Module 4: Physical Layer

Question 1

What is the purpose of a Network Interface Card (NIC)?

Answer 1

The purpose of a Network Interface Card (NIC) is to connect a device to the network.

Question 2

Do all devices have only one Network Interface Card (NIC)?

Answer 2

No, some devices may have just one NIC, while others may have multiple NICs. For example, some devices may have both wired and wireless NICs to connect to the network.

Question 3

What is the role of the Physical Layer in a network?

Answer 3

The role of the Physical Layer is to transport bits across the network media.

Question 4

What does the Physical Layer do with a frame it receives from the Data Link Layer?

Answer 4

The Physical Layer accepts a complete frame from the Data Link Layer and encodes it as a series of signals that are transmitted to the local media.

Question 5

What organizations govern the Physical Layer Standards and what are the three functional areas addressed by these standards?

Answer 5

Answer: The Physical Layer Standards are implemented in hardware and are governed by organizations such as ISO, EIA/TIA, ITU-T, ANSI, and IEEE. These standards address three functional areas including Physical Components, Encoding, and Signaling.

Question 6

What is the purpose of Encoding in a network?

Answer 6

The purpose of Encoding in a network is to convert the stream of bits into a format recognized by the next device in the network path.

Question 7

What is Bandwidth in a network? And how is Bandwidth measured in a network?

Answer 7

Bandwidth in a network refers to the capacity at which a medium can carry data.
Bandwidth in a network is measured in bits per second, which is also known as digital bandwidth measures.

Question 8

What is Latency in a network?

Answer 8

Latency refers to the amount of time, including delays, for data to travel from one given point to another.

Question 9

What is Throughput in a network? And what is Goodput in a network?

Answer 9

Throughput measures the transfer of bits over a period of time.
Goodput is the measure of usable data transferred over a given period of time.

Question 10

What are the advantages of using Copper Cabling in networks and what are some of its limitations?

Answer 10

Copper Cabling is the most commonly used type of cabling in networks because it is inexpensive, easy to install, and has low resistance to electrical current flow. However, it has limitations in terms of attenuation, which weakens electrical signals over longer distances, and susceptibility to interference from Electromagnetic Interference (EMI), Radio Frequency Interference (RFI), and Crosstalk.

Question 11

What are the sources of interference that can affect data signals in Copper Cabling, and how does Crosstalk impact its performance?

Answer 11

The sources of interference that can affect data signals in Copper Cabling are EMI, RFI, and Crosstalk. EMI is interference caused by electromagnetic waves, and RFI is caused by radio frequency waves. Crosstalk is caused by signals from adjacent cables that are picked up by the intended cable. Crosstalk can impact the performance of Copper Cabling by causing errors and distortions in data signals.

Question 12

What is Crosstalk in Copper Cabling, and how can it be mitigated?

Answer 12

Crosstalk refers to the interference caused by electrical signals in one circuit that affects the signals in an adjacent circuit. To mitigate crosstalk in copper cabling, some kinds of copper cable use twisted pair wires, which are pairs of wires twisted together to reduce the electromagnetic interference between them.

Question 13

How can EMI and RFI be mitigated in Copper Cabling?

Answer 13

EMI (Electromagnetic Interference) and RFI (Radio Frequency Interference) can be mitigated in copper cabling by using metallic shielding and grounding. Some kinds of copper cable have metallic shielding that surrounds the wires, which helps to block out electromagnetic interference. Grounding the cable also helps to dissipate any electrical charge buildup and reduces the effects of electromagnetic interference.

Question 14

What are some advantages and disadvantages of using Shielded Twisted Pair (STP) cabling?

Answer 14

Advantages of STP cabling include better noise protection compared to UTP, while disadvantages include higher price and difficulty in installation. STP is terminated with RJ-45 connectors and is commonly used to interconnect hosts with intermediary network devices.

Question 15

What elements are standardized by TIA/EIA-568 for UTP cabling?

Answer 15

TIA/EIA-568 standardizes cable types, cable lengths, connectors, cable termination, and testing methods for UTP cabling.

Question 16

What are the standards and applications for Ethernet straight-through and Ethernet crossover cables?

Answer 16

Ethernet straight-through cable uses the T568A or T568B standard for both ends and is typically used for connecting a host device to a network device.

Ethernet crossover cable, on the other hand, uses one end of T568A and the other end of T568B and is used for connecting host-to-host, switch-to-switch, or router-to-router.

Question 17

What is the standard for Rollover cable and its application?

Answer 17

The standard for Rollover cable is Cisco Proprietary. Its application is to connect a host serial port to a router or switch console port, using an adapter.

Question 18

What are the advantages of fiber-optic cabling compared to other networking media?

Answer 18

Fiber-optic cabling transmits data over longer distances at higher bandwidth than any other networking media. It is also less susceptible to attenuation and completely immune to EMI/RFI, making it an ideal choice for certain networking scenarios. However, it is not as common as UTP due to the higher cost involved in its installation.

Question 19

What are the differences between Single-Mode Fiber and Multimode Fiber in fiber-optic cabling?

Answer 19

Single-Mode Fiber has a very small core and uses expensive lasers, making it ideal for long-distance applications. On the other hand, Multimode Fiber has a larger core and uses less expensive LEDs, which transmit at different angles, allowing for up to 10 Gbps over 550 meters.

Question 20

What are some types of Fiber-Optic Connectors?

Answer 20

Some types of Fiber-Optic Connectors are
Straight-Tip (ST) Connectors,
Lucent Connector (LC)
Simplex Connectors,
Subscriber Connector (SC) Connectors,
and Duplex Multimode LC Connectors.

Question 21

What is Wireless Media

Answer 21

Wireless Media carries electromagnetic signals representing binary digits using radio or microwave frequencies. This provides the greatest mobility option

Question 22

Can you list some limitations of wireless media in computer networking?

Answer 22

• Coverage area can be significantly impacted by the physical characteristics of the deployment location
• Susceptibility to interference and disruption by common devices
• Security concerns due to the lack of physical access control
• Operation in half-duplex, resulting in reduced bandwidth for each user when many users access the WLAN simultaneously.

Question 23

What is the purpose of WiMAX technology?

Answer 23

WiMAX technology is designed to provide broadband wireless access with a point-to-multipoint topology.

Question 24

What is the difference between Bluetooth and Zigbee standards?

Answer 24

Bluetooth is a wireless personal area network (WPAN) standard, while Zigbee is designed for low-data-rate, low-power applications with a focus on home automation and industrial control.

Question 25

What devices are required for a wireless LAN (WLAN)?

Answer 25

A wireless LAN (WLAN) requires two main devices: a wireless access point (AP) and wireless NIC adaptors. The AP acts as a central hub, connecting the wireless devices to the wired network, while the NIC adaptors are installed on each wireless device, allowing it to communicate with the AP and access the network.