Chapter 1 - Network Models

Question 1

Where does a hub send data?

Answer 1

Data comes into the hub through one wire and is then sent trhough all the remaining wires.

Question 2

What uniquely identifies every NIC?

Answer 2

The MAC (Media Access Control) adress.

Question 3

What Windows utility do you use to find the MAC address for a system?

Answer 3

ipconfig /all

Question 4

A NIC sends data in discrete chunks called ____.

Answer 4

Frames.

Question 5

Which MAC address begins a frame?

Answer 5

It starts with the receiving MAC.

Question 6

A frame ends with a special bit called the frame check sequence (FCS). What does the FCS do?

Answer 6

Error detection. It uses the CRC (cyclic redondancy check) algorythm.

Question 7

What format is used to represent a MAC adress.

Answer 7

A MAC adress is a 48 bit address represented by 6 bytes (2 Hex).

Question 8

Which layer of the TCP/IP model controls the segmentation and reassembly of data?

Answer 8

The transport layer.

Question 9

Which layer of the OSI seven-layer model keeps track of a system connections to send the right response to the right computer?

Answer 9

the session layer.

Question 10

Name the 7 OSI layers.

Answer 10

Layer 7 Application
Layer 6 Presentation
Layer 5 Session
Layer 4 Transport
Layer 3 Network
Layer 2 Data Link
Layer 1 Physical

Question 11

What does UTP cabling stands for?

Answer 11

Unshielded Twisted Pair.

Question 12

What is a NIC?

Answer 12

A NIC is a Network Interface Card. It operates on Layer 1 & 2 and is used to interface the network connection to the computer system.

Question 13

What is a OUI?

Answer 13

Organizationally Unique Identifier. It is the first 24 bits of the MAC address.

Question 14

What is the difference between MAC-48 and EUI-48?

Answer 14

EUI-48 stands for Extended Unique Identifier. It is the latest IEEE nomenclature for MAC-48, but every tech still calls it a MAC address.

Question 15

What is a frame?

Answer 15

A frame is a layer 2 data chunck. It is composed of the recipient MAC address, the sender’s MAC address, the type, the encapsulated Data and the FCS. It is 4 bytes long. A frame has a maximal size of 1500 bytes.

Question 16

What are the two aspects of the NIC?

Answer 16

The NIC has the Logical Link Control (LLC) and the Media Access Control (MAC) aspect. The LLC provides flow controls and talks to the drivers while the MAC which create, sends and receives the frames.

Question 17

What is a logical address?

Answer 17

A Logical address is an IP address.

Question 18

What is a packet?

Answer 18

A packet is a unit of data transmitted over a network. It consists of two main parts: the header and the payload. The header contains information about the packet, such as the source and destination addresses, sequencing information, error-checking data, and protocol details. The payload carries the actual data being transmitted.

Packets are essential for efficient data transfer in computer networks. They allow large files to be broken down into smaller, manageable units, improving network performance and reliability. The process of breaking down and reassembling data into packets is known as packetization. Once packets reach their destination, they are reassembled in the correct order to reconstruct the original data.

Question 19

What is segmentation and reassembly?

Answer 19

Segmentation is the process of breaking down large blocks of data into smaller segments for efficient transmission over a network. These segments, or packets, are easier to handle and transmit compared to transmitting the entire block of data at once. Segmentation is a fundamental aspect of packet-switched networks, where data is transmitted in discrete packets.

Reassembly is the counterpart process to segmentation. Upon reaching their destination, the individual segments or packets are reassembled in the correct order to reconstruct the original data. This process ensures that the data transmitted over the network is accurately reconstructed at the receiving end.

Question 20

How is a network able to talk to multiple devices at the same time?

Answer 20

The secret to multiple connection is within the layer 5 (session). The session layer assigns port to track connections.

Question 21

Where does high level encryption exists?

Answer 21

Protocols like SSL and TLS exists at the presentation layer (layer 6). The presentation layer interface the application layer and the session layer and translates the data between them (e.g. encryption).

Question 22

What’s the role of the application layer?

Answer 22

The application layer in the OSI model serves as the interface between the network and the software applications that need network services. Its primary role is to provide network services directly to end-users or applications. This layer enables communication between different software applications, handling tasks such as data exchange, encryption, and compression.

Question 23

Explain encapsulation and decapsulation.

Answer 23

Encapsulation is the process of wrapping data in a specific protocol header as it moves through the layers of the OSI model. Each layer adds its own header to the data, forming a packet or frame. This encapsulation provides structure and additional information to the data, facilitating its transmission across the network.

Decapsulation is the reverse process, occurring at the receiving end. As data travels up the OSI model layers, each layer removes its respective header, extracting the original data. Decapsulation ensures that the data is appropriately processed and delivered to the intended destination.

Question 24

What are the 4 layers of the TCP/IP model?

Answer 24

Layer 4 Application
Layer 3 Transport
Layer 2 Internet
Layer 1 Link/Network Interface

Question 25

What is the structure of a TCP segment?

Answer 25

Destination port, Source port, Sequence number, Checksum, Flags, Ack, Data.