N10-009 exam dumps: questions 301 to 329 of 329

Correct answer: A

• A. Correct.

  Correct. The scenario specifically mentions a copper Ethernet run installed near large electric motors, which are a common source of electromagnetic interference (EMI). In that type of environment, using shielded twisted pair (STP) is often preferable to unshielded twisted pair (UTP), provided it is installed and grounded properly. The symptoms also align: the link can still come up at 1 Gbps, but interference and signal degradation can cause intermittent packet loss and poor throughput under load or when nearby equipment is active. The reported high NEXT further supports a cabling quality issue that can be worsened by poor cable choice and installation in noisy environments.

• B. Incorrect.

  Incorrect. This option refers to fiber optic cabling and optics, but the scenario clearly states this is a copper Ethernet run punched down to wall jacks. Single-mode versus multimode is a valid cable-selection issue in networking, but it does not match the described installation. A candidate might choose this if focusing only on the idea of using the wrong media type, but the details rule it out.

• C. Incorrect.

  Incorrect. A TX/RX transposition issue would more likely prevent link establishment entirely unless corrected by auto-MDI/MDIX, which is common on modern Ethernet equipment. Even if auto-MDI/MDIX handled the crossover, it would not explain the strong correlation between errors and the motors running, nor would it typically produce a tester result showing high NEXT on multiple pairs. This distractor targets the common misconception that any intermittent Ethernet issue is due to pair reversal.

• D. Incorrect.

  Incorrect. The workstation is 85 meters away, which is within the standard 100-meter maximum channel length for twisted-pair Ethernet, assuming the full channel including patch cables remains within spec. Attenuation can become a problem when distances exceed standards or when cable quality is poor, but the distance given does not by itself indicate an overlength run. The interference pattern tied to the motors is a much stronger clue.

Correct answer: A

• A. Correct.

  Correct. This scenario points to interference and crosstalk in a high-EMI industrial environment. Cat 5e is not the appropriate choice for a 60-meter 10GBASE-T run, and UTP is more susceptible to external interference when routed near motors and VFDs. Cat 6a is the commonly recommended cabling standard for 10GBASE-T up to 100 meters, and using STP in electrically noisy areas can help mitigate EMI when installed and grounded/bonded properly. The mention of proper termination also matters because poor shield termination can reduce or negate the benefits of shielded cabling.

• B. Incorrect.

  Incorrect. Multimode fiber can be a valid medium for high-speed uplinks, but this option is technically flawed and does not address the stated problem correctly. Patch panels are not replaced with transceivers, and multimode fiber transceivers are not a direct fix for a copper cabling issue in the way described here. Also, the tester specifically identified alien crosstalk and EMI-related issues on the copper installation, suggesting the immediate best answer is to use the proper copper category and shielding for the environment rather than this mismatched solution.

• C. Incorrect.

  Incorrect. TX/RX transposition is a wiring issue more commonly associated with crossover/straight-through mismatches or fiber pair polarity concerns, not with 10GBASE-T performance degradation caused by EMI and alien crosstalk after the link successfully negotiates. A rollover cable is used for console connections, not Ethernet data links, so this option reflects a common but incorrect confusion between cable types.

• D. Incorrect.

  Incorrect. Although Ethernet standards define maximum channel lengths, being under 100 meters does not mean any copper category will support 10GBASE-T reliably. Cat 5e does not provide the expected 10GBASE-T support for this 60-meter industrial scenario, especially with documented alien crosstalk and EMI exposure. The misconception here is assuming distance alone determines suitability, while cable category and environmental conditions are also critical.

Correct answer: A

• A. Correct.

  Correct. A duplex mismatch is a classic cause of increasing CRC errors and runts, especially when one side is operating at full duplex and the other at half duplex. Late collisions and frame corruption can result, which often appears as CRC errors and undersized frames on switch interfaces. Because the cable has already been replaced and giants are not increasing, a Layer 1 media fault is less likely than a negotiation or configuration mismatch on the link.

• B. Incorrect.

  Incorrect. An MTU mismatch typically results in fragmentation issues at Layer 3 or oversized frames if jumbo frames are involved, which would be more consistent with increasing giant counters rather than runts. In this scenario, giants remain at 0, so oversized frames are not the primary symptom.

• C. Incorrect.

  Incorrect. Egress queue congestion usually shows up as increasing output drops or discard counters, especially during bursts of traffic. The scenario specifically states that output drops are not increasing, which makes switch congestion a poor fit for the observed interface statistics.

• D. Incorrect.

  Incorrect. A broadcast storm can cause severe congestion, high CPU utilization, and widespread packet loss, but it is not the most direct explanation for a combination of CRC errors and runts on a single server-facing interface. A storm would more commonly affect multiple ports and may increase drop counters due to congestion rather than specifically indicating frame corruption from a duplex mismatch.

Correct answer: B

• A. Incorrect.

  Incorrect. Increasing MTU affects the maximum frame size and is more relevant to giant frames or fragmentation-related issues. It does not prevent runts, which are undersized frames, and it does not address CRC errors caused by Layer 1/Layer 2 transmission problems. A common misconception is that any frame-size problem can be fixed with MTU changes, but runts and CRCs typically point elsewhere.

• B. Correct.

  Correct. A duplex mismatch is a classic real-world cause of increasing CRC errors and runts, especially when utilization is not saturated and a cable replacement did not help. For example, one side operating at full duplex and the other at half duplex can produce late collisions, frame corruption, and undersized frames. Verifying speed/duplex settings or ensuring both sides negotiate correctly is the most appropriate next step.

• C. Incorrect.

  Incorrect. Port security controls which MAC addresses are allowed on a port and can shut down or restrict a port due to policy violations. It does not correct CRC errors or runts caused by physical-layer faults or duplex mismatches. Someone might choose this option if they confuse malformed traffic with unauthorized traffic.

• D. Incorrect.

  Incorrect. Larger packet buffers are more relevant to drops caused by congestion or microbursts, where frames are discarded because the interface cannot queue them fast enough. CRC errors and runts indicate corrupted or improperly transmitted frames, not a buffering limitation. Replacing the switch before checking duplex settings would be premature.

Correct answer: B

• A. Incorrect.

  Incorrect. An err-disabled port is typically placed into a disabled state automatically by the switch after a fault or policy violation, such as port security violations, BPDU Guard, or link-flap detection, depending on platform and configuration. It is not the same as a port intentionally shut down by an administrator. A candidate might choose this if they confuse a disabled state with a manual shutdown.

• B. Correct.

  Correct. Administratively down means the interface has been disabled in the running or startup configuration, usually with the shutdown command. This is the state most directly associated with an intentional administrative action, and bringing it back up generally requires a configuration change such as no shutdown.

• C. Incorrect.

  Incorrect. Suspended does not mean the port is simply unplugged. In switching environments, suspended commonly indicates the port has been logically prevented from forwarding because of a control-plane or aggregation issue, such as an EtherChannel inconsistency or related protocol condition. Someone might choose this if they confuse logical suspension with a lack of physical carrier.

• D. Incorrect.

  Incorrect. These states do not mean the same thing. Administratively down points to a manual shutdown, err-disabled usually indicates an automatic protective disablement due to a detected problem, and suspended typically indicates a protocol or bundling-related condition. Replacing a cable would not resolve all of these states and may not resolve any of them.