Endpoints and Media Types practice questions

The Blue pair (Pins 4 and 5)

Why it fails: The blue pair is located on pins 4 and 5 in both the T568A and T568B standards. These pins are traditionally used for telephony and are not part of the primary data transmission pairs for 10/100 Mbps Ethernet, so they remain unchanged in a standard crossover cable.

The Brown pair (Pins 7 and 8)

Why it fails: The brown pair, located on pins 7 and 8, is not swapped when creating a standard crossover cable between T568A and T568B. Like the blue pair, these wires are not used for data in 10/100Base-T Ethernet, though they are used for all four pairs in Gigabit Ethernet transmissions.

The Red pair (Pins 9 and 10)

Why it fails: Standard RJ-45 Ethernet connectors only utilize eight pins, numbered 1 through 8. There is no 'red pair' or pins 9 and 10 in the TIA/EIA 568A or 568B specifications. This option describes a non-existent configuration that does not apply to standard twisted-pair network media types.

An incorrect IP address on the laptop's NIC

Why it fails: An IP address is a Layer 3 configuration and does not affect the physical link light. Even if the laptop has no IP address or an incorrect one, the NIC and the switch port should still establish a physical link as long as the cabling and hardware are functional.

The switch port has been administratively disabled

Why it fails: When a switch port is 'shutdown' by an administrator, the port is powered off and will not attempt to establish a link with any connected device. This results in no link light at both the switch and the endpoint, regardless of the quality of the cabling used.

The laptop is using a DHCP-assigned address

Why it fails: DHCP is a protocol used for dynamic address assignment at Layer 7 and Layer 3. Like static IP addressing, it has no impact on the physical layer's ability to establish a link. Link lights are purely a function of the hardware sensing an active electrical or optical carrier.

A dipole antenna

Why it fails: A dipole antenna is a type of omnidirectional antenna, but it typically has a lower gain and a more limited coverage pattern compared to a dedicated high-gain omnidirectional antenna. In a large warehouse with metal obstructions, a simple dipole may not provide sufficient range or penetration, making it less effective than a higher-gain omnidirectional option.

A Yagi antenna

Why it fails: A Yagi antenna is a directional antenna that focuses the signal in one direction, which is useful for point-to-point links or covering a specific narrow area. In a large open warehouse where coverage is needed across a broad area, a directional antenna would leave many areas without adequate signal, making it unsuitable for this scenario.

A parabolic dish antenna

Why it fails: A parabolic dish antenna is highly directional and used for long-distance point-to-point links, such as building-to-building connections. It concentrates the signal into a very narrow beam, which would not provide the wide coverage needed in a warehouse with metal shelving and multiple client devices scattered throughout the space.

10GBASE-T SFP+ with Cat 6a UTP

Why it fails: 10GBASE-T over Cat 6a UTP supports distances up to 100 meters, which falls short of the required 150 meters. While Cat 6a can handle 10 Gbps, the distance limitation makes it unsuitable. The engineer would need to use fiber or consider a different copper solution, but standard 10GBASE-T does not meet the distance requirement.

10GBASE-LR SFP+ with single-mode fiber

Why it fails: 10GBASE-LR is designed for long-range transmissions up to 10 kilometers over single-mode fiber. While it would easily cover 150 meters, it is more expensive and unnecessary for such a short distance. Using single-mode fiber and LR optics for a 150-meter run is not cost-effective and is typically reserved for campus or metro links. Therefore, it is not the most appropriate choice for this scenario.

10GBASE-SR SFP+ with multimode fiber

Why it fails: 10GBASE-SR uses multimode fiber but is limited to a maximum distance of 400 meters on OM4 fiber, which exceeds 150 meters. However, it may be overkill and more expensive than necessary. The distance is within range, but the question asks for the best fit; 10GBASE-SR is typically used for shorter distances up to 300-400 meters, but 10GBASE-LR is more suitable for longer runs. Still, 10GBASE-SR would technically work, but it is not the optimal choice for 150 meters when considering cost and common practice.

Coaxial cable

Why it fails: Coaxial cable is wrong because the switch and router have RJ-45 10/100/1000BASE-T ports, which require twisted-pair copper cabling. Coaxial cable is used for older Ethernet standards like 10BASE5 or cable Internet connections, not for modern Ethernet ports. It would not physically fit the RJ-45 interfaces and would not support the required speeds.

Rollover cable

Why it fails: A rollover cable is incorrect because it is used for console connections to manage network devices, not for Ethernet data links. It reverses all eight pins, which would not allow the switch and router to communicate over Ethernet. Rollover cables are typically flat light-blue cables with RJ-45 connectors used with a terminal emulator to access the CLI.

Crossover cable

Why it fails: A crossover cable is wrong because it swaps the transmit and receive pairs, which is required when connecting similar devices such as switch-to-switch or router-to-router. Here, the devices are different types (switch and router), so their internal pinouts already expect a straight-through cable. Using a crossover cable would cause the transmit pair of one device to connect to the transmit pair of the other, preventing a link.

Cat 8

Why it fails: Cat 8 supports 25GBASE-T and 40GBASE-T but only up to 30 meters. It is designed for short data center runs, not 80 meters. Although it can handle 10GBASE-T, the distance limitation makes it unsuitable for this deployment. Therefore, it is not an appropriate choice.

Cat 5e

Why it fails: Cat 5e supports only 1 Gbps up to 100 meters and does not meet the 10GBASE-T requirement. It may handle 2.5GBASE-T or 5GBASE-T at limited distances, but not 10 Gbps. Thus, it is insufficient for the specified 10GBASE-T connection over 80 meters.

Cat 7

Why it fails: Cat 7 is a shielded cable that supports 10GBASE-T up to 100 meters, but it uses GG45 or TERA connectors, not standard RJ-45. While it can handle the distance and EMI, its non-standard connector may not be compatible with typical switch and server ports. Therefore, it is not the best choice for this scenario.

IEEE 802.3bt

Why it fails: IEEE 802.3bt is the latest PoE standard supporting up to 90 watts for high-power devices like laptops and LED lighting. It is backward compatible, but it is not the standard specifically required for typical IP phones. Using it would work but is unnecessary and may not be supported on all switches.

IEEE 802.3at

Why it fails: IEEE 802.3at, also known as PoE+, provides up to 30 watts per port and is designed for devices requiring more power, such as dual-radio wireless access points or PTZ cameras. While it can power an IP phone, it is not the minimum standard necessary and may be overkill for a standard phone.

IEEE 802.1X

Why it fails: IEEE 802.1X is a port-based network access control standard used for authentication, not power delivery. It ensures only authorized devices can access the network but does not provide electrical power over the Ethernet cable. This is unrelated to powering an IP phone.

Pin 1

Why it fails: Pin 1 carries the white/orange conductor of pair 2 in the T568B scheme, and it is used for transmit data on a straight-through cable, but the question asks for the transmit pin associated with pair 2 at the connector, and the specific pin numbering is what matters here. Pin 1 does carry transmit, but it is not the pin the technician must verify for pair 2's transmit function in this termination scenario.

Pin 3

Why it fails: Pin 3 carries the white/green conductor of pair 3, which in T568B is the receive data (RX+) pin on a straight-through cable. The technician terminating a T568B outlet would find pin 3 associated with the green pair, not the orange pair, so it is not the transmit pin for pair 2 in this scenario.

Pin 6

Why it fails: Pin 6 carries the solid green conductor of pair 3 and serves as the receive data (RX-) pin in T568B. Because pair 3 is used for receive rather than transmit on a standard endpoint connection, pin 6 does not correspond to the transmit signal of pair 2, making it incorrect for this termination task.

Omnidirectional antenna

Why it fails: An omnidirectional antenna radiates equally in all directions horizontally, which can cause signal reflections and multipath in a warehouse with metal shelving. This may lead to unpredictable coverage and dead spots. While it supports both bands, it does not provide the most predictable pattern in this environment, so it is not the best choice.

Yagi antenna

Why it fails: A Yagi antenna is a directional antenna, but it is typically narrowband and may not support both 2.4 GHz and 5 GHz simultaneously. It is often used for long-distance point-to-point links. While directional, its frequency limitations make it less suitable for an AP that must serve both bands in a warehouse.

Dipole antenna

Why it fails: A dipole antenna is a type of omnidirectional antenna, so it shares the same drawbacks in a reflective environment. It radiates in a doughnut-shaped pattern and may cause multipath issues with metal shelving. Therefore, it does not offer the predictable coverage needed for this warehouse deployment.

The access point is using a 2.4 GHz channel instead of 5 GHz

Why it fails: While 2.4 GHz generally offers lower throughput and more interference than 5 GHz, the scenario emphasizes that degradation appears only when many users are active. Band choice alone does not explain load-dependent behavior as directly as airtime contention does. A strong signal on 2.4 GHz can still deliver acceptable speed when the channel is not congested.

Incorrect SSID configuration on the client

Why it fails: If the client had the wrong SSID, it would not associate with the access point at all or would connect to a different network. The scenario states the client is connected and has strong signal, so SSID misconfiguration is inconsistent with the symptoms. It would cause association failure, not degraded throughput under load.

A duplex mismatch on the wired uplink

Why it fails: A duplex mismatch on the wired uplink would affect all clients on that access point consistently, not only when many users are active. It would also typically cause collisions or errors visible in interface statistics. The symptom described is load-dependent wireless contention, so a wired duplex issue is not the most likely cause.

Omnidirectional antenna

Why it fails: An omnidirectional antenna is wrong because it radiates signal in all directions horizontally, which is inefficient in a warehouse with metal shelving that causes reflections and multipath. It would waste signal in unwanted directions and may not provide sufficient coverage down long aisles. It is better suited for open office spaces where coverage is needed in all directions.

Dipole antenna

Why it fails: A dipole antenna is wrong because it is an omnidirectional antenna typically used for general coverage. In a warehouse with metal obstructions, its all-around pattern would cause signal to bounce off metal shelves, leading to multipath interference and poor performance. It does not provide the directional focus needed to cover aisles effectively.

Parabolic antenna

Why it fails: A parabolic antenna is incorrect because it is highly directional and used for long-distance point-to-point links, such as building-to-building bridges. It has a very narrow beamwidth, which is not suitable for covering a warehouse area with multiple aisles and racks. It would require precise alignment and would not provide the broad coverage needed inside a building.

Straight-through cable

Why it fails: A straight-through cable connects pin 1 to pin 1 and pin 2 to pin 2 between ends, which is appropriate when connecting a workstation (MDI) to a switch (MDI-X). Because the legacy router is also functioning as an MDI device and the switch port is MDI-X, a straight-through cable would leave transmit pins facing transmit pins, preventing a valid link in this scenario.

Console cable with DB-9 adapter

Why it fails: A console cable with a DB-9 adapter is used to access the command-line interface of a Cisco device through a serial port. It is not an Ethernet media type and cannot carry network data traffic between the switch and router, so it does not address the physical link requirement described in the scenario.

Rolled cable

Why it fails: A rolled cable reverses all eight pins from end to end and is used for console connections to a Cisco device's management port, not for Ethernet data links. It does not provide the transmit-to-receive pair swap needed between an MDI router and an MDI-X switch port, so it would not bring up the network link in this scenario.

Cat 3

Why it fails: Cat 3 is an older voice-grade cable rated for 10 Mbps Ethernet and telephony. It lacks the bandwidth and pair quality for any gigabit or 10-gigabit Ethernet standard. It is completely unsuitable for a 10GBASE-T backbone and would not even support 1000BASE-T reliably.

Cat 5e

Why it fails: Cat 5e is rated for 1000BASE-T and cannot reliably support 10GBASE-T. Its electrical characteristics, particularly crosstalk and insertion loss at higher frequencies, fall short of what 10 Gigabit Ethernet requires. Using Cat 5e for a 10GBASE-T link would result in link failure or severe performance degradation.

Cat 7

Why it fails: Cat 7 is a shielded cable standard that supports high frequencies, but it uses GG45 or TERA connectors rather than standard RJ-45 and is not recognized by TIA/EIA as a mainstream Ethernet category. For a typical 10GBASE-T deployment with RJ-45 ports, Cat 6a is the recognized choice, making Cat 7 inappropriate here.

Cat 6

Why it fails: Cat 6 cable can support 10GBASE-T but only up to 55 meters, not the full 100 meters. In a data center rack, distances are typically short, but the question asks for appropriate cable types for 10GBASE-T deployment. Cat 6 is limited and may not be reliable for all runs, especially if distances approach or exceed 55 meters. Cat 6a or Cat 7 are the recommended choices.

Cat 5e

Why it fails: Cat 5e is rated for 1 Gigabit Ethernet (1000BASE-T) and can sometimes support 2.5GBASE-T or 5GBASE-T over limited distances, but it does not meet the requirements for 10GBASE-T. Using Cat 5e for 10GBASE-T would result in unreliable performance or link failure. It is not suitable for this deployment.

Cat 3

Why it fails: Cat 3 cable is an older standard supporting only up to 10 Mbps Ethernet. It is completely inadequate for 10GBASE-T, which requires much higher bandwidth and stricter cable specifications. Cat 3 is obsolete for modern data center deployments and would not function in this scenario.

Single-mode fiber (OS2)

Why it fails: Single-mode fiber OS2 is incorrect because while it supports 10 Gigabit Ethernet over distances up to 10 kilometers, it is more expensive and requires different optics (10GBASE-LR) than multimode. For a 300-meter run, multimode OM3 is more cost-effective and equally capable. Using single-mode would be overkill and require more costly transceivers and fusion splicing, increasing deployment costs unnecessarily.

Multimode fiber (OM2)

Why it fails: OM2 multimode fiber is wrong because it supports 10 Gigabit Ethernet only up to 82 meters, which is insufficient for the 300-meter distance. OM2 has a modal bandwidth of 500 MHz·km, better than OM1 but still not enough for 10G at 300 meters. Using OM2 would lead to link failure or high error rates due to signal degradation over the longer distance.

Multimode fiber (OM1)

Why it fails: OM1 multimode fiber is incorrect because it has a core size of 62.5 microns and a modal bandwidth of 200 MHz·km. For 10 Gigabit Ethernet, OM1 supports only up to 33 meters, far short of the required 300 meters. Using OM1 would result in excessive signal attenuation and dispersion, preventing reliable 10G operation over that distance. It is outdated for high-speed, long-distance applications.

Category 6 UTP cabling

Why it fails: Standard Category 6 copper cables are strictly limited to a maximum distance of 100 meters for data transmission. Attempting to run copper for 500 meters results in excessive signal attenuation and data loss, making it unsuitable for connecting buildings or large warehouse sections without active repeaters or switches.

Shielded Twisted Pair (STP) cabling

Why it fails: Shielded Twisted Pair provides better protection against interference but is still bound by the 100-meter distance limitation defined in TIA/EIA standards. While it might mitigate noise from warehouse equipment, it cannot overcome the physical attenuation of electrical signals over the half-kilometer distance required for this specific network scenario.

Category 5e crossover cabling

Why it fails: Category 5e cables are legacy copper standards that support Gigabit speeds but are limited to the same 100-meter distance constraint as other twisted-pair media. Using a crossover pinout would not solve the distance problem, and modern Auto-MDIX features on switches have largely made specialized crossover cables unnecessary.

RJ-45

Why it fails: The RJ-45 connector is the standard interface used for copper Ethernet connections, such as UTP or STP cables. It uses eight pins to make electrical contact and is physically incompatible with fiber optic ports, which require optical alignment rather than electrical contact to transmit data successfully.

BNC

Why it fails: BNC connectors are typically used with coaxial cables for older thinnet networks or for professional video equipment. They use a bayonet-style twist-lock mechanism and are not used for modern fiber optic networking, as they are designed for electrical signals carried over a copper conductor and shield.

F-type

Why it fails: F-type connectors are threaded connectors primarily used with coaxial cables for cable television and broadband internet modems. They are not designed for data networking endpoints like switches or fiber patch panels and do not possess the precision alignment required for successful fiber optic light transmission.

The physical cable is disconnected.

Why it fails: If the physical cable were disconnected, the interface status would show as 'down/down' or 'administratively down'. The 'up' status for the first part of the output indicates that the hardware detects a carrier signal from the connected endpoint, confirming that the physical electrical connection is intact.

The switch port has been administratively disabled.

Why it fails: If the administrator had manually disabled the port using the shutdown command, the output would clearly state 'administratively down, line protocol is down'. Since the interface is 'up', it means the port is enabled and attempting to communicate with the device on the other end.

The MAC address on the server is incorrect.

Why it fails: MAC addresses are burned into the hardware and do not cause a line protocol to go down simply by being 'incorrect'. The switch learns MAC addresses from incoming frames; while a security policy like Port Security might disable a port, it would typically result in an err-disabled state.

Upgrade the cabling to Category 6a UTP.

Why it fails: While Category 6a supports higher bandwidth and has tighter twists, it is still unshielded (UTP) and remains susceptible to external electromagnetic interference from high-voltage lines. Upgrading the category without adding shielding or changing the media type to fiber will likely not resolve the intermittent connectivity drops.

Install a wireless bridge between endpoints.

Why it fails: Wireless signals are also highly susceptible to interference in industrial environments, particularly from large motors and electrical equipment. Introducing a wireless bridge might introduce more latency and instability rather than solving the fundamental problem of physical layer interference that is currently affecting the wired infrastructure.

Configure the switch ports for half-duplex.

Why it fails: Switching to half-duplex reduces the overall efficiency of the link and increases collisions, which would degrade performance further rather than fixing the interference issue. Duplex settings are logical configurations and cannot protect the physical medium from the electrical noise generated by nearby high-voltage power lines.

900 MHz

Why it fails: While 900 MHz is used for some long-range proprietary wireless systems and older cordless phones, it is not a standard frequency for common Wi-Fi endpoints like laptops and smartphones. It lacks the bandwidth required for modern high-speed data transmission and is not part of the 802.11 standards.

60 GHz

Why it fails: The 60 GHz band is used by the 802.11ad standard for extremely high-speed, very short-range communication, but it is not commonly supported by standard office endpoints. Its inability to penetrate walls makes it unsuitable for general-purpose office Wi-Fi, where mobility and coverage are essential requirements.

10 GHz

Why it fails: The 10 GHz range is generally reserved for specialized radar or satellite communications and is not used by consumer or enterprise Wi-Fi endpoints. Using this frequency for standard networking would require specialized hardware and licenses, as it falls outside the unlicensed ISM bands used by 802.11 devices.