Table of contents
1. Understand the computer network around you
1.2 Classification of topology in the network
2. Understand the network model
2.2.2 Data encryption and decryption
2.4 Data encapsulation and decapsulation
2.4.1 Data encapsulation and decapsulation
3. Understand the transmission medium
3.3 Media for network communication
Preface
This article provides an analysis of some exercises in the network skill tree, including understanding the computer network around you, understanding the network model, and understanding the transmission medium. The article not only provides the analysis of these three parts of the exercises, but also some of my own understanding, which friends can refer to.
1. Understand the computer network around you
1.1 Common network equipment
The following is a brief description of some common network devices and their functions and roles:
1. Router: used for forwarding and routing data packets between networks so that different networks can communicate with each other.
2. Switch: used to forward data packets within the LAN. It can identify the MAC address of the target device and forward the data to the target device.
3. Hub: Connects multiple devices together and delivers data packets to all connected devices through broadcast. However, it has been replaced by switches.
4. Network Firewall: Used to monitor and control network traffic, and can detect and block unauthorized access and network attacks.
5. Network Attached Storage (NAS): Provides shared network storage space for storing and accessing files and data.
6. Network Printer: A printer connected through a network, allowing multiple computers to share printing devices.
7. Network Camera: A camera device that monitors and transmits video over the network, allowing real-time video to be viewed remotely.
8. Network Wireless Access Point: Connects wireless devices to wired networks through wireless signals to provide Wi-Fi access.
9. Modem: Converts digital signals into analog signals and is used to establish a connection between a computer and an Internet service provider.
10. Gateway: used to connect different types of networks, act as a bridge between two different networks, and realize the conversion of data formats and protocols.
The above-mentioned devices are only a small part of the network. In fact, there are various other devices, such as Network Accelerator, Load Balancer, etc. These network devices play an important role in composing and managing modern network infrastructure. They work together to provide stable, efficient and secure network connections and communications.
topic:
Which of the following are common intermediate devices in the network:
- router
- switch
- server
- hub
A.1,2,3
B.2.3.4
C.1.2.4
D.1.3.4
Analysis: Choose C.
Servers are not intermediate devices in the network. A server is a computer or device used to provide various network services. It plays the role of storing, processing and distributing network resources. Servers are used to host websites, applications, databases, etc. and provide these services to clients. Intermediate devices mainly include routers, switches and hubs, which are network devices used to manage and forward data.
Therefore, the answer should be choice C.
1.2 Classification of topology in the network
Network topology refers to the physical and logical structure of the connections and layout of devices in a computer network. The following is a description of common network topology classifications:
1. Star topology: In a star topology, all devices are connected together through a central device such as a hub, switch, or router. The central device is responsible for forwarding data packets, and communication between devices occurs through the central device. This topology can provide better performance and management capabilities, but the central device becomes a single point of failure.
2. Tree topology: Tree topology is formed by connecting multiple star networks through a hub or switch. This topology effectively scales the network and allows multi-level connections. The top of the tree structure is a root node, starting from the root node and extending to the end device through branches and sub-nodes. Tree topology is a common choice in large networks.
3. Mesh topology: In a mesh topology, each device is directly connected to other devices, forming a network-wide interconnection structure. This structure allows communication between multiple paths, providing redundancy and high availability. Mesh topology helps with scalability and fault tolerance, but has higher cabling and management complexity.
4. Ring topology: In a ring topology, devices are connected in a ring, and each device is connected to two adjacent devices. Data is transmitted through the loop, with each device receiving and transmitting data. Ring topologies allow for relatively low cost and simple connections, but if one device in the ring fails, the entire ring fails.
These topologies are often used in computer networks, and each topology has its own characteristics and applicable scenarios. In real networks, hybrid topologies can also be used to meet specific needs. Choosing the appropriate topology depends on factors such as network size, performance requirements, reliability needs, and management complexity.
topic:
Which of the following are shape classifications of network topology?
- star
- tree type
- mesh
- ring type
A.1,2,3,4
B.2.3.4
C.1.2.3
D.1.3.4
Analysis: Choose A.
Based on the previous article, it is obvious that this question must be selected.
2. Understand the network model
2.1 Overview of network model
topic:
Network protocols are rules , conventions and standards developed for data exchange
2.2 OSI model
2.2.1 OSI reference model
topic:
The OSI reference model is divided into several layers from high to low: application layer, presentation layer, session layer, transport layer, network layer, data link layer, and physical layer.
2.2.2 Data encryption and decryption
topic:
Encryption and decryption of data are functions of the presentation layer in the OSI reference model
2.3 TCP/IP model
The TCP/IP model is a network communication protocol system, which is the basis of the basic communication architecture of the Internet. The TCP/IP model consists of four levels:
1. Network Interface Layer: Responsible for defining how data is transmitted in the physical network, such as the standards used by network cards, cable types, etc.
2. Internet Layer: Responsible for processing the routing and forwarding of data between different networks, mainly including the IP protocol and responsible for the transmission of data packets.
3. Transport Layer: Responsible for providing reliable end-to-end data transmission, mainly including TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
4. Application Layer: Provides interfaces for network-based applications to access the network, including HTTP, FTP, SMTP and other protocols.
2.3.1 TCP/IP protocol model
topic:
The TCP/IP protocol model is divided into several layers from high to low: application layer, transport layer, Internet layer, and network interface layer.
2.3.2 TCP/IP
topic:
Which of the following statements about the TCP/IP protocol is incorrect?
A.TCP/IP protocol refers to TCP protocol and IP protocol.
B.TCP/IP transmission protocol is strictly a four-layer architecture, including the application layer, transport layer, network layer and data link layer.
C.TCP/IP protocol refers to a protocol cluster composed of FTP, SMTP, TCP, UDP, IP and other protocols.
D. The full name of TCP/IP protocol is: Transmission Control Protocol/Internet Protocol, Transmission Control Protocol/Internet Protocol.
Analysis: Choose A.
TCP/IP protocol refers to a protocol cluster composed of FTP, SMTP, TCP, UDP, IP and other protocols, not just TCP and IP protocols. It is a set of interrelated protocols, including TCP and UDP protocols at the transport layer and IP protocols at the network layer.
Therefore, the statement in option A is incorrect.
2.4 Data encapsulation and decapsulation
Encapsulation and decapsulation of data are two key steps performed during data transmission in network communications.
1. Encapsulation: At the sending end, data is passed down from the application layer, and the required header and tail information are added layer by layer through the transport layer, Internet layer and network interface layer to form a complete data packet or frame. The encapsulation of each layer defines specific header and trailer formats in the protocol, and adds data from the previous layer to the header or trailer. In this way, the data is divided into small packets during transmission, and necessary control information is added to confirm and ensure the reliability of the transmission.
2. Decapsulation: At the receiving end, the data is decapsulated layer by layer starting from the physical layer, removing the header and trailer added by each layer, and restoring the data to the original application layer data. Reversely, each layer extracts the required information from the packet according to the rules specified in the protocol and passes it upward layer by layer until it reaches the application layer. This process is the reverse process of packet transmission and routing in the network.
The purpose of the encapsulation and decapsulation process is to enable data to be transmitted in the network while providing the necessary control and information to ensure that the data reaches the destination in the correct order and manner, and to ensure the integrity and reliability of the data.
2.4.1 Data encapsulation and decapsulation
topic:
Which of the following statements about data encapsulation and decapsulation is incorrect?
A. In a layered system, data is encapsulated multiple times in the process from the top layer to the bottom layer.
B. A data packet in the upper layer may be encapsulated into multiple data packets in the lower layer.
C. The sender encapsulates the data in a certain format, and the receiver unblocks the data in a certain format.
D. When encapsulating, the data of the upper layer becomes the header of the lower layer.
Analysis: Choose D.
In network communication, data encapsulation is to add upper-layer data to lower-layer data packets to form a complete data packet, which is then transmitted through the network. In each network layer, corresponding header information is added to identify and control the transmission of data packets. In this process, no upper layer data becomes the header of the lower layer.
Therefore, the statement in option D is incorrect.
3. Understand the transmission medium
3.1 Data transfer rate
There are many units of data transfer rate, common ones include:
1. Bits per second (bps): Indicates the number of bits transmitted per second.
2. Kilobits per second (kbps): Indicates the number of kilobits transmitted per second, equal to 1000bps.
3. Megabits per second (Mbps): Indicates the number of megabits transmitted per second, equal to 1000kbps.
4. Gigabits per second (Gbps): Indicates the number of gigabits transmitted per second, equal to 1000Mbps.
5. Terabits per second (Tbps): Indicates the number of terabits transmitted per second, equal to 1000Gbps.
In addition, there are other units such as bytes per second (Bps) and kilobytes per second (KBps), which are data transfer rate units based on the number of bytes.
topic:
The unit of data transfer rate is:
Please choose from the options below
A.bit
B.byte
C.bps
D. Drown
Analysis: Choose C.
Based on the previous article, it is obvious that C.bps is selected for this question.
3.2 Communication methods
topic:
At the same time, the channel communication method in which both communicating parties can send data at the same time is:
Please choose from the options below
A. Hansouko communication
B.Datagram
C.Full duplex communication
D.Simplex communication
Analysis: Choose C.
Half-duplex communication (A) only allows the communicating parties to send and receive in different time periods, not at the same time; datagram (B) is a connection-oriented communication method, not a method for sending data at the same time; full-duplex Work (C): Allows the sender and receiver to conduct two-way communication at the same time, and can send and receive data on the same channel at the same time; Simplex communication (D) only allows data to be transmitted in one direction, and cannot conduct two-way communication at the same time.
Therefore, the correct answer is C. Full-duplex communication.
3.3 Media for network communication
3.3.1 Transmission media
topic:
Among the following transmission media, the ones that are not affected by electromagnetic interference or noise are ( ):
Please choose from the options below
A. Coaxial cable
B. Optical fiber
C. Communication satellite
D.Twisted pair
Analysis: Choose B.
Optical fiber transmission uses the principle of refraction of light to communicate through the transmission of optical signals inside the optical fiber, which is not affected by electromagnetic interference. In contrast, electromagnetic waves can interfere with the accuracy and stability of transmitted signals. For example, in copper cable or radio transmission, electromagnetic interference or noise may cause a degradation of signal quality. Therefore, optical fiber is a relatively interference-resistant transmission medium.
Therefore, the answer should be B. Optical fiber.
3.3.2 Twisted pair
topic:
The line sequence of the T568B standard commonly used in twisted pair production is ( ):
Please choose from the options below
A.Orange-white Orange Green-White Green Blue-White Blue Brown-White Brown
B.Orange-white Orange Blue-White Green Green-White Blue Brown-White Brown
C.Orange-white Orange Green-White Blue Blue-White Green Brown-White Brown
D. Green White Green Orange White Blue Blue White Orange Brown White Brown
Analysis: Choose C.
The T568B standard line sequence commonly used in twisted pair production is: orange-white, orange, green-white, blue, blue-white, green, brown-white, brown.
Therefore, the answer should be choice C.
Summarize
This article only provides an analysis of the answers and some personal understandings of the exercises. If you feel something is wrong or wrong, you can discuss it in the comment area. I hope you can give me some advice. The content of this article is simple. For detailed information and more knowledge points, please check the reference materials in the network skill tree.
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