Section 5: Media and Connectors

Question 1

What is the primary purpose of twisting the wires in a twisted-pair cable?

Answer 1

To cancel out electromagnetic interference (EMI) and reduce crosstalk from adjacent cables.

Question 2

What is the key structural difference between UTP and STP cables?

Answer 2

STP (Shielded Twisted-Pair) includes an additional layer of metallic shielding to protect against EMI, while UTP (Unshielded Twisted-Pair) does not.

Question 3

In what type of environment is it critical to use STP cabling instead of UTP?

Answer 3

In environments with a high degree of electromagnetic interference (EMI), such as factories with heavy machinery or hospitals.

Question 4

What are the main trade-offs when choosing STP over UTP?

Answer 4

STP offers better EMI protection but is more expensive, bulkier, and more difficult to install than UTP.

Question 5

What is the maximum data rate of a CAT5e cable at 100 meters?

Answer 5

1 Gbps (1000 Mbps).

Question 6

What is the maximum data rate of a CAT6a cable at 100 meters?

Answer 6

10 Gbps.

Question 7

What is the primary difference in capability between a CAT6 and CAT6a cable?

Answer 7

A CAT6a cable can maintain a 10 Gbps speed up to the full 100 meters, whereas a CAT6 cable can only maintain 10 Gbps up to 55 meters.

Question 8

For what specific environment was the CAT8 standard designed?

Answer 8

For short-distance, high-speed connections within data centers, such as between servers and switches in the same rack.

Question 9

Which twisted-pair category supports 1 Gbps at 100 meters?

Answer 9

CAT5e and CAT6.

Question 10

Which twisted-pair category supports 40 Gbps but only up to 30 meters?

Answer 10

CAT8.

Question 11

What is the modern standard for residential coaxial cable, used for cable internet and TV?

Answer 11

RG-6.

Question 12

What is the primary limitation of an RG-59 cable compared to an RG-6 cable?

Answer 12

RG-59 has a thinner inner conductor, resulting in lower bandwidth and frequency capabilities, making it unsuitable for modern high-definition or internet applications.

Question 13

What is a Direct Attach Copper (DAC) cable primarily used for?

Answer 13

For short, high-speed connections between switches, routers, and servers within a data center rack.

Question 14

What is the key structural difference between a standard coaxial cable and a twinaxial cable?

Answer 14

A twinaxial cable has two inner conductors running in parallel, whereas a standard coaxial cable has only one.

Question 15

What are the two standard pinouts for terminating Ethernet cables? Which is more common?

Answer 15

T568A and T568B. The T568B standard is more commonly used in new installations in the United States.

Question 16

What is the pinout for T568B?

Answer 16

From pin 1 to 8: Orange/White, Orange, Green/White, Blue, Blue/White, Green, Brown/White, Brown.

Question 17

What cable type is created when both ends are wired to the T568B standard?

Answer 17

A Straight-Through cable (also known as a patch cable).

Question 18

When is a crossover cable required instead of a straight-through cable?

Answer 18

When connecting two similar devices directly, such as a switch to a switch or a PC to a PC, assuming the devices do not support Auto-MDIX.

Question 19

What modern switch feature often makes crossover cables unnecessary?

Answer 19

Auto-MDIX (Medium Dependent Interface Crossover), which automatically detects the required cable type and adjusts the port electronically.

Question 20

A cable with a T568A pinout on one end and T568B on the other is what type of cable?

Answer 20

A Crossover cable.

Question 21

What are the three main advantages of fiber optic cabling over copper cabling?

Answer 21

1. Higher bandwidth, 2. Longer transmission distances, and 3. Complete immunity to electromagnetic interference (EMI).

Question 22

What is the physical difference between single-mode fiber (SMF) and multi-mode fiber (MMF)?

Answer 22

SMF has a much smaller core diameter (8-10 microns) than MMF (50-100 microns).

Question 23

What is the typical jacket color for single-mode fiber? For multi-mode fiber?

Answer 23

Single-mode fiber is typically yellow. Multi-mode fiber is typically orange or aqua.

Question 24

Which type of fiber optic cable is used for very long-distance communication, such as between cities?

Answer 24

Single-Mode Fiber (SMF), because its small core minimizes light dispersion, allowing the signal to travel for many miles.

Question 25

A fiber optic cable with an aqua-colored jacket is most likely what type?

Answer 25

Multi-Mode Fiber (MMF).

Question 26

What connector is known as the 'stick and twist' and uses a bayonet locking mechanism?

Answer 26

ST (Straight Tip) connector.

Question 27

What connector is known as the 'stick and click,' has a square shape, and a push-pull mechanism?

Answer 27

SC (Subscriber Connector).

Question 28

What fiber connector is favored in high-density data centers due to its small form factor?

Answer 28

LC (Lucent/Little Connector).

Question 29

What is the main purpose of polishing the end-face of a fiber connector?

Answer 29

To minimize signal loss and back reflection, which is light that reflects back to the signal's source and degrades performance.

Question 30

What is the key difference between a UPC and an APC polish, and what is the visual indicator for an APC connector?

Answer 30

An APC polish has an 8-degree angle on the end-face to greatly reduce back reflection, while a UPC polish is dome-shaped. APC connectors are visually identified by their green color.

Question 31

A green fiber optic connector indicates what type of polish?

Answer 31

APC (Angled Physical Contact).

Question 32

What is the primary function of a network transceiver like an SFP or QSFP module?

Answer 32

To convert signals between different media types in a modular, hot-pluggable form factor, most commonly converting a switch's electrical signal to a fiber optic light signal.

Question 33

What is the main difference between SFP+ and QSFP+ transceivers in terms of speed?

Answer 33

QSFP+ (Quad Small Form-factor Pluggable Plus) supports higher aggregate speeds (up to 40 Gbps) than SFP+ (up to 16 Gbps), typically by using four channels instead of one.

Question 34

What does it mean for a transceiver to be 'hot-pluggable'?

Answer 34

It can be inserted into or removed from a network device (like a switch or router) while the device is running, without needing to power it down.

Question 35

When would you use a standalone media converter instead of a transceiver module?

Answer 35

When you need to convert between media types but the network device (like an older switch or a computer) does not have modular slots to accept a transceiver.

Question 36

What is a 'plenum' space in a building?

Answer 36

A space used for circulating air for heating, ventilation, and air conditioning (HVAC) systems, such as the area above a drop ceiling or below a raised floor.

Question 37

What is the key difference in the material properties of a plenum-rated cable versus a non-plenum cable?

Answer 37

A plenum-rated cable has a fire-retardant plastic jacket that produces minimal smoke, while a non-plenum cable uses less expensive materials that are not as fire-resistant.

Question 38

Why is it a safety hazard to use non-plenum cable in a plenum space?

Answer 38

If it catches fire, a non-plenum cable will produce more toxic smoke and fumes, which can be quickly circulated throughout the building by the HVAC system.

Question 39

What organizations define the standards requiring the use of plenum-rated cables?

Answer 39

The National Fire Protection Association (NFPA) and the National Electrical Code (NEC).