Physical Layer

Question 1

Types of Data transmission

Answer 1

• Electrical
• Light
• Air (radiation)

Question 2

Measure of Bandwidth

Answer 2

GigaBITS per second, MegaBITS per second (NOT bytes)

Question 3

What is Latency

Answer 3

Amount of time including delays

Question 4

Theoretical Bandwidth

Answer 4

Throughput

Question 5

Actual Bandwidth

Answer 5

Goodput

Question 6

Only sending or receiving at a time

Answer 6

Hal-Duplex

Question 7

Sending and receiving at the same time

Answer 7

Full-Duplex

Question 8

Best Practice for Switches with auto-negotiation Half and Full-Duplex?

Answer 8

Turn it manually to Full-Duplex

Question 9

Host to Network Devices (Straight-through or Crossover)

Answer 9

Straight-through

Question 10

Host-to-Host, Switch-to-Switch, Router-to-Router (Straight-through or Crossover)

Answer 10

Crossover

Question 11

Serial port to Console Port (Cisco Proprietary)

Answer 11

Rollover

Question 12

Feature of automatically detect Straight-Through or Crossover Cable

Answer 12

Auto-MDIX

Question 13

How many cores does a copper cable have for receiving and sending?

Answer 13

• 2 for receiving
• 2 for sending

2 Adern für Empfang und 2 Adern für Versand.

Question 14

Why are copper cables twisted? are they all twisted the same?

Answer 14

• to reduce crosstalk.
• No, differently times twisted.

Getwistete Adern stören sich weniger gegenseitig.

Question 15

Two types of twisted pair cable

Answer 15

• Shielded Twisted Pair (STP)
• Unshielded Twisted Pair (UTP)

CAT7 unterstützt bis zu 10 Gbps.

Question 16

What are the types of interference that can occur in copper cables?

Answer 16

• Electromagnetic interference (EMI)
• Radio frequency interference (RFI)
• Crosstalk (electric or magnetic fields of another wire)

Diese Störungen können das Signal beeinträchtigen.

Question 17

For what are Koaxialkabel used today? and is it Full-Duplex?

Answer 17

• to connect antennas
• Koaxial is Half-Duplex

Koaxialkabel arbeiten im Half Duplex Modus.

Question 18

What are the advantages of Fiber-Optic?

Answer 18

• no EMI
• longer ranges
• faster

Fiber-Optic-Kabel verwenden Lichtimpulse zur Datenübertragung.

Question 19

For which range is Multimode used, for which Single-Mode Fiber?

Answer 19

• Single-Mode Fiber: long distance (over 500m)
• Multimode Fiber: short distance (under 500m)

Multimode Fiber bietet mehr Bandbreite.

Question 20

Is Wireless LAN Half-Duplex or Full-Duplex?

Answer 20

Half-Duplex

Wireless LAN kann nur in eine Richtung gleichzeitig kommunizieren.

Question 21

What should be kept in mind when planning a wireless setup?

Answer 21

• Thick concrete walls
• Microwaves
• Radio signal

Diese können die Signalstärke und -qualität beeinflussen.

Question 22

Which frequencies are typically used by Wireless LAN?

Answer 22

• 2.4 GHz
• 5 GHz

Verschiedene Frequenzen helfen, Störungen zu minimieren.

Question 23

What is Wi-Fi?

Answer 23

Standard for wireless network (IEEE 802.11)

Wi-Fi ist eine spezifische Implementierung von Wireless Technologien.

Question 24

What are wireless standards?

Answer 24

• Wi-Fi
• Bluetooth
• WiMAX
• Zigbee

Diese Standards definieren verschiedene drahtlose Kommunikationsprotokolle.

Question 25

Difference between Single-Mode and Multimode Fiber?

Answer 25

* Single-Mode: small core, one light impulse * Multi-Mode: multiple light impulses with different angle

Question 26

In the end, is actually 2.4 GHz the actual frequency?

Answer 26

No, for better differentiation slightly different like 2.41, 2.45 etc.

Question 27

A copper cable should not be longer than

Answer 27

100m

Question 28

Main criteria for choosing network media

Answer 28

* maximum distance * environment it should be installed * amount of data and what speed * cost of media and installation