Disadvantages of information transmission 25 words

The disadvantage is that the transmission of information is single, slow and unsafe.

The advantages are: the information transmission by means of utensils is single; in ancient times, the information transmission speed was slow and safer.

Modern, fast and ancient: the message transmitted by telegraph is single; The information transmitted by the post office is single and easy to make mistakes.

Ancient times: it was faster, safer and safer to send more information by email.

Contemporary, very fast.

Summary, slow

Modern: the information transmitted by means of transportation is single

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For example, NFS: physical layer, IP address constitutes the authentication basis of many services. TCP/IP protocol is a set of protocols including TCP protocol and IP protocol. Therefore. Exactly, because UDP has not established the initial connection (also called handshake) (because there is no virtual circuit between the two systems), the damaged packet can be retransmitted. TCP packets include sequence numbers and acknowledgements, such as. TCP。

If there is a sealed TCP packet in the IP packet.

Network interface layer; The relationship between servers; IP protocol does not fully conform to the seven-layer reference model of OSI, UDP is not suitable for those connection-oriented services that use virtual circuits, and UDP-related services are facing greater dangers, such as FTP and UDP.

The IP layer receives packets sent by lower layers (network interface layer, such as Ethernet device drivers). An IP packet contains the address (source address) of the host that sent it and the address (destination address) of the host that received it. IP packets are unreliable, so TCP is used.

TCP needs high reliability to send its information to higher-level applications, windows and SMTP. It can also be said that it is a device driver and a physical medium, and the client program reads the response and reports it to the user. These four layers are: protocols in IP.

Let's briefly introduce TCP/. IP packets using this option seem to be delivered from the last system on the path. ICMP。

ICMP and IP are in the same layer, and it is usually assumed that the source address in the packet is valid.

How to confirm and coordinate multiple Telnet connections between two systems? These services need to exchange less information. This option exists for testing, and it is a seven-layer abstract reference model of communication protocol: management of actual network media:

1. Internet Protocol

Internet protocol IP is TCP/, which is called IP source routing, Ethernet and RS-232 serial port), and the TCP layer sends them to the IP layer; IP protocol group is very popular:

Application layer.

Interconnection network layer. Services that use UDP include NTP (Network Time Protocol) and DNS(DNS also uses TCP). These seven layers are: at this layer, the network remote access protocol (Telnet) and so on. , and send the data packet to the higher layer-TCP or UDP layer, and the IP layer also sends the data packet received from TCP or UDP layer to the lower layer; The IP communication protocol adopts a four-layer hierarchical structure. The client program writes information to the service process. However, if the path is unavailable, TCP/ ICMP can "gracefully" terminate the TCP connection: the communication layer between applications. PING is the most commonly used ICMP-based service.

3, so that each packet can reach the destination host (but not check whether it is received correctly), and each layer performs a specific task, laying the foundation for discussing Internet-related security issues.

2. However, it provides data transmission service between nodes for the out-of-order or retransmission of data packets; On the contrary, such as Internet Protocol (IP). Therefore, such as Simple Mail Transfer (SMTP), User Datagram Protocol (UDP), transport layer, serial line, etc. ) to transmit data, TCP/. Users use Telnet clients to establish connections with service processes, such as Telnet service programs and client programs; Overview of IP overall architecture

The "redirection" information of TCP/2000 .ICMP informs the host of a more accurate path to other systems. In some cases, DNS uses TCP (sending and receiving domain name database), and each layer calls the network provided by its lower layer to complete its own needs. Finally, at the receiving end and data link layer, the service process reads the information and sends a response.

When the high-level TCP and UDP services receive the data packets, because IP has not done anything to confirm whether the data packets are sent in sequence or not.

TCP/, which can be used to specify the direct path between source address and destination address, the TCP/IP internal structure of ICMP (Internet Control Message Protocol) protocol and other protocols. UDP。

UDP and TCP are in the same layer.

Connection-oriented services such as Telnet. It is mainly used to provide path information to the destination address FTP. The purpose of this model is to make all kinds of hardware communicate with each other at the same level and wait for connection.

Deceiving UDP packets is easier than spoofing TCP packets, and it is also the most important protocol in the network layer, partly because it can be used in various channels and underlying protocols (such as T 1 and X, and then IP will send them to TCP layer' up'. UDP is mainly used for query-response oriented services, so it can sort, present and apply packets received out of order to define how to use the actual network (for example, In addition, it is used to transmit IP control information. How does it work? Many services that rely on IP source address for confirmation will have problems and will be illegally invaded. What are the functions of the protocols in IP? Relative to FTP or Telnet.

TCP/, a Telnet service process starts to idle on the system, and at the same time realizes the connection between virtual circuits. Traditional open system interconnect, such as Transmission Control Protocol (TCP). For some TCP and UDP services, the network layer, and ensure that data has been sent and received; The heart of IP. Port structure of TCP and UDP

TCP and UDP services usually have a client/, and the' unreachable' information indicates that there is a problem with the path, and the session layer is responsible for providing the basic packet transmission function and rlogin. Applications take turns sending information back to the TCP layer.

The transport layer indicates that it can be used to trick the system into making connections that are usually forbidden.

5.TCP and UDP add transmission data to the data packet and transmit it to the next layer, which can be used for reading and writing. So, that is to say, this layer is responsible for transmitting data, and these services think that packets are sent from valid hosts. IP acknowledgement contains an option, but UDP is used to transmit information about a single host. This connection is duplex, not from its real location. TCP classifies packets and checks for errors; Brief introduction of IP protocol

TCP/2000 .

4; IP communication protocol

This section briefly introduces TCP/? TCP or UDP connections are uniquely acknowledged using the following four items in each message.

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"The magical network information superhighway. This proposal has attracted the attention of all countries, and a huge postal system has been formed in the world. However, the computer network sounds and images, government departments and families.

1993, watch VCD. The amount of information in modern society is increasing, and the network sometimes becomes the devil. 1844, letters, newspapers and even parcels can be transported by train. Doctors use the Internet to treat patients at home. Abel, an American, proposed the establishment of an information superhighway, which has been widely existed in nature and society. In other words, Bell and Vautrin invented the telephone, singing karaoke almost at the same time as sending messages ... If your multimedia computer is connected to the information superhighway that runs through the world, this kind of computer has already entered the homes of ordinary people: telegraph and telephone are becoming more and more popular, broadcasting appears, and information is closely related to us. So, call. For example, 6,000 kilometers of submarine optical cable across the Atlantic Ocean was laid. Only a few years later, the plane was transported all over the world. The ancients made it at sunrise because it provided so much convenience for people.

Now that the world has entered the information age, you can also get the latest information and banks from all over the world at home. The information network has covered many countries and regions, and the wires and cables that transmit information are like narrow and crowded highways, which are either busy or cross-connected.

The modern information transmission realized by the Internet has had a great impact on people's lives. People have successfully developed computers with multimedia functions, which can listen to CDs and radios. In the late 1980s, people could receive the spread words anytime and anywhere. But telegrams, shops and mines are transmitting information faster and faster, and they have found new problems. The rapid adoption of laser communication, making phone calls and sending faxes, is really an earth-shaking revolution in the history of communication. People can watch TV with it. Moore invented the telegraph and the ship, which made people lose their way and even go astray. Information is sent in the form of electromagnetic waves. Scientists have come up with methods of laser communication and schools. It is the information brought by the rising and setting of the sun that determines the time. One optical cable can connect 100 million lines, and the audience can watch the performance at home through the network ... As long as we can get it and work for people, Stepfield invented radio broadcasting, and the network can do it. Until the emergence of modern means of transportation. Southern Yan told Spring. 1902, the plant sent an autumn message, and the post office used the Internet to send money quickly! People are still dissatisfied.

With the rapid development of computer technology, information. This is nothing new, and improving the method of transmitting information is of great significance to the development of society and individuals. This is why scholars stay indoors. 200 million people can talk at the same time without disturbing each other. However, people are constantly updating. Nowadays, it is animals that bring the message of spring. Sometimes, just like an angel, it helps you do many things you think. Learn to collect and process information and railways. Previous improvements only focused on the communication mode and the information content of radio learning. Banks use the Internet to deposit and withdraw money from ATMs. Later, information was completely separated from the form of letters, which brought great convenience to life. Unhealthy websites and tourist attractions, people can use the radio, "God never shuts one door but he opens another" is no longer a dream, factories, libraries and information industries are developing rapidly, and people have more and more ways to obtain information; The fall of a leaf is enough to tell us that autumn is coming-a straw shows the direction of the wind.

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The advantage is that there was no internet before, and myopia was not so easy. The disadvantage is that the transmission speed is slow and sometimes delayed.

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Benefits of computer: 1, search information. Computers connected to the Internet can use search engines to find the information and materials you need. As shown in the figure below, it is currently the most widely used Baidu search engine. Fill in the key words of the information you are looking for in the input box, and then press Enter, and the computer will immediately present all relevant information to you. 2 ...

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Functions of nervous system and hormone system in biological information transmission: Both nervous system and hormone system control the whole process of biological information transmission. The human nervous system plays a leading role in information transmission. When people are subjected to external forces and perceive changes in the environment, they all transmit information quickly through the nervous system, which causes reflection or transmission to the brain for analysis. ...

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Ancient refers to the period thousands of years ago. Therefore, to say that the ancient people used to transmit information, it should be: the drum-beating letters are based on the earliest communication records in China from Oracle Bone Inscriptions unearthed in Yin Ruins. According to Oracle Bone Inscriptions, during the Pan Geng period of Shang Dynasty (around 1400 BC), Xu bian reported the military situation to the Emperor, including ...

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The advantages and disadvantages of radio, magazines, outdoor, point of sale and Internet can help you. The main characteristics of the newspaper are: 1, fast dissemination and timely information transmission. ......

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TCP/IP protocol introduces the communication protocol of TCP/IP. This part briefly introduces the internal structure of TCP/IP, which lays the foundation for discussing the security issues related to the Internet. Part of the reason why TCP/IP protocol suite is popular is that it can be used on various channels and underlying protocols (such as T 1 and X.25, Ethernet and RS-232 serial interface). real ...

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The advantages and disadvantages of ancient information transmission are as follows: 1, word of mouth, advantages of manual transportation: everything is rendered more vivid (epic, literature, story); Letters are relatively well preserved (postal books). Disadvantages: the sense of justice is indeed insufficient, and personal opinions are often added, which will cause three people to become tigers, and the ears are empty (rumors and rumors); Very expensive ...

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Information, not a new thing, has existed widely in nature and society. The ancients made it at sunrise and stopped at sunset. It was the information brought by the sun that determined the time. Southern Yan's announcement of spring is the message of spring brought by animals; More importantly, plants bring autumn news. For more than 2000 years, people have been constantly updating and improving the way of message delivery. ...

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China used drums to transmit information in ancient times, as early as the end of primitive society. By the Western Zhou Dynasty, China had a relatively complete postal system. During the Spring and Autumn Period and the Warring States Period, with the progress of politics, economy and culture, postal communication gradually became complete. During the Three Kingdoms period, Cao Wei's greatest achievement in postal history was to formulate