Chapter 2 - Support Cabling and Physical Installations

What is the maximum channel length for 1000BASE-T Gigabit Ethernet over Cat 5e UTP?

100 meters (328 feet) - Copper Ethernet over twisted pair, including 100BASE-TX and 1000BASE-T, is limited to 100 m for the full channel. Of that, 90 m is the permanent link and 10 m is patch cords.

Which is the minimum cable category that supports 10GBASE-T at the full 100 meters?

Cat 6A - Cat 6A supports 10GBASE-T to 100 m. Standard Cat 6 supports 10GBASE-T only up to about 55 m, and Cat 5e is not rated for 10G.

What does attenuation describe in network cabling?

The loss of signal strength as it travels along the cable - Attenuation is signal loss over distance, measured in decibels (dB). It is why cable length limits exist.

What is the main benefit of shielded twisted pair (STP) over UTP?

Greater resistance to electromagnetic interference (EMI) - The foil or braided shield blocks outside EMI from sources like motors and fluorescent lights. It costs more and must be properly grounded.

Which connector is used on Ethernet twisted-pair cable, and how many pin positions does it have?

RJ45 with 8 positions - RJ45 has 8 positions (4 pairs) and is the Ethernet standard. RJ11 is the smaller telephone connector, with 6 positions but usually only 2 to 4 wires used.

Which connector screws onto coaxial cable for cable TV (CATV) and broadband cable modems?

F-type - The F-type connector is a threaded connector used with RG-6 coax for CATV and cable modems. BNC is a twist-lock coax connector used in older networks and video.

A technician must terminate solid-core horizontal cable on the back of a patch panel. Which tool is correct?

Punch-down tool - A punch-down tool seats each conductor into the insulation displacement connector (IDC) slots. A crimper attaches RJ45 plugs to patch cable ends.

Which fiber connector uses a bayonet-style push-and-twist lock and is commonly found in older multimode installations?

ST - ST (Straight Tip) uses a twist lock. SC is push-pull, LC is a small push-pull form factor, and MPO carries multiple fibers in one connector.

What color identifies an APC (Angled Physical Contact) single-mode fiber connector?

Green - SMF cable has a yellow jacket. UPC connectors are blue and APC connectors are green. APC's angled polish reduces back reflection.

A cable tester reports that pins 3 and 6 are electrically connected to each other along the cable. What fault is this?

Short - A short means two conductors touch somewhere along the cable. An open is a break in a conductor, and a reversed or crossed pair is a wiring-order error.

A wire map tester shows no continuity on pin 4 at the far end. Which fault is this?

Open - An open fault means a conductor is broken or unterminated, so there is no continuity from end to end.

What does a Near End Crosstalk (NEXT) failure indicate?

Signal from one pair leaking into another pair, measured at the transmitting end - NEXT is crosstalk between pairs measured at the same end as the transmitter, where the signal is strongest. Poor termination or untwisting too much wire often causes it.

What cable jacket rating is required in air-handling spaces such as above drop ceilings?

Plenum (CMP) - Plenum-rated (CMP) cable uses fire-retardant jacketing (such as FEP) that produces little smoke. Riser (CMR) is for vertical runs between floors.

In structured cabling, the horizontal run from the IDF to the wall port is limited to what length?

90 meters - The permanent link is 90 m. The other 10 m of the 100 m channel is for patch cords at the work area and the patch panel.

What is the demarcation point (demarc)?

Where the provider's network ends and the customer's network begins - The demarc marks the boundary of responsibility. The provider is responsible up to it, and the customer beyond it.

A technician terminates one end of a cable using T568A and the other end using T568B. What type of cable results?

Crossover - T568A and T568B swap the green and orange pairs. Mixing them at each end creates a crossover cable. The same standard on both ends creates a straight-through cable.

Which fiber type is best for a 10 km link between two buildings?

Single-mode fiber - Single-mode fiber has a narrow core and uses laser light, supporting very long distances. Multimode has a wider core and suits shorter runs inside buildings or campuses.

What does BiDi WDM (BiDirectional Wavelength Division Multiplexing) allow?

Sending and receiving over a single fiber strand using different wavelengths - BiDi optics transmit on one wavelength and receive on another, cutting fiber needs in half.

In a hot aisle/cold aisle server room layout, which way do server intake vents face?

The cold aisle - Servers draw cool air from the cold aisle and exhaust hot air to the hot aisle. This prevents hot exhaust from mixing with intake air and improves cooling efficiency.

Which cable type connects a technician's laptop to a switch or router console port?

Rollover (console) - A rollover cable is used for out-of-band console access to network devices, not for carrying normal Ethernet traffic.

Which light source is used with single-mode fiber?

Laser - Single-mode fiber uses a laser, which allows very long distances. Multimode commonly uses LED or VCSEL sources.

Which fiber connector is a small form factor, push-pull connector that is very common on modern switches?

LC - LC is small, so more ports fit in a device. SC is larger and square, and ST uses a twist lock.

Which tool verifies cable performance, such as attenuation and crosstalk, against a standard?

Cable certifier - A certifier measures attenuation, NEXT, and more and reports pass or fail for a standard such as Cat 6A. A simple wire map tester checks only continuity and pin order.

Which room serves a single floor or area and connects horizontal cabling to the main distribution frame?

IDF - An IDF (intermediate distribution frame) is a telecommunications room that serves an area. It connects back to the MDF.