Computer Networks Components

Questions and Answers

What is the primary function of a Network Interface Card (NIC) in a computer network?

To connect the computer to the network and establish a LAN.

What is the primary function of a router in a network?

To connect LANs and WANs and make decisions on routing data packets based on its dynamically updating routing table

What is the main difference between a wired NIC and a wireless NIC?

Wired NIC uses cables and connectors to transfer data, while wireless NIC connects to a wireless network such as Wifi or Bluetooth.

What is the main function of a modem in a network?

To convert analogue signals from telephone wires into digital signals (0s and 1s) for computers and other devices Signup and view all the answers

What is the key benefit of using a switch in a network?

Error checking and selective forwarding of packets to the correct port only Signup and view all the answers

What is the primary function of a hub in a computer network?

To connect multiple wires coming from different branches and send data packets to all connected devices. Signup and view all the answers

What are the two categories of nodes in a network?

End nodes and Intermediary nodes Signup and view all the answers

What is the key difference between an active hub and a passive hub?

Active hubs regenerate and amplify electrical signals, while passive hubs do not. Signup and view all the answers

What is the function of a switching hub in a computer network?

To analyze data packets and make decisions based on MAC addresses. Signup and view all the answers

What are the two types of media used in computer networks?

Wired Medium (Guided Medium) and Wireless Medium (Unguided Medium) Signup and view all the answers

What is the primary function of a router in a computer network?

To route data packets based on their IP addresses. Signup and view all the answers

What is the primary function of a repeater in a network?

To regenerate and amplify signals to improve network quality Signup and view all the answers

What layer of the OSI model does a NIC card operate on?

Physical and Data Link Layers (Layer 2). Signup and view all the answers

What is a server in a network?

A computer program that provides functionality to another computer program Signup and view all the answers

At which OSI layer do switches operate?

Data Link Layer Signup and view all the answers

Why do hubs send data packets to all connected devices?

Because they cannot filter data and do not have a routing table to store port information and map destination addresses. Signup and view all the answers

What is the primary benefit of using VLANs in network management?

Simplified network management Signup and view all the answers

What are the two types of Gigabit Ethernet implementations?

Two-wire and four-wire implementations Signup and view all the answers

What is the minimum frame length in Gigabit Ethernet?

512 bytes Signup and view all the answers

What is block coding in error detection?

Dividing a message into blocks with added redundant bits to form codewords Signup and view all the answers

What are the two conditions for error detection using block coding?

The receiver has a list of valid codewords and the original codeword has changed to an invalid one Signup and view all the answers

What is the role of the generator in block coding?

Applying rules and procedures of encoding to create codewords Signup and view all the answers

What is the purpose of adding redundant bits in block coding?

To detect errors during transmission Signup and view all the answers

What are the benefits of using VLANs in terms of hardware costs?

Reduced hardware costs by allowing multiple virtual networks to share a single physical network infrastructure Signup and view all the answers

What are the key differences between TCP and UDP in terms of reliability and connection?

TCP is highly reliable and connection-oriented, whereas UDP is unreliable and connectionless Signup and view all the answers

What is the main difference between TCP and UDP in terms of header size?

TCP has a 20-byte header, whereas UDP has an 8-byte header Signup and view all the answers

What are the primary applications of TCP and UDP?

TCP is used for applications requiring reliable transmission, such as FTP, Telnet, and SMTP, whereas UDP is used for applications requiring fast transmission, such as DNS, BOOTP, and DHCP Signup and view all the answers

What is the main difference between TCP and UDP in terms of data transmission?

TCP is stream-based and manages delivery of all data, whereas UDP is message-based and does not guarantee delivery Signup and view all the answers

What is Quality of Service (QoS) in communication networks?

QoS refers to mechanisms that provide predictable or guaranteed performance to applications, sessions, or traffic aggregates Signup and view all the answers

What are the two techniques for achieving good Quality of Service (QoS) in communication networks?

Overprovisioning and Buffering Signup and view all the answers

What is the primary limitation of overprovisioning as a QoS technique?

It is an expensive technique as the resources are costly Signup and view all the answers

What is the main goal of Quality of Service (QoS) mechanisms in communication networks?

To differentiate performance based on application or network-operator requirements or provide predictable or guaranteed performance Signup and view all the answers

What is the purpose of the flow label field in IPv6, and how many bytes does it occupy?

The flow label field is designed to provide special handling for a particular flow of data, and it occupies 3 bytes (24 bits). Signup and view all the answers

What is the purpose of the next header field in IPv6, and how many bits does it occupy?

The next header field defines the header that follows the base header in the datagram, and it occupies 8 bits. Signup and view all the answers

Compare and contrast the hop limit field in IPv6 with the TTL field in IPv4.

Both the hop limit field in IPv6 and the TTL field in IPv4 serve the same purpose, which is to prevent packets from circulating indefinitely in a network. However, the hop limit field is 8 bits in IPv6, while the TTL field is 8 bits in IPv4. Signup and view all the answers

What is the role of the source address field in IPv6, and how many bytes does it occupy?

The source address field identifies the original source of the datagram, and it occupies 16 bytes (128 bits). Signup and view all the answers

What is the role of ARP in communication, and how does it work?

ARP (Address Resolution Protocol) is used to map a logical (IP) address to a physical (MAC) address. It works by sending an ARP query packet, which is broadcasted to all hosts on the network, and the intended recipient responds with its physical and IP addresses. Signup and view all the answers

What is the role of DHCP in communication, and how does it work?

DHCP (Dynamic Host Configuration Protocol) is used to assign IP addresses and other network settings to devices on a network. It works by assigning an IP address to a device from a pool of available addresses, and the device can request a renewal of the IP address when it is about to expire. Signup and view all the answers

How does ARP resolve the IP address of a device to its physical MAC address?

ARP resolves the IP address of a device to its physical MAC address by sending an ARP query packet, which is broadcasted to all hosts on the network, and the intended recipient responds with its physical and IP addresses. Signup and view all the answers

What is the purpose of the payload length field in IPv6, and how many bytes does it occupy?

The payload length field defines the length of the IP datagram excluding the base header, and it occupies 2 bytes. Signup and view all the answers

Study Notes

Physical Components of Computer Networks

NIC (Network Interface Card): A network adapter used to connect a computer to a network, with a unique ID and a connector to connect cables.
- Types: Wired NIC (uses cables and connectors) and Wireless NIC (connects to wireless networks like Wi-Fi and Bluetooth)

Hub

Hub: A multiport repeater that connects multiple wires, sending data packets to all connected devices.
- Types:
  - Active Hub: Regenerates and amplifies electrical signals, suitable for long-distance connections.
  - Passive Hub: Does not amplify or regenerate signals, simplest type of hub.
  - Switching Hub: Analyzes data packets and makes decisions based on MAC addresses, operates on the Data Link Layer.

Router

Router: A device that routes data packets based on their IP addresses, connecting LANs and WANs, with a dynamically updating routing table.
- Divides the broadcast domains of hosts connected through it.

Modem

Modem: A hardware component that connects devices to the internet, converting analog signals from telephone wires to digital form.

Switch

Switch: A multiport bridge with a buffer, performing error checking before forwarding data, and forwarding good packets selectively to the correct port.
- Operates on the Data Link Layer.

Nodes

Node: A computing device that sends and receives network packets, such as computers, security cameras, and network printers.
- Types:
  - End Node: Starting or end point of communication.
  - Intermediary Node: In between the starting or end point of communication, such as switches, bridges, routers, and cell towers.

Media

Media: The link that carries data from one side to another, either wired (guided medium) or wireless (unguided medium).

Repeater

Repeater: A device that regenerates and amplifies signals in computer networks, improving network quality and operating on the Physical Layer.

Server

Server: A computer program that provides functionality to other computer programs, such as simplified network management, flexibility, cost savings, and scalability.

Gigabit Ethernet

Gigabit Ethernet: A high-speed Ethernet standard with a speed of 1 Gbps, minimum frame length of 512 bytes, and operates in full duplex mode.
- Types:
  - Two-wire implementation: Uses fiber-optic cable or STP.
  - Four-wire implementation: Uses category 5 twisted-pair cable.

Block Coding

Block Coding: A method of error detection and correction by dividing messages into blocks, adding redundant bits, and creating codewords.
- Conditions for error detection:
  - The receiver has a list of valid codewords.
  - The original codeword has changed to an invalid one.

IPv4 and IPv6

IPv4: A 32-bit Internet Protocol address, with fields like version, IHL, type of service, total length, etc.
IPv6: A 128-bit Internet Protocol address, with fields like version, flow label, payload length, next header, etc.

Address Resolution Protocol (ARP)

ARP: A protocol that maps logical (IP) addresses to physical (MAC) addresses.
- Process:
  - The sender broadcasts an ARP query packet with the IP address of the receiver.
  - The receiver responds with its physical and IP addresses.
  - The packet is unicast directly to the inquirer using the physical address.

Dynamic Host Configuration Protocol (DHCP)

DHCP: A protocol that assigns IP addresses and other network settings to devices on a network.

TCP and UDP Header Formats

TCP (Transmission Control Protocol): A connection-oriented protocol, slow, reliable, and heavy-weight.
- Header format: 20 bytes, with fields like source and destination port numbers, sequence number, acknowledgement number, etc.
UDP (User Datagram Protocol): A connectionless protocol, fast, unreliable, and light-weight.
- Header format: 8 bytes, with fields like source and destination port numbers, length, and checksum.

Quality of Service (QoS)

QoS: A mechanism that seeks to provide predictable or guaranteed performance to applications, sessions, or traffic aggregates.
- Techniques:
  - Overprovisioning: Providing greater router capacity, buffer space, and bandwidth.
  - Buffering: Buffering flows on the receiving side before delivery.

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Description

This quiz covers the physical components of computer networks, including Network Interface Cards (NICs) and Hubs. It explains the types of NICs and Hubs, their functions, and characteristics.