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Networking Fundamentals > Week 3 - The Physical Layer > Flashcards

Week 3 - The Physical Layer Flashcards

1
Q

What is Throughput?

A

The Measure of bits transferred over the media per unit of time.

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2
Q

What is crosstalk?

A

Interference caused by a signal flowing through adjacent wiring in cabling, thus creating EMI.

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3
Q

What technique minimises crosstalk in UTP?

A

Wires are twisted into pairs.

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4
Q

What connector does a network interface card use?

A

RJ-45

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5
Q

State an advantage of fibre optic over copper cabling.

A

Fiber can carry a signal much further than copper.

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6
Q

In fiber, why are two strands used in a single cable?

A
  • To achieve full duplex transmission (the media can both send and receive data simultaneously) - Remember, light can only travel in one direction!
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7
Q

A network administrator is designing the layout of a new wireless network. Which areas of concern should be accounted for during the construction of the network?

A
  • Security
  • Coverage
  • Interference
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8
Q

Which layer of the OSI model is responsible for specifying the encapsulation method used to pass data to differing types of media.

A

The Data Link layer! It is the layer above the physical layer. As different media requires data to be encapsulated in different ways, the Data Link prepares the data for transmission across the particular media, the Physical layer then converts this to bits and handles the timing and synchronisation of the signalling.

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9
Q

What are two services performed by the Data Link layer of the OSI model?

A
  1. )It accepts layer three packets and encapsulates them into frames.
  2. ) It provides media access control and error detection.
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10
Q

What are two reasons for using frame encoding techniques (How groups of bits represent certain functions\values)?

A
  1. The physical layer adds its own bits to distinguish where each frame starts and ends.
  2. The physical layer also has to distinguish which bits are data bits and which bits are control bits trough the identification of signal patterns and code groups.
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11
Q

A Network Administrator notices that newly installed Ethernet cabling is carrying corrupt and distorted data signals. The new cabling was installed in the ceiling close to fluorescent lights ad electrical equipment. Which two factors may interfere with copper cabling and result in signal distortion and corruption?

A
  • Electromagnetic Interference (EFI)

- Radio Frequency Interference (RFI)

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12
Q

What is contained in the trailer of the data link frame?

A
  • It contains data relating to error correction.
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13
Q

As Data travels on the media as a stream of 1s and 0s, how does a receiving note identify the beginning and end of a frame?

A
  • The transmitting node inserts a series of bits to distinguish the start and end of each frame.
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14
Q

What is the FCS section of a frame?

A

The FCS portion is the Frame Check Sequence. It is used to verify that the frame has been received without any error or loss.

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15
Q

What is the CRC?

A

The CRC (Cyclic redundancy check) takes the FCS (Frame Check Sequence) found in the Ethernet frame and performs a polynomial division on it at each ends, if the check doesn’t match, the frame has been corrupted.

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16
Q

What method is used to manage Contention-based access on a wireless network?

A

CSMA/CA (Carrier Sense Multiple Access - Collision Avoidance)

17
Q

How does CSMA - CA Operate?

A
  • When a wireless device wishes to transmit data, it first checks the media to see if its busy then announces its intention to use the media to other devices (this obviously increases traffic)
  • If the media is busy, the device attempts again after a random period of time.
18
Q

A Network Administrator wishes to implement a network with both wired and wireless connectivity. Under which situation would a wireless connection be recommended?

A

The end user required mobility when connecting to the network.

19
Q

What is the purpose of the OSI physical layer?

A

Transmitting bits across the local media.

20
Q

What is a function of the Logical Link Control (LLC) sublayer?

A

To take packets from the Internet layer and Encapsulate then into frames.

21
Q

What Makes fibre preferable to copper cabling for interconnecting buildings?

A
  • Can carry signal over a greater distance.
  • Immune to RFI and EMI.
  • Greater Bandwidth Potential.
22
Q

The term ………………. indicates the capacity of a medium to carry data and is typically measured in kilobits per sound or megabits per second.

A

Throughput

23
Q

What Acronym is used to reference the Data Link sublayer that identifies the network layer Protocol encapsulated in the frame?

A

Logical Link Control (LLC)

24
Q
  1. ) When is a straight through cable used?

2. ) What standards are used on each end of the cable?

A
  1. ) Host to Networking Device (E.g Switch, Hub, Router)
  2. ) Both Ends EITHER T568A or T568B (Each Cable is full duplex, but uses two sets of pairs to both send and receive. A switch transmits and receives on opposite pairs to the host device, so no signal collision occurs)
25
Q
  1. ) When is a crossover cable used?

2. ) What standards are used on each end of the cable?

A
  1. ) Either:
    - Two hosts (A computer to computer)
    - Two Intermediate Devices (Switch to Switch, Router To Router)

2.) T568A On one end, T568B on the other.
(Two devices uses two pairs of wiring to send and receive data. If the devices are the same, a straight through cable would result in the devices transmitting and receiving across the same cabling which results in signal collision! As such, one device must have its transmission switched to the opposite pair through an opposite connector)

26
Q

State the differences between single mode and multi mode fibre optic.

A
  • Single = Smaller Core.
  • Single = Less Dispersion.
  • Single = Suitable For Long Range Backbone Networks, Light In Multimode tends to disperse after some distance.
  • Single = Uses lasers, Multi uses LED’s.
  • Single = Often spans campus backbones over thousands of meters, multi is used within LAN’s or up to a couple of hundred meters within a campus network.
  • Single = Single strand of fiber, much more costly to buy, install and maintain.
27
Q
  1. ) State the max range of Copper Media
  2. ) State the max throughput of Copper Media
  3. ) State the levels of immunity to RDI and EMI of Copper Media
  4. ) State the levels of immunity to Electrical Hazards of Copper Media
  5. ) State the cost of Copper Media
  6. ) State the installation skill required to install Copper Media
  7. ) State the level of safety precautions needed to be taken when installing Copper Media
A
  1. ) 10Gbps
  2. ) 100m
  3. ) Low
  4. ) Low
  5. ) Lowest
  6. ) Lowest
  7. ) Lowest
28
Q
  1. ) State the max range of Fibre Optic
  2. ) State the max throughput of Fibre Optic
  3. ) State the levels of immunity to RDI and EMI of Fibre Optic
  4. ) State the levels of immunity to Electrical Hazards of Fibre Optic
  5. ) State the cost of Fibre Optic
  6. ) State the installation skill required to install Fibre Optic
  7. ) State the level of safety precautions needed to be taken when installing Fibre Optic
A
  1. ) 100Gbps
  2. ) 100,000 meters
  3. ) Completely immune
  4. ) Completely immune
  5. ) Highest
  6. ) Highest
  7. ) Highest
29
Q

For the 802.11a standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 54Mbps
  2. )5Ghz
  3. ) None
30
Q

For the 802.11b standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 11Mbps
  2. ) 2.4Ghz
  3. ) None
31
Q

For the 802.11g standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 54Mbps
  2. ) 2.4Ghz
  3. ) 802.11b
32
Q

For the 802.11n standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 600Mbps
  2. ) 2.4 Or 5Ghz
  3. ) 802.11b/g
33
Q

For the 802.11ac standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 1.3Gh
  2. ) 5Ghz
  3. ) 802.12n/g/b
34
Q

For the 802.11ad standard, state:

  1. ) It’s max speed.
  2. ) It’s frequency.
  3. ) It’s backward compatibility (if any)
A
  1. ) 7Gbps
  2. )2.4Ghz, 5Ghz Or 60Ghz
  3. )802.11ac/n/g/b
35
Q

Explain the contention based media access for wired Ethernet connections.

A

CSMA/CD (Carrier Sense Multiple Access/ Collision Detection) works by anticipating collisions.

  1. ) First, a device checks the media to see if it is clear.
  2. ) If this device is interrupted mid-transmission whilst waiting for packets, the device warns other devices the media is occupied. Each device then tries again at a random interval.

Networking Fundamentals (6 decks)

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