
Shielded Twisted Pair (STP)
Twisted-pair cable that lacks shielding, more common in low-interference environments.
Unshielded Twisted Pair (UTP)
Degradation in signal strength or quality over distance.
Signal Degradation
Electrical signals bleeding into adjacent cables, causing interference.
Crosstalk
Radio-frequency or electromagnetic noise that disrupts signal integrity.
Interference
Reduction in signal strength over distance or poor-quality cable.
Attenuation
Wires are not terminated properly on connectors, leading to poor signal or no connection.
Improper Termination
Fiber or copper cables are connected in reverse, blocking communication.
TX/RX Transposed
When interface counters increase, they can indicate physical or configuration problems.
Increasing Interface Counters
Indicates data integrity issues, often caused by physical layer problems.
Cyclic Redundancy Check (CRC) Errors
Frames smaller than expected—often caused by collisions or physical damage.
Runts
Frames larger than allowed—may result from bad NICs or configuration.
Giants
Packets that are dropped due to congestion or configuration problems.
Drops
Indicates that a port is shut down due to errors or security violations.
Error Disabled
The port is manually shut down by an admin.
Administratively Down
Port is in a paused or inactive state—may be caused by protocols like STP.
Suspended
Network ports supplying power to devices like phones or APs.
Power over Ethernet (PoE)
The total power used by connected PoE devices exceeds the switch’s capacity.
Power Budget Exceeded
Using a device that doesn’t match the supported PoE type or voltage.
Incorrect PoE Standard
Pluggable modules used to convert electrical signals into optical signals (or vice versa).
Transceivers
Occurs when the module and the device or cable type don’t match.
Mismatch
Refers to the level of signal being sent or received—too weak can cause drops.
Signal Strength
Using the wrong cable type—like Cat 5 instead of Cat 6 for gigabit—can cause signal loss, slow speeds, or no connectivity.
Incorrect Cable
This fiber type is designed for long distances using a single laser light—ideal for WAN links but incompatible with multimode gear.
Single-Mode Fiber
Used over shorter distances (typically <500m), this fiber type supports multiple light paths and often uses LED-based transceivers.
Multimode Fiber
Ethernet cables vary in shielding and speed—Cat 5 tops out at 100 Mbps, while Cat 6/6a and higher are built for gigabit+.
Category 5/6/7/8
This cable has metal shielding to protect against EMI—useful in industrial or high-noise environments.
Shielded Twisted Pair (STP)
Standard Ethernet cable used in most office and residential settings—cheaper, more flexible, but less EMI-resistant.
Unshielded Twisted Pair (UTP)
When signal gets weaker as it travels across long distances or poor cables—can cause timeouts or lost packets.
Signal Degradation
When signals from one wire pair bleed into another—especially bad in unshielded or poorly installed cable.
Crosstalk
External electrical signals (e.g., from lights, motors, or radio waves) that interfere with cable performance.
Interference
Natural signal loss over distance—affects both fiber and copper. Longer runs need better cable or signal boosters.
Attenuation
Improper crimping or misaligned wires can result in flapping connections, CRC errors, or full link failure.
Improper Termination
Happens when transmit and receive lines are swapped—usually shows as no connectivity or traffic flow.
TX/RX Transposed
Interface counters are diagnostic tools—rising error counts often mean physical problems or duplex mismatches.
Increasing Interface Counters
These errors indicate data was corrupted in transit—usually due to bad cabling, interference, or failing NICs.
Cyclic Redundancy Check (CRC) Errors
Small, malformed packets (less than 64 bytes)—usually from collisions or cable damage.
Runts
Oversized packets that exceed MTU—may be caused by jumbo frames or misconfigured devices.
Giants
Packets dropped due to buffer overflow, bandwidth saturation, or hardware errors.
Drops
Switch shuts down a port after detecting errors or policy violations—often seen in port security breaches.
Error Disabled
This port state means a network admin manually shut it down via configuration.
Administratively Down
A suspended port is in a non-forwarding state—may be triggered by STP or errors.
Suspended
Supplies power to VoIP phones, access points, and cameras directly from the switch—removes need for wall adapters.
Power over Ethernet (PoE)
When too many PoE devices draw more power than the switch can provide, devices may lose power intermittently.
Power Budget Exceeded
If the switch supports PoE+ but the device needs PoE++ (or vice versa), it may not power up properly.
Incorrect PoE Standard
Small, hot-swappable modules used in fiber or high-speed copper connections—need to match port and media type.
Transceivers
Occurs when you mix incompatible transceivers or use the wrong cable type—can cause loss of link or errors.
Mismatch
Low light levels in fiber, or weak electrical signal in copper, can cause flapping, slow speeds, or dropped packets.
Signal Strength
Which of the following would most likely cause increased CRC errors on an interface?
A. Incorrect VLAN
B. Poor cable shielding
C. Spanning Tree Protocol
D. Jumbo frame support
B. Poor cable shielding
Which cable type is designed for longer distances and uses a single light path?
A. Multimode fiber
B. STP
C. UTP
D. Single-mode fiber
D. Single-mode fiber
Which issue occurs when the transmit and receive wires are reversed?
A. Runts
B. Attenuation
C. TX/RX transposed
D. CRC errors
C. TX/RX transposed
A technician notices that an interface shows a large number of “giants.” What is a likely cause?
A. Duplex mismatch
B. Oversized frames
C. Cable attenuation
D. Link flapping
B. Oversized frames
Which of the following best describes a “runt” on a network interface?
A. A dropped packet due to power issues
B. A packet smaller than the minimum frame size
C. A fiber mismatch
D. A protocol mismatch
B. A packet smaller than the minimum frame size
A network port is down and labeled “error-disabled.” What’s the likely cause?
A. The cable is unplugged
B. The port was administratively shut down
C. The port violated a policy or experienced errors
D. A switch reboot is required
C. The port violated a policy or experienced errors
What happens when a PoE switch exceeds its power budget?
A. Devices get disconnected due to overheating
B. Interfaces stop forwarding traffic
C. PoE devices may lose power or fail to start
D. VLANs stop functioning
C. PoE devices may lose power or fail to start
Which problem is most likely to cause increasing interface counters and random disconnects?
A. Incorrect VLAN
B. Improper cable termination
C. Mismatched MTU
D. Protocol mismatch
B. Improper cable termination
What is the main difference between STP and UTP cables?
A. UTP supports higher speeds
B. STP is for fiber only
C. STP has shielding to prevent interference
D. UTP is only used in industrial environments
C. STP has shielding to prevent interference
Which issue is most likely if a transceiver works with one cable type but fails with another?
A. Poor signal strength
B. Duplex mismatch
C. Transceiver mismatch
D. Incorrect VLAN tag
C. Transceiver mismatch
A protocol that prevents network loops in a Layer 2 switching environment.
Spanning Tree Protocol (STP)
Occurs when redundant links forward traffic simultaneously, causing broadcast storms and congestion.
Network Loop
The central switch selected by STP to determine path calculations.
Root Bridge
Defines how a port behaves in STP (e.g., forwarding, blocking, listening).
Port Role
STP uses these to manage transition of port states like forwarding or blocking.
Port State
A port assigned to the wrong VLAN may not receive the expected traffic.
Incorrect VLAN Assignment
Rules that allow or deny network traffic based on IP, port, or protocol.
Access Control List (ACL)
The list of known paths that a router uses to determine how to forward packets.
Routing Table
A route used when no specific path to a destination is known.
Default Route
Occurs when there are no more available IPs in a DHCP pool.
Address Pool Exhaustion
When the gateway IP address configured on a host is incorrect, it can’t reach remote networks.
Incorrect Default Gateway
Occurs when a device has an incorrect IP address, which may block network access.
Incorrect IP Address
Two devices on the same network are using the same IP address, causing intermittent or broken connectivity.
Duplicate IP Address
Incorrect network mask can cause a host to believe devices are local or remote when they aren’t, breaking routing.
Incorrect Subnet Mask
This protocol runs on switches to prevent loops by blocking redundant links unless needed as backups. Without it, broadcast storms can crash the network.
Spanning Tree Protocol (STP)
Occurs when multiple Layer 2 paths forward traffic endlessly—can flood switches and bring the network down fast.
Network Loop
The designated switch in a STP topology used as the central reference point for path decisions. If it changes unexpectedly, network behavior may change.
Root Bridge
STP assigns each port a role—such as root, designated, or blocking—to determine how traffic flows and to prevent loops.
Port Role
STP ports cycle through states (blocking, listening, learning, forwarding, disabled) that affect whether traffic is passed or paused.
Port State
If a device is placed on the wrong VLAN, it may not have access to its expected subnet, DHCP scope, or services.
Incorrect VLAN Assignment
These rules are used on routers, switches, or firewalls to permit or block traffic. A misconfigured rule can block legitimate communication.
Access Control List (ACL)
Routers rely on this table to determine where to send packets. If it’s missing entries or outdated, packets may be dropped or misrouted.
Routing Table
Used when no more specific route is found. If misconfigured or missing, devices may not reach the internet or external networks.
Default Route
When a DHCP server runs out of assignable addresses, new devices can’t connect and may receive APIPA addresses (169.254.x.x).
Address Pool Exhaustion
If this IP is incorrect, the host may be able to reach devices on the same subnet but fail to access anything outside of it.
Incorrect Default Gateway
A static or misconfigured IP can place the device on the wrong network, or outside of the DHCP scope, causing isolation or IP conflicts.
Incorrect IP Address
Two devices share the same IP—this often results in network flapping, dropped packets, or DHCP failures.
Duplicate IP Address
This defines the size of the local network. An incorrect mask can make a host misidentify which traffic is local and which needs routing.
Incorrect Subnet Mask
What is the primary purpose of Spanning Tree Protocol (STP)?
A. Assign IP addresses
B. Route internet traffic
C. Prevent Layer 2 loops
D. Encrypt VLAN traffic
C. Prevent Layer 2 loops
Which condition is most likely caused by a missing or incorrect default route?
A. Devices cannot communicate locally
B. DNS fails internally
C. External websites are unreachable
D. MAC addresses won’t resolve
C. External websites are unreachable
What happens when two hosts are configured with the same IP address?
A. One device switches to a reserved address
B. Both function normally
C. Packet collisions and intermittent connectivity
D. One device becomes a DHCP server
C. Packet collisions and intermittent connectivity
A user connects to the network but can’t reach external websites. Their IP and subnet mask are correct. What is the likely cause?
A. Duplicate IP
B. Incorrect VLAN
C. Incorrect default gateway
D. STP loop
C. Incorrect default gateway
Which of the following STP roles is responsible for forwarding traffic on the shortest path to the root bridge?
A. Blocking
B. Root port
C. Alternate port
D. Listening
B. Root port
Which of the following can cause a host to receive an APIPA address (169.254.x.x)?
A. ACL block
B. VLAN mismatch
C. Address pool exhaustion
D. Incorrect subnet mask
C. Address pool exhaustion
A router is dropping packets to a remote network. The routing table does not include a specific route. What is missing?
A. ACL
B. VLAN assignment
C. Subnet mask
D. Default route
D. Default route
An interface is in the correct VLAN but can’t access its gateway. What should you check first?
A. Duplicate IP
B. ACLs blocking the subnet
C. DHCP lease time
D. Root bridge selection
B. ACLs blocking the subnet
What problem is likely if a host can communicate locally but not with hosts on another VLAN?
A. Default gateway missing
B. VLAN assignment is incorrect
C. DNS server is down
D. IP conflict
B. VLAN assignment is incorrect
A user reports unstable network connectivity. You find their device has the same IP as a printer. What’s the issue?
A. Routing loop
B. Default route missing
C. Duplicate IP address
D. STP topology change
C. Duplicate IP address
Occurs when multiple devices or applications compete for the same limited resources.
Congestion / Contention
A weak link in the network that limits overall performance.
Bottlenecking
The maximum rate at which data can be transferred over a connection.
Bandwidth
The actual rate at which data is successfully delivered over a network.
Throughput
The delay between when data is sent and when it is received.
Latency
Data packets that fail to reach their destination.
Packet Loss
Variation in the time it takes for packets to reach their destination.
Jitter
Occurs when multiple wireless channels interfere with one another.
Channel Overlap
Weak signal strength over distance or due to obstacles.
Signal Degradation / Loss
When the wireless network does not adequately cover a physical area.
Insufficient Wireless Coverage
When clients are disconnected from a wireless network unexpectedly.
Client Disassociation Issues
Misconfigured handoffs between access points cause connection drops or slowness.
Roaming Misconfiguration
When too many users or apps try to use the same network path or resource, performance degrades — think peak hour slowness or overworked switches.
Congestion / Contention
A slow component (like a 100 Mbps switch on a gigabit network) holds back the performance of faster systems — a common issue in mixed-speed environments.
Bottlenecking
This is the theoretical maximum capacity of a network path (e.g., 1 Gbps) — not always what you actually get.
Bandwidth
The actual data transfer rate — influenced by congestion, packet loss, and hardware. If it’s much lower than the rated bandwidth, something’s wrong.
Throughput
Measured in milliseconds (ms), this delay can cause sluggish behavior in VoIP, gaming, or web apps — high latency = high frustration.
Latency
If packets never make it to the destination, it can cause audio cutouts, freezing video, or failed connections — often due to interference, poor cabling, or congestion.
Packet Loss
Inconsistent packet arrival times — major problem in real-time apps like voice or video, often due to network congestion or poor routing.
Jitter
Wireless channels (especially in 2.4 GHz) overlap — when two APs use the same or adjacent channels, interference skyrockets.
Channel Overlap
Walls, distance, and poor placement cause the wireless signal to weaken, leading to retries, dropped packets, and slow speeds.
Signal Degradation / Loss
Some areas may not have adequate Wi-Fi coverage — leads to dead zones where users lose connection entirely.
Insufficient Wireless Coverage
Clients are unexpectedly dropped from the network — could be caused by weak signal, too many clients, interference, or power saving settings.
Client Disassociation Issues
Occurs when devices don’t smoothly transition between access points — may stick to weak APs or drop entirely, often due to poor AP placement or config.
Roaming Misconfiguration
Which of the following describes a network experiencing competition for limited bandwidth?
A. Latency
B. Jitter
C. Contention
D. Roaming
C. Contention
A user reports choppy audio on VoIP calls, but latency and packet loss are within limits. What should you check next?
A. Throughput
B. Channel overlap
C. Jitter
D. Bandwidth
C. Jitter
Which wireless issue occurs when two nearby access points are using overlapping channels?
A. Signal loss
B. Roaming
C. Channel overlap
D. Jitter
C. Channel overlap
What issue might you suspect if a user’s connection is fine in one part of the office but drops in another?
A. Bottleneck
B. Insufficient wireless coverage
C. Duplicate IP
D. Looping
B. Insufficient wireless coverage
Which performance problem involves a weak link limiting the entire network’s throughput?
A. Jitter
B. Bottlenecking
C. Contention
D. Disassociation
B. Bottlenecking
A user experiences frequent disconnects from the wireless network when moving between floors. What’s the likely cause?
A. Signal degradation
B. Packet loss
C. Roaming misconfiguration
D. Channel saturation
C. Roaming misconfiguration
Which metric is most directly affected when large amounts of data are dropped and not successfully received?
A. Latency
B. Throughput
C. Bandwidth
D. ACLs
B. Throughput
What might high latency cause in user experience?
A. Instant disconnections
B. Increased download speed
C. Slow response times in applications
D. Roaming loops
C. Slow response times in applications
Which problem describes differences in arrival times of packets that affect real-time communication?
A. Packet loss
B. Latency
C. Jitter
D. Signal fade
C. Jitter
You notice clients are randomly dropping from the Wi-Fi network. What is the most likely cause?
A. MAC filtering
B. Client disassociation issues
C. Routing loop
D. DHCP scope mismatch
B. Client disassociation issues
Captures and inspects packet data flowing through a network — useful for deep traffic analysis.
Protocol Analyzer
Tests network reachability by sending ICMP Echo Requests.
ping
Displays the path that packets take to reach a destination, hop by hop.
traceroute / tracert
Resolves DNS names to IP addresses and tests name resolution.
nslookup
Captures packets from the command line for real-time analysis.
tcpdump
Performs advanced DNS queries with extended output options (Available by default on macOS and Linux, not Windows).
dig
Displays active connections, ports, and protocol usage.
netstat
Used to view and configure IP address settings on a device.
ip / ifconfig / ipconfig
Displays and modifies the local Address Resolution Protocol (ARP) cache.
arp
Scans a network to discover hosts, open ports, and services.
Nmap
Protocol that discovers directly connected Layer 2 devices.
Link Layer Discovery Protocol (LLDP)
Cisco-specific protocol that discovers neighboring Cisco devices.
Cisco Discovery Protocol (CDP)
Measures the upload/download speed and latency of an internet connection.
Speed Tester
Used to trace and identify individual cable runs in walls or patch panels.
Toner
Tests cable pinouts, continuity, and wiring faults.
Cable Tester
Hardware tool used to passively monitor or capture network traffic.
Tap
Detects nearby wireless networks, signal strength, and interference.
Wi-Fi Analyzer
A device that shines light through a fiber optic cable to identify breaks or faults.
Visual Fault Locator
Displays the MAC addresses learned on each switch port.
show mac-address-table
Displays the routing table on a router or Layer 3 switch.
show route
Displays port status, bandwidth usage, and error counters.
show interface
Shows current device configuration, including interfaces, VLANs, and IPs.
show config
Displays the ARP cache of the device.
show arp
Lists VLAN assignments and configurations.
show vlan
Shows PoE information for devices connected to switch ports.
show power
Which command is used to test DNS name resolution?
A. ping
B. traceroute
C. nslookup
D. arp
C. nslookup
A technician wants to scan a subnet for active hosts and open ports. Which tool should they use?
A. netstat
B. ping
C. Nmap
D. dig
C. Nmap
Which command shows current IP address settings on a Windows device?
A. ifconfig
B. show config
C. arp
D. ipconfig
D. ipconfig
What tool should be used to check for cabling faults like short circuits or miswires?
A. Toner
B. Tap
C. Cable Tester
D. Speed Tester
C. Cable Tester
A network engineer needs to view the MAC addresses learned on each switch port. Which command should they use?
A. show interface
B. show route
C. show vlan
D. show mac-address-table
D. show mac-address-table
Which tool can detect signal strength and channel overlap in a wireless environment?
A. Tap
B. Wi-Fi Analyzer
C. dig
D. tcpdump
B. Wi-Fi Analyzer
You’re on a macOS device and suspect a domain name is not resolving correctly. Which tool provides detailed DNS query output?
A. arp
B. traceroute
C. dig
D. tcpdump
C. dig
What is the purpose of the traceroute command?
A. Scan open ports
B. Display MAC addresses
C. Show the path to a remote host
D. Assign IP addresses
C. Show the path to a remote host
Which Cisco-specific protocol shows directly connected Cisco neighbors?
A. LLDP
B. CDP
C. ARP
D. Nmap
B. CDP
Which hardware tool is used to visually identify breaks in a fiber optic cable?
A. Visual Fault Locator
B. Cable Tester
C. Tap
D. Speed Tester
A. Visual Fault Locator
