Physical Layer

Question 1

Properties of Copper Cabling

Answer 1

• Inexpensive, easy to install
• low resistance to electrical current.
• Issues with Electromagnetic Interference (EMI), Radio Frequency Interference (RFI) and Crosstalk.

Question 2

How to deal with EMI and RFI

Answer 2

metallic shielding and grounding

Question 3

How to deal with crosstalk

Answer 3

twisting opposing circuit pair wires together

Question 4

Properties of Fiber-Optic cabling

Answer 4

• transmit data over longer distances
• high bandwidth
• immune to EMI & RFI
• made of flexible extremely thin strand of very pure glass
• uses laser or LED to encode bits as pulses of light

Question 5

Best case usage of Fibre-optic cabling

Answer 5

Enterprise Networks - backbone cabling applications and interconnecting infrastructure devices
Fiber-to-the-Home (FTTH) - always-on broadband services to home and small business
Long-Haul Networks - connect countries and cities
Submarine cable Networks - harsh undersea environments

Question 6

Single-mode fiber

Answer 6

Very small core, expensive lasers, LED transmit in straight line, long-distance applications

Question 7

Multimode fiber

Answer 7

larger core, uses less expensive LEDs, LEDs transmit at different angles, up to Gbps over 550 meters

Question 8

Wireless media

Answer 8

Uses radio or microwave frequencies.
Coverage is impacted by physical characteristics of deployment location.
Interference - can be disrupted by many common devices
Security - requires no physical access
WLANs operate in half-duplex, can result in reduced bandwidth

Question 9

Types of Copper Cabling

Answer 9

Unshielded Twisted-Pair
Shielded Twisted-Pair
Coaxial Cable

Question 10

Cable types (UTP)

Answer 10

Ethernet Straight-Through - Host to Network Device
Ethernet Crossover - interconnect similar devices
Rollover - Cisco Proprietary