CCNA Cabling Questions

This question tests knowledge of Ethernet cabling standards and speed limitations. Cat5e and Cat6 cables support Gigabit Ethernet up to 100 meters, but using an older Cat5 cable (which only supports 100 Mbps) will cap the speed. The correct answer identifies the cable category as the likely culprit.

This question tests understanding that Cat5e supports Gigabit Ethernet, but poor termination or cable damage can cause issues. The correct answer is that the terminations may have poor contact or are not fully inserted, as 1000Base-T uses all four pairs and is less tolerant of faults than 100Base-TX.

Cables run through ceilings without proper support can be damaged by ceiling tiles or other equipment. The intermittent nature suggests a physical issue like a kink or pinch. Always ensure cables are secured and protected in plenum spaces.

Shielded twisted pair (STP) cables have a metal shield that reduces EMI. In industrial environments with heavy machinery, STP is preferred over unshielded cables. Fiber optic would also work but is more expensive and harder to terminate.

This question tests knowledge of Ethernet distance limits and solutions. The correct answer is to use a PoE extender or a switch at the midpoint, as 120 meters exceeds the 100-meter limit for Ethernet, and PoE may also have voltage drop issues.

A cable that was working but now fails often indicates physical damage. The length is within spec, so it's not a distance issue. The most common cause is a break or cut in the cable, possibly from recent activity.

This question tests the understanding of Ethernet distance limitations and when to use fiber optic cabling. Copper Ethernet (Cat6) is limited to 100 meters, so a 150-meter run requires fiber optic cable, which can support Gigabit speeds over longer distances. The correct answer identifies fiber as the solution.

Cat5e cables are rated for Gigabit Ethernet up to 100 meters, so a 75-meter run should be fine. The issue is likely that the cable is not Cat5e or higher; Cat5 cables only support 100 Mbps. Always verify the cable category when troubleshooting speed issues.

This question tests knowledge of Ethernet cabling standards and performance limitations. The correct answer is that the cable is likely Cat5e or lower, as Cat5e is only certified for Gigabit up to 100 meters, but older Cat5 may only support 100 Mbps. The scenario highlights the importance of using proper cabling for desired speeds.

This question tests understanding of crossover cables and modern networking. The correct answer is that most modern switches have Auto-MDIX, so a crossover cable may still work, but if the switch is older, it could cause connectivity issues. However, the symptom of local access but no internet suggests a different problem, so the crossover cable is likely not the issue.

Cat6 supports 1 Gbps up to 100 meters, so 80 meters is fine. The question tests knowledge of distance limits for different categories. Cat6 also supports 10 Gbps up to 55 meters, but for 1 Gbps, the limit is 100 meters.

This question tests understanding of cable termination quality and crosstalk. The correct answer is that the untwisting of pairs at the termination point is too long, which can cause NEXT failures.

This question tests understanding of physical cable damage due to improper installation. Sharp bends can exceed the cable's bend radius, causing internal wire damage or shorts. The correct answer identifies this as the root cause.

This question tests knowledge of 10GbE connectivity options. The correct answer is multimode fiber with LC connectors, as SFP+ ports typically use fiber or DAC cables, and multimode fiber with LC is common for short-range 10GbE in data centers.

This question tests understanding of shielded cabling and its application in high-EMI environments. STP (shielded twisted pair) reduces electromagnetic interference, making it suitable for runs near machinery. The correct answer emphasizes the shielding benefit.

This question tests understanding of Ethernet pinout and fault isolation. The correct answer is that the cable is likely damaged or broken on the pairs used for 1000Base-T (all four pairs), but 100Base-TX only uses pairs 1-2 and 3-6. The symptom indicates a break in the cable affecting the secondary pairs.

This question tests best practices for structured cabling, specifically labeling and documentation. Proper labeling at both ends of each cable run simplifies future troubleshooting and maintenance. The correct answer emphasizes this fundamental practice.

Fiber optic cable can transmit data over long distances without signal loss, making it ideal for inter-building connections. Copper Ethernet is limited to 100 meters. Wireless could work but may be less reliable than fiber.

This question tests advanced knowledge of cable certification and speed negotiation. A cable certifier tests for compliance, but if the cable passes, the issue may be with the patch cables or connectors, which can degrade performance even if the permanent link is good. The correct answer identifies the patch cables as the likely weak point.

This question tests understanding of electromagnetic interference (EMI) and how it affects network cabling. Unshielded twisted pair (UTP) cable is susceptible to EMI from sources like fluorescent lights, causing intermittent connectivity. The correct answer highlights the lack of shielding as the key factor.

VoIP phones typically use Ethernet for data and power (PoE). Cat6a supports higher frequencies and is backward compatible, making it ideal for future-proofing. Cat5e is also sufficient but Cat6a offers better performance.

This question tests knowledge of Power over Ethernet (PoE) as a cabling-related concept. The correct answer is to use a PoE switch or injector, which sends power over the Ethernet cable, eliminating the need for a separate power adapter.

Plenum-rated cables have a special jacket that does not emit toxic fumes when burned, required by fire codes for air handling spaces. PVC cables are not allowed because they produce hazardous smoke. This is a safety and code compliance issue.

This question tests the use of basic cable testing tools in a troubleshooting scenario. A cable tester can quickly identify faults like breaks, shorts, or miswiring. The correct answer prioritizes the most direct tool for the symptom.

If only one pair of wires is faulty, Gigabit Ethernet (which uses all four pairs) will fall back to 100 Mbps (which uses only two pairs). This is a common issue with damaged cables. A faulty pair may not cause a complete link loss but will reduce speed.

This question tests knowledge of cabling standards for high-speed Ethernet. Cat6a is rated for 10 Gbps up to 100 meters, making it suitable for this distance. The correct answer distinguishes Cat6a from Cat6, which has shorter 10 Gbps support.

This question tests understanding of cable termination and wiring standards. A faulty termination at the wall jack or patch panel is a common cause of intermittent or no connectivity. The correct answer focuses on the physical connection at the new location.

This question tests basic troubleshooting for physical cable damage. The correct answer is that the cable is likely damaged from being stepped on, causing intermittent connectivity.

This question tests understanding of Ethernet wiring errors. The correct answer is that a swap of pairs 1-2 and 3-6 creates a crossover cable, which may still work with Auto-MDIX, but if not, it can cause a 'No Link' or 'Unidentified Network' error.

Cat6a supports 10 Gbps up to 100 meters, making it suitable for this distance. Cat6 supports 10 Gbps only up to 55 meters, so it would also work but with less margin. Cat5e is limited to 1 Gbps, and Cat3 is for voice.