Skills no.2: learn to use logic operator. Below is a search engine of commonly used logic operation series symbols.

also is logic and, with the two key words into the plus a, only at the same time Lenovo Thinkpad SL500 battery satisfy the two key words matching to effective, and only satisfies one’s will be excluded. Such as we type “computer ten calculation”, the “computer” in inquires the “fruit will not contain” calculation “rule out the results.

also, if the logic is between two key words with minus, then its meaning for connection contains the first key words but in the result of having the second key word not. For example we type “computer a calculation”, it is the result of inquires “computer” will not contain “computing A”’s role is to remove the search results, improve not the correlation of search results.

when two keywords using another operator together, and want to take them as a group, the two words, add parentheses. For example we can type “(for a computer program design calculation) ten ( to search for “computer”, do not contain bag contains “calculation” “but at the same time contain” design program “site.

But instead of all the Numbers and letters to the deformation of the retrieval, spelling words or not sure of a key word. Such as type “electric query result can contain computer after, film, TV, etc.

enclosed in double quotation marks to accurately match the words said, not including evolution form. Such as we type with quotes “DianNaoBao”, the “average computer intelligence” interest will not believe in results in appear.

“T:” and “0:” before the keyword plus t:, search engine will only inquires the website names, and before the keyword and u: ‘the search engines will only inquires the address (URL). For example, we would like to check “DianNaoBao” web site, if type key word “DianNaoBao” (don’t add double quotation marks), the search results will include DianNaoBao, computer offer many related web sites; If the key word for the quotes “DianNaoBao”, then the corresponding results will be less, and if we type many of the key word for “t: DianNaoBao”, the result is very clear that inquires.

No.3: click on search results skills before thinking. A successful search consists of two parts: the correct search keywords, useful search results. In you click on any of the search results quickly, before to analyze your search results, web site, the title, will help you choose the more accurate and fruit, help Asus F3 battery you save a lot of time. Of course, exactly which one is what you need, depending on what you’re looking for, the quality of the content and evaluation network authority is the search of heavy to steps.

A successful search also often is by several times of search, if you search content not familiar, even search expert, also can’t guarantee first search to find want to content. Search experts will be the first to use simple keywords test, they will not be busy carefully check every search results, but first from search results page for more information, and then design a better keywords to search, so repeated DuoCi later, can design the great search keywords, also can search to the satisfaction of the search results.

Skills: good at the four correct your mistakes.

Often happen: you seem to have efforts to search, but still not find the answer to the need. This time, please don’t give up, carefully review inspection to check your search process, perhaps just because a small mistake. A look at the search, and no could be your own search after you review strategy for success. After

The steps below describe beginners search when prone to make five mistakes and solve party method, it is because you often make these mistakes, so you always get useless, absurd or no meaning of the search results.

Common mistakes 1: wrong character

Often happen a mistake is the key words, you input contains wrong character. The wrong key words natural retrieval out the wrong results. So whenever you feel some content online should have a lot of, but not when the search, you should check whether there is a wrong word. Don’t

Common mistakes 2: key words too common

Search engine to search of common words defects, because these words exposure rate is too high, that appear in millions of web pages, so they in fact can’t be used to help you find what useful content. For example, a search for “phone” that there are millions of websites offer with the “telephone” relevant information from the Internet to retailers to a personal phone call yellow pages telephone number code. So when the search results too much mess, you should try to use more keywords to search, not or minus signs used too general vocabulary to search, design similar to the one “Shanghai commonly used phone” of this special search keywords, will give you really useful results. Of course, if you want to find a string of auto web site or a string of like? 3 nets stand, then use “car”, “fat” search is correct.

Common mistakes 3: polysemous word

Should be used with care, such as jokes search ” Yang”, you want to find information on earth is an island in the Pacific Ocean, a famous coffee, or a computer language? Search index is holding a can’t understand identify the polysemous word. The best way to solve it is, in the search before asking themselves the question, and then used the phrase, DuoGe keywords or in other words language to replace polysemous word as a search keywords. Such as using “Java Indonesia,” “Java coffee brown”, language “search respectively to meet MSI U90 battery different needs. Common mistake 4: don’t lose key words, what want to lose any of the other search failure a common reason is similar to such search:” modern love story, the lyrics “, “LiaoShen evening news in the issue of shenyang condition”, “the bell of all sorts of figure in car sheep”, “Shanghai to chengdu train schedule”.

Net friend wrong to think that a search engine is a good waiter, actually search led is holding a mechanical, and when you use the keyword search, it will only take contains the close of the web page to find out the key word, not at all the content on the web for what it is.

And the problem is, not a web page will contain “modern love story, the lyrics” and “Shanghai to chengdu train timetable” such key words, households with search engine to also can not find this web page. But the real contains the content you want to find the web page, should contain the keywords is “modern love story” and “the lyrics”, “Shanghai”, “chengdu”, “column car”, “a timetable”, so you should such search: “modern love story, the lyrics”, “LiaoShen evening news shenyang offering”, “the bell sheep car design”, “Shanghai chengdu train moment when table”.

Understand now? Don’t use your heart to DaBaiHua to search, when the search and too little or even no fruit, you should enter the keywords to search more simple, guess you find in the website of the test may contain the keywords, and used those keywords search. 5: common errors in the wrong place search

On July 23, 2001, the day when the university entrance exam FaBang, each big search engines have more than 1 million times more with the university entrance exam score review relevant search. Students don’t know, search index from grab web pages, holding a analytical, indexes to provide retrieval is a cycle, each search engine information from a thoughtful lag cycle in January, so find the latest range content should be the go watch the news, with a search engine is can’t find the latest content, can find only a week or a month ago content. In addition, search engine to dynamic content, such as: BBS, database contents frame structure, and with the web page retrieval ability is weak, so this kind of information are to share a search engine, but should go to the website, however, when looking for looking for related websites search engine is the task of the artists.

No matter when, when you can’t get or get unexpected search results, remember to check your search keywords, analysis with the search results, understand what happened, and you may find and a need to avoid search errors.

Search engine is a good thing, master the application skills, you’ll see that the Internet than imagined wonderful.

The Internet for human provides a platform of communication and the support of multimedia, also make it very naturally become human game space.

And the traditional game network game, compared with its own characteristics:

(1) well made, the picture is beautiful.

Love beautiful heart, the person all has, perhaps real society see so beautiful picture, had to virtual social experience in……. The network game, figure as delicate, grand, beautiful scene. To attract people’s attention, role playing, meet different people with different psychological.

(2) props, many different function

Often hear of network game trigger line trading, so-and-so spent several yuan to buy the game of a severe (of the instrument, can let people take out money to buy these virtual things, so it’s really not magic. In the network game, in addition to the usual equipment, the often of virtual currency outside, the most attractive, I’m afraid is the dragon head but no tail items, the knife, the sword, names are various and purpose is a, attract you to find. Of course, these items are the bad, indeed, you can get most people, this is also the invincible Lenovo Y330 battery before meet the most people’s vanity.

(3) can DuoRen and participation

A lot of people like the network game’s a important characteristic, is that it can DuoRen and play together in a different place in the same game. The network has connected all over the world, network swim would allow play where players play together, in this way, the player can form a group to play, improve the unity cooperation spirit.

(4) bring forth

Network game with the original on the hard drive their game a little bit different, very quickly, all kinds of map update, kinds of items continuously appear, and constantly for players to shine at the moment, the feeling and new things. So, to keep the game continued the newness.

(5) the diversity of the role

Each network game, all have the choice of what role, the elves ah, ah, ah, warrior monk such, can satisfy the psychological needs of different people. Also, each character has the tools, characteristics are different. Each role-play, would give players with psychological experience not.

(6) important communication function

Communication function is the network game’s soul, no communication, network game will greatly those values. The most let us forget to return, is the communication between human beings. This is why yao various BBS constantly gushed out, and so DuoRen, bubble in the above reasons. Network communication function in the game and BBS is different, first, a more perfect avatar, BBS is a personalized small head, there is also a more attractive signature. And network in the show, or swim warrior, or wizard, or Taoist, dress up, the expression, manner, all on the screen to come to show it. Raise your hand, meditation, bend, laugh, cry, angry, DuoZhong diversity, more can attract people to participate. Second, network game in human raised with, but also people like playing online games reasons. When you are fully equipped, take a little when the weapons of the world; When you beat up, when the monster with; When you and other players to fight (known as PK) and make him HP CQ60 battery be defeated and flee, that kind of satisfaction maybe just can’t language to describe. Again, the player in the monsters and with other play home or fighting, often with others, if both parties through tacit cooperation, that feeling is beat each other is very good. Both training team spirit, and enhance the affection.

Network game there are several types, each of which has its fans. At present, the domestic main to network game fantasy game, martial arts have game, Q edition game, casual games four categories of leadership network game, each type of mainstream game all have their own representative work, the fantasy game world of warcraft rank high on the list, leisure type of the PaoPaoTang “knight-errant game, followed by big masterpiece, the love JianXia II, ranked third, Q version of the game” big words west II, “was fourth occupied.

The game of chess platform, because realize technology relatively simple, a hair with low cost, is the earliest forms of the game in network, it is also the difficulty to fit is not high, the gelling degrees to the user is not enough, “let the game of users pay also relatively difficult, so, people choose to play for free on the Internet. The game against platform, are usually are a hit on single, and have the game players of the game by, the popular situation has been completed by LAN game itself, the game itself is not platform providers, because the users of all pay intend to is not high also. Leisure operation the development of the game than the game of cost platform to be much higher, each time the user game time consuming also relatively long, like now the larger game belong to this type.

Although it has not yet been determined said network game is good or bad, but should admit it created a new industry, which is now the most popular domestic development of an industry, online game production, because more and more people like this and not see the opponent is quantity: network games . According to statistics, China’s online game every year all the speed of growth in the number of more than 100%, and online game market to 200% growth in the size of the

(2) streaming media

1. The concept

The so-called streaming media refers to the flow in the way of transmission Internet/Interanet broadcast media formats, such as audio, video or multimedia files. People used to watch movies on the network or listening to music, must be the whole video download and stored in a text on your local computer, then you can watch. And the traditional broadcast way different, streaming media in the play is not download the complete documents before, only will start of the deposit, in computer memory capacity of data packets to cache and made the media data correctly output flow media side transmits data flow as broadcasting, this saves download waiting room and storage space. Streaming media flow of data transfer at any time at any time, just play in when beginning a delay. Obviously, streaming media key realization technology is streaming transmission, streaming transmission mainly refers to the audio and video and 3 d media, and other multimedia files Dell 1500 battery through specific compression as an analytical way compressed package, video server to users by computer the sequence or real-time transmission. In the current transmission mode system, users do not have to adopt like with the file download way until all the download is complete, but only after A few seconds or dozens of seconds of time delay can start in user’s computer equipment on the compression using unpacks A/V, 3 D and other multimedia file decompression play and watch after. Now the rest of the multimedia files in the background in the server will continue to download. And the single phase, this way than download of multimedia files downloaded while seeding of the edge flow not only start ii. The transmission delay “greatly shortened, and the demand of buffering capacity of the system was greatly reduced, extremely the earth to reduce waiting time for users.

Streaming media can side as broadcasting, and download the print media different. Streaming media’s largest interactive features, this also is the Internet’s most attractive place. Streaming data flow has three characteristics: continuity, real-time, timing, namely the data flow sex has strict timing relationships before and after. In addition to the broadband network, streaming media technology can widely used in other network, such as wireless streaming media transmission is 3 G network is one of the main application. In the network, the flow of NGN media also play important roles. Streaming media application type: streaming media application can according to transfer mode, real-time, interaction, roughly divided into DuoZhong type.

According to the classification of streaming media, common applications mainly has: video on demand, video, video surveillance, video broadcast meeting, remote teaching, interactive swim show, and other. In short, currently based on streaming media applications very much, developing very fast. Rich flow media application to the users, very attractive in solving the restriction of streaming media key technical problems, shut after can be expected, the streaming media application should become the mainstream of the future network applications.

China public computer Internet

JinQiaoWang namely jitong communication, has already formed a satellite for the backbone of the Internet, there are four independent international exports, in the whole nation already built 100 DuoGe satellite station, more than 300 are the individual users;

China’s education scientific research nets, networking in universities of more than 100, with 64 KBPS already built, DDN line of China’s eight regional network connection to the center of the backbone;

China science and technology network as the science Lenovo G530 battery and technology, scientific management and its users

He related government administration department of main network of national;

Unicom public computers, the Internet for Internet service providers and the Internet content providers, to the end of December, 1998, backbone network has covered all the provinces, city network nodes in 230 cities across the country.

Different from the U.S. proposed national information infrastructure NII plan,

China has no national information infrastructure, and in the formulation of the national informatization is the idea.

Chinese scholars from the 1980 s began to spread information research. In 1997 the national work conference held the first information. In January 2001, the state council established the national interest letter work leading group, vice premier wu bangguo as leader, ministry of information industry minister WuJiChuan appointed deputy leader.

“Information” first appeared on national leaders in speech is 1989 years of jiang zemin article “on the world of electronic information industry development in our country and the characteristics of the development strategy of the problem”, said: “the information service industry will have a large scale of development, it has become an important symbol of the economic information.”

First appeared in the central file information is on 28 September 1995, the communist party central formulated in about the national economic and social development in the ninth five-year plan and 10 years the long-term goal of the suggestion “in” enhanced for economic and social development to provide information system and equipment, and promote the ability of information industry development “and on September 28, 1995, the communist party of China 14 th central committee at the fifth plenary meeting bulletin” in “accelerate the HP c700 battery informationization of the national economy in progress” formulation. Then all of the program, the outline of the use of the frequency of information to the high.

The national informatization construction goal is: by 2000, initially forming a certain scale and relatively complete national informatization system; By 2010, will establish a sound, of significant scale, advanced national informatization system.

The national informatization system from the following six components, namely the information resources, the state believe interest rates, the application of information technology network, information technology and industry, information talent, information policy laws and regulations and standards.

Can see, our country’s information and foreign information highway and the national information infrastructure is different. Our country stressed information system between six elements close close department, will information resources development and utilization in the core status. In recent years, the development of it industry in China faster than the speed of growth in the national economy. During, the electronics industry years ago by 30%, the average telecom industry are increasing 40%. China communications network basically realized the digital and ChengKongHua. The national has initially build optical primarily, by digital microwave and satellite communication is complementary, DuoZhong means and network.

In recent years, China’s public data communications network construction speed quickly. Telecom department made a ChinaPAC built, ChinaDDN, ChinaNFRN digital communication network in China, forming the public data communications network.

By the network Internet technology constitute the network from the original cold war the United States defense department of internal test network that eight waiting eight to the U.S. education scientific research institutions I of the Internet, go after slow process. But since 1993 from stomach site since the invention, development browser home page to the present international Internet took only a few short years time, its current reached by the size and the speed of development is a bolt from the blue.

1993 years of Internet users in the hundreds of thousands of people, and only for according to the computer industry yearbook company in 1999 published reports, by the end of 1999 the global Internet users to more than 259 million. According to the company, estimates that by the end of 1999 the global Internet users the most of the 10 countries in order: the United States (110 million; ) , Japan [18 million; ) , British [14 million X HP 6735s battery 13.3 million; Canada ) , Germany , Australia .83 million , 6.8 million Brazil, China 6.3 million) “5.69 million, France, South Korea); (5.68 million). As the American report, it is estimated that by 2000 its users around the world, and more than 300 million when the nearly 100 million hosts and 230 million computers connected to the Internet? (In 2002, the Internet users rose to 490 million, 2006,. The United States has reached 920 million computer industry yearbook in 1999 the predicted results are simply contrasts, you can see the development of the Internet, on a explosion trend. This development momentum and the speed of development at present no see signs of slowing.

The vast information resources, convenient and quick way of communications and powerful multimedia work, can make more and Lenovo IdeaPad Y510 battery more people have already felt the Internet for the development of society, and the driving force great of the traditional concept of impact. It is because of the rapid development of the Internet, to force people to start thinking about a real information highway construction, broadband Internet to meet users to network communication channel bandwidth growing demand.

The Chinese are real manufacturing the ancestor of standardization. Qin shihuang terracotta warriors and horses in xian unearthed many weapons, through the study, the archaeological experts manufacturing process achieves the to the extent of the perfect. With the largest number of arrows, for example, almost every one of the size of the arrow is completely consistent, presents a modern air dynamics viewpoint is also in accordance with the curve is very perfect, flight furthest, and through the body strength is the largest. You know, this is two thousand DuoNian levels before.

1. The OSI seven layer model

OSI seven layer model also called OSI/RM, is the international organization for standardization of the definition of the network architecture model.

ISO in 1977 set up a special committee to needle points the network structure, this essay open systems interconnection model, and defines the function of each level. Open systems interconnection of the seven layers of the OSI reference model, including: Daniel things layer, the data link HP Pavilion DV6 battery layer, network layer, the transport layer, layer, layer and session said application layer.

The function of each layer for:

The physical layer. Provide for establish, maintain and broken in addition to physical link required mechanical, electrical, function and characteristics of the procedures, and provide on a link in the physical structure of the transmission and a flow, fault detection instructions function;

The data link layer. In the physical channel establish has certain information transmission grid type and transmission control function of the channel, provide the data link control the flow, detection and school are physical link produce error;

The network layer. Control of data through communication subnet activities, including routing choose choose, crowded control, network interconnection, and other functions, its characteristics of high is transparent, root according to the requirements of the transport layer to choose the quality of service, to the transport layer report fails to regain the mistake;

The transport layer. Provide establish, maintain and dismantle transfer the function of the connection, the choice of the network layer provides the most appropriate service, in the system provides the reliable between transparent data transmission, provides end-to-end error recovery and flow control;

Session layer. Provide between two processes to establish, maintain and the end of the session, providing interactive connection function of conversation, there are three management function of data flow direction control model, that is, all the way interaction of two road and two road and alternate conversation mode;

The presentation layer. Representative application process negotiations, said complete data transfer data, format and text compression;

The application layer. Provide OSI user service, such as transaction processing procedures, file transfer protocol and network management and so on.

Each network node with the seven levels of all or some level of function, each node of the same level of communication between the rules and conventions called protocols. A key component of the agreement is: grammar, including data format, code and signal electric equality; Semantic, including in coordination and error control information processing; Timing, including speed matching and sort.

OSI is the first network system, the standard about in this international standard, made clear the many of the concept of network, the development of the network has played a very important role in guiding the. The hierarchical analysis method, a method of classic in computer technology. But, OSI is not a standard of success:

The level division, caused too much of the relationship between the layer and layer is too complex. So far, no a network product to achieve all the seven layers of the content;

Standard itself to network interconnection of the definition of the development of the network speed, it is insufficient; plan

Lack of the relevant contents of network security, then in ISO7498-2 got complement, showed a lack of awareness of safety.

In essence, due to network interconnection OSI itself lack of understanding of the Internet to lost great opportunity of development, leading to be defeated by TCP/IP.

But, in the human network OSI development process in the historical contributions are indelible. 2. IEEE802 series

The main body of the Internet is actually the collection of local area network. The standard of local area network by beautiful kingdom is electrical and electronic engineers (ieee IEEE802 committee for, called IEEE802 standards. The 802 series standard in technology and market has been a huge success, then IEEE802 LAN standards MSI Wind U100 battery have been got ISO, the adoption of a computer LAN for the fact that, this is the standard ISO8802 standards.

IEEE802 basically include the following standards:

IEEE802.1, system structure and high-level interface;

IEEE802.2, logical link control LLC

IEEE802.3, CSMA/CD (with collision detection of the carrier with more complex protected reliably against detective road) access control method and the physical layer technical specifications;

IEEE802.4, token bus access control method and physical technical specifications;

IEEE802.5, token ring access control method and the physical layer standard;

IEEE802.6, access control method and the physical (technical standard;

IEEE802 standard mainly to solve the seven layers of the following two layer model. We can from another Angle to see IEEE802.

3. TCP/IP

The seven layers of the OSI model by influence, in order to TCP/IP protocol that system also has a corresponding five layer model.

In the TCP/IP protocol system, does not involve the content of the physical layer.

TCP and UDP is transport layer protocol. TCP mean TCP, UDP? Is the data reported agreement. According to professional term, TCP provide reliable transport layer does not provide the reliable service UDP transport services. Reliable and not how to distinguish the reliable?

This is like phone calls and emails through the post. When we through the telephone network is absorbing the voice communication, if interference, cause we can’t hear each other words, can immediately requirements to repeat. English “Pardon,” “Pardon please” or “commission on this money exchange” is used here; E-mail is different, if not to do special requirements, to the post office, we can’t guarantee letters were delivered accurately and letters of them received (of course can now be confirmed by phone or registered, and it became the TCP or UDP improved).

IP is network interconnection agreement, is the main network layer protocols. TCP and UDP data after group via IP network layer after the realization transmission.

ICMP is the control message agreement, subsidiary IP, IP layer through the ICMP and Lord machine or routers exchange control information, mainly is the message mistake and other information.

IGMP is Internet group management, its effect is Sony BPS2 battery a message agreement for the UDP data broadcast transmission to DuoGe host,.

ARP is address translation agreement, the role is to realize address analysis, from IP address to turn in MAC address (nic address); On the contrary, RARP from MAC address translation for IP address.

Note ARP and RARP agreement is we want to use every day of the agreement, this is because the popularity of Ethernet, basically most computer in the network is Ethernet. It is also said most of the ground floor of the TCP/IP is based on Ethernet.

Undoubtedly, the network crime since is a crime, it inevitably has the basic of crime

is harmful to the society; Criminal richtswitrig as soon as possible; Lu of the punishment of the criminal law should be protected by sex.

We want to bring a network behavior defined as crime, this kind of behavior must have the harmfulness of club will, and the illegal behavior in the law must have a clear definition, and the law must be clear and the behavior and shall be subject to punishment. This can give a definition:

“The network crime is to use computer and other network terminal, through the implementation of a certain social network danger of social behavior, this violate the provisions of relevant laws, and should be under certain punishment.” ‘

In December 2000 the through the National People’s Congress standing committee about maintenance decision of Internet security, the Chinese network crime involving the Internet into the safe operation of home, national security and social stability, socialist economic order and social management order PA3356U-3BRS battery and other crime four.

(!) Involving the Internet safety operation behavior

As soon as possible into the state affairs, national defense construction, advanced science and technology in the fields of computer

Information systems;

deliberately making, computer virus spread damaging programs, against the computer system and communication network, the computer system and communication network by damage;

without authorization in violation of state provisions, interrupt or communication service of computer network, made into the computer network or communication system will not work.

, 1, involving national security and social stability behavior and to use the Internet to all, libel or published, spread to other harmful information, to subvert the state power or overthrow the socialist system, or incite secession, break bad national unity;

And through the Internet to steal, disclose state secrets, intelligence or military secrets. And to use the Internet to stir up ethnic hatred, ethnic discrimination and undermining national unity; And use the Internet organization cult organizations, contact evil cults, breaking the national family members of the laws and administrative rules and regulations to implement.

In the social order of socialist market economy and social management order 夂 behavior

using the Internet or false and inferior product sales of goods, services for false propaganda;

using the Internet business reputation and hurt others goods Dell Studio 1537 battery reputation; And use the Internet to infringe upon intellectual property rights;

And to use the Internet to make up and spread affect securities, futures trading or other interference disorderly financial order of false information;

As soon as possible on the Internet, web pages, and establish pornographic web site links provide obscene service, or disseminates pornographic books, films, and audio and video, and pictures.

(3)) is concerned with personal, legal persons and other organizations of the person, property and the legal rights of behavior

9 to use the Internet to insult others or concoctive fact calumny others; And illegal intercepts, distort, delete others E-mail or other data material,

The infringement of citizens’ freedom and privacy; communication

And use the Internet to theft, fraud and extortion. to use the Internet to carry out other criminal actions other behavior is to point to as the development of the network might be of a certain harm sex behavior.

The communication medium can be divided into two categories: cable medium and wireless medium. Cable transmission medium is using of cable or optical fiber cable conductor transmission interface as the transmission quality, such as twisted pair, coaxial cable and optical fiber cable; Wireless transmission medium is using of electric wave or light transmission of media as a conductor, such as radio waves, microwave, and infrared and satellite communication, etc.

Transmission medium to the performance of the network has a bigger impact. Measure the PA3506U-1BAS battery transmission medium of the main technical performance indicators are: the transmission distance, transmission bandwidth, anti-interference ability, connecting method and price.

(a) twisted pair

Twisted pair is currently the most widely used medium Ethernet. The popularity of the twisted pair with the success of the hub and switches and realize. Telephone cable is twisted pair.

The basic principle of twisted pair is stick with insulating copper wires for the use of for a (stranding machine) according to certain specification intertwined with each other.

In a twisted pair speaking, when the outside electromagnetic signal in the two wires produce dry interference signals equal and opposite phase, jamming signal will offset each other.

Used in network of twisted pair, there are eight line, every two root twisted together.

Twisted pair has two kinds: the shielded twisted-pair cable and shielded twisted-pair cable. Shielded twisted-pair cables external package has a metal nets, used to shield the external interference. You put the phone with metal teacup cover up immediately, you can’t hear anything, it is this principle.

But the most popular are shielded twisted-pair cable, because the shielding twisted pair of the effect is not obvious, and the cost to high. Shielded twisted-pair cable at present general used only for industrial control field. About the standard of Ethernet have different versions, each version required cable specification and the transmission distance is different. Basically, use twisted-pair cable connection, dozens of meters to more than one hundred meters between the is reasonable.

(2) coaxial cable

Coaxial cables are the most widely cable TV network, but the computer network, the coaxial cable and network with the specification is not the same.

The interior of the coaxial cable has a copper-core as conductor, filled with middle of the insulation material layer is plastic, plastic layer is shielded network, and external as another wire, the cable from PVC or teflon material to cover the sheath.

At present more commonly used have two kinds of coaxial cable: a 50 cable, used for several words transmission, also known as “baseband coaxial cable”; Another for 75 cable, used to model the transmission, to is also referred to as a “broadband coaxial cable”.

Coaxial cable has very good anti-interference characteristics, the signal attenuation is less TOSHIBA A100 battery than twisted pair, can further distance transmission. In the etheric network have used two kind of coaxial cable, one kind is thick cable, and the other is the fine cable, thick cable is more good transmission characteristic.

Coaxial cable in the local area network applications with twisted pair and the popularity of the optical fiber has been eliminated.

(3) fiber

Optical fiber is the most promising transmission media outlets that almost all of the new network trunk are using optical fiber technology. Optical fiber to the desktop refers to use fiber instead of twisted pair computer connected to the Internet.

Optical fiber is in the form of a light pulse signal transmission, and the material is glass or plastic fiber d. Cable including fiber core, the packet level and protection to three.

Optical fiber can be divided into single-mode optical fiber and multimode fiber. Single-mode optical fiber provide only a light path, processing complex, but has the greater communication capacity and further to the transmission distance. Multimode fiber DuoTiao use light path through the same signal transmission, the refraction of light to control the transmission speed.

And cable, optical cable compared with many of the advantages:

Transmission communication capacity, can achieve very high transmission rate;

The light signal transmission loss of far smaller than the electrical signals, can further distance transmission, suitable for long distance transmission;

The light signal almost from external interference of electromagnetic signal, and has a strong resistance to ray electricity and anti-electromagnetism interference ability;

The light signal transmission in the fiber, almost nonexistent signal of the leak, good secrecy, information is not easy to be eavesdropping or intercept;

Fiber optic light weight, wiring easily;

The light signal transmission process is very low, ber transmission high reliability.

And cable, fiber optic cable connection at different ends Dell Inspiron E1505 battery of the need for electrical signals and light signal converter photoelectric conversion.

(4) wireless medium

Wireless media communication medium is a very important categories. Human beings use wireless as the communication medium of very long history, from the invention of the telegraph it started.

Wireless medium the biggest advantage is not to need to use a cable connection on both ends of the equipment, mobile flexible.

The first is WanNi watts’ bush (Vannevar bush). Roosevelt in 1940 WanNi tile, total all invited to join the bush U.S. defense research council and for chairman. WanNi watts’ bush on the Internet do the biggest contribution is to set up a small group, and the team eventually realize the NCP. He is the most direct to the Internet in the shadow is a paper for a dubbed “memex” information system of the revolution, his description of description to a lot of people into the early Internet research. WanNi tile “bush’s dream in the decades later today, with personal computers, web pages and search engines such as the development of technology and popularization, and ultimately become a reality.

The second key character is famous cybernetics founder norbert “wiener

(Norbert Wiener). Weiner’s cybernetics inspired a generation of scientists to PA3506U-1BRS battery think about how such as using computer as an extension of the human ability means. His theory is a direct impact on the Internet a few important period after the researchers.

The third key character is Marshall McLuhan Marshall (” some Herbert Marshall McLuhan points). Some Herbert Marshall McLuhan points first proposed a Global Village (Village) Global optimisation techniques the concept of a Global Village, and this is the so-called electronic nerve system interconnection (Interconnect) up. His point was a revolutionary, and thoroughly changed the people to the media, technology and communication understanding.

A very important meeting is 1956 years of Dartmouth artificial intelligence meeting

The 1956 Aritficial Intelligence (Dartmouth’t). In this time will be very clearly in discussion, put forward the “technology is to speed the concept of” development index, and put forward a series of which has led to the results. The meeting has not only led to the birth of the artificial intelligence can, and make later generations of scientists know that technology will be a kind of deep heart Ming the way benefit from humans.

This is the han fei zi “in the a fable, basically read primary school of the Chinese people will understand that.

a circle and information ecology

What is spear or hardened shields established? This is like that of a man, seem to be in a circle, a technical and safety of the vicious circle, as shown in figure 6-6 shows.

The development of computer technology, on the one hand, improve the security level of information on the Internet, on the other hand, we are basically have no way to prevent new technology is applied in the malicious behavior. Attack and defense, the conflict in a spiral line up in the process, to get development, but, this kind of development seems to have no to higher security. We With the Internet as a representative of the human information environment in a way, like the natural ecological system of the same.

The nature of the ecological system is refers to the biological community and its inorganic environment of the interaction Lenovo T410 battery of the natural systems, such as the forest ecological system, the Marine ecosystem, grassland ecological system, etc. Natural ecological system has the characteristics of typical: Ecological balance

The ecological balance is refers to the structure and function of the ecological system depend on each other in a certain time each part through the restriction, transformation, compensation, feedback, and show the energy and material of input and output to equal, material storage and needs relatively stable, information control system and transmission of smooth freely stable state.

In ecological equilibrium, ecological system has the following features:

“The dynamic balance

Ecological system of each component and its surroundings is constantly changing, sports, the balance of the ecosystem is a kind of dynamic balance.

And self adjust ability

When external interference, if this interference no more than a certain limits, ecological system itself through the self adjusting can go back to the original stable state.

relative balance

For ecological system in the human and the nature, any activities will be to affect it even destroy the balance, so the balance of the ecosystem is a relative balance.

Ecological system can be in three states:

growth state

Ecological system, the input of the early material than output, in a state of growth.

Nine stable state

Ecological system, the maturity of matter or energy input is equal to the output. ‘

imbalance state

Due to the influence of various factors of matter and energy input, output, productivity, and less than a balance is destroyed.

The ecological systemadjust itself

Due to external factors, if ecological system in a certain part of the change, and in allowing, within the bounds of the ecological system can now ego adjustment or repair itself in order to maintain the stability of the state. Ecological threshold is

Ecological system the self-adjustment ability is not an unlimited, must be in a certain conditions and range for, or ecological balance will be destroyed. This limit threshold is called the ecosystem. In a mature natural ecological system inside, biological birth, death, inorganic cycle changes as long as no more than ecological threshold is, its structure and function will not changed at all, this is typical of the natural ecological system.

Although, through long efforts, in the field of information security PA3284U-1BRS battery scientists invented all kinds of theory, methods and techniques, but did not bring us more security. We were faced with safety problem has become the norm of the information society, as natural born state system of ecological balance, as well as information security will also be a relative concept, the so-called security should be a relative balance. Facts prove that we might not have to do to get a law absolutely clean information environment.

Nature has high ecological system since the adjustment ability to achieve the ecological balance, also vowed to pursue a safety balance and not clean information ecological environment should be the goal of safety science believe interest rates, and we put the information environment called the information ecological environment.

(2) security’s future

In the I d technology area, never is all market decide. The rules of the game since 18\1 invention machine, 1 defines the 10 remember Moore’s law, was established after. Technology but are market tools.

Since the Internet architecture is sure, from the host, after the network to the Internet, each link of the inherent defect gradually revealed, but because many technology has the huge number of user groups and equipment, when many, the progress of technology instead become a long process. ‘

Internet security problems, especially so.

Engaged in security theory and technology research scientists and engineers have realized, make many security problems from the foundation of the network should solve, redefine the Internet the rules, but the problem is, very difficult. When a technology have a certain amount of the market and user after, it will inevitably become new technology block.

Again, what a scientist can ensure that new technology system can be without holes?

Spear and the shield law can occur at role.

With the development of the Internet, information security field research seems to give people a solemn and stirring feeling wave upon wave, but still can’t see completely resolved hope.

When security has become the norm of modern network society, to human being it like the some sorrow.

The Internet development up to now, are there and for the human services, and in the field, the network the researchers effort is not divided. On one hand, the safety problems in affect our the Internet use, on the other hand, also pushed the Internet technology, raise the level of all. But as discussed in the previous, the spiral of rising, and not for people with higher sense of security.

Looking to the future development of the Internet security problems, the solution Apple A1008 battery mainly has: # break has some network structure system, from the bottom of the realization of security. The Letter;

And in the existing system, the application of artificial intelligence theory and achievements, making the network

Form a intelligent system, deal with security.

Intelligent security is a new topic, also is the research focus in the field of information security. Make our network and computer has enough intelligence, it is human pursuit of the goal. The use of artificial intelligence method to solve the security problem, is an important way of network development in the future.

There’s one problem, the router to many network connectivity to constitute the Internet, when together received a group, it is how to know which one should be sent to the net? Collaterals

This is the router of work to do.

The current router basically has the following kinds of functions:

Network interconnection

This is the basic function of the router. The router LAN and provide various wide area network interface, some used for wireless will provide wireless connection.

Network management

Network management function also is the most important function of the router. The router configuration hp mini 210 battery management, provide including performance management, fault tolerant management and flow control, and other functions.

Function expansion

The router after long-term development, can provide some special services and security functions, such as packet filtering, packet forwarding, priority, reuse, encryption, and compression and the threshold, and so on.

The router internal have a of the crucial data structure: routing table. Routing process is the route table lookup process. In the routing table being the routing mediator necessary information.

There are two kinds of generating mechanism of routing table: static routing table and dynamic routing table, can also be called static routing and in dynamic routing.

By the system administrator ahead of the routing table set called static routing table. Static state routing tables are generally in the system when installation and configuration of the network is according to the predetermined. Static routing defect is not be with network topology structure changed.

Dynamic routing table is router according to certain algorithm and generating strategy, according to the operation condition of network system and automatic adjustment route table. According to the routing protocol router the function of the network, provide to the situation of the automatic identification, automatic calculation of data transmission is the most beautiful path.

A router is located in the network layer, network layer provides equipment in PA3284U-1BAS battery connection services. By the way the connecting with network can use in data link layer and the physical layer completely different association appropriately. According to different realization mechanism, the router can transfer fee, according to transfer time delay, network congestion or source and the distance between the end to choose the best path.