计算机网络外文翻译.docx

附 录一、英文原文：the networksbirth of the netthe internet has had a relatively brief, but explosive history so far. it grew out of an experiment begun in the 1960s by the u.s. department of defense. the dod wanted to create a computer network that would continue to function in the event of a disaster, such as a nuclear war. if part of the network were damaged or destroyed, the rest of the system still had to work. that network was arpanet, which linked u.s. scientific and academic researchers. it was the forerunner of todays internet. in 1985, the national science foundation (nsf) created nsfnet, a series of networks for research and education communication. based on arpanet protocols, the nsfnet created a national backbone service, provided free to any u.s. research and educational institution. at the same time, regional networks were created to link individual institutions with the national backbone service. nsfnet grew rapidly as people discovered its potential, and as new software applications were created to make access easier. corporations such as sprint and mci began to build their own networks, which they linked to nsfnet. as commercial firms and other regional network providers have taken over the operation of the major internet arteries, nsf has withdrawn from the backbone business. nsf also coordinated a service called internic, which registered all addresses on the internet so that data could be routed to the right system. this service has now been taken over by network solutions, inc., in cooperation with nsf. how the web worksthe world wide web, the graphical portion of the internet, is the most popular part of the internet by far. once you spend time on the web,you will begin to feel like there is no limit to what you can discover. the web allows rich and diverse communication by displaying text, graphics, animation, photos, sound and video. so just what is this miraculous creation? the web physically consists of your personal computer, web browser software, a connection to an internet service provider, computers called servers that host digital data and routers and switches to direct the flow of information. the web is known as a client-server system. your computer is the client; the remote computers that store electronic files are the servers. heres how it works: lets say you want to pay a visit to the the louvre museum website. first you enter the address or url of the website in your web browser (more about this shortly). then your browser requests the web page from the web server that hosts the louvres site. the louvres server sends the data over the internet to your computer. your web browser interprets the data, displaying it on your computer screen. the louvres website also has links to the sites of other museums, such as the vatican museum. when you click your mouse on a link, you access the web server for the vatican museum. the glue that holds the web together is called hypertext and hyperlinks. this feature allow electronic files on the web to be linked so you can easily jump between them. on the web, you navigate through pages of information based on what interests you at that particular moment, commonly known as browsing or surfing the net. to access the web you need web browser software, such as netscape navigator or microsoft internet explorer. how does your web browser distinguish between web pages and other files on the internet? web pages are written in a computer language called hypertext markup language or html.some web historythe world wide web (www) was originally developed in 1990 at cern, the european laboratory for particle physics. it is now managed by the world wide web consortium, also known as the world wide web initiative. the www consortium is funded by a large number of corporate members, including at&t, adobe systems, inc., microsoft corporation and sun microsystems, inc. its purpose is to promote the growth of the web by developing technical specifications and reference software that will be freely available to everyone. the consortium is run by mit with inria (the french national institute for research in computer science) acting as european host, in collaboration with cern. the national center for supercomputing applications (ncsa) at the university of illinois at urbana-champaign, was instrumental in the development of early graphical software utilizing the world wide web features created by cern. ncsa focuses on improving the productivity of researchers by providing software for scientific modeling, analysis, and visualization. the world wide web was an obvious way to fulfill that mission. ncsa mosaic, one of the earliest web browsers, was distributed free to the public. it led directly to the phenomenal growth of the world wide web.understanding web addresses you can think of the world wide web as a network of electronic files stored on computers all around the world. hypertext links these resources together. uniform resource locators or urls are the addresses used to locate these files. the information contained in a url gives you the ability to jump from one web page to another with just a click of your mouse. when you type a url into your browser or click on a hypertext link, your browser is sending a request to a remote computer to download a file. what does a typical url look like? here are some examples:/the home page for study english. /pub/ a directory of files at mit* available for downloading. news:rec.gardens.roses a newsgroup on rose gardening. the first part of a url (before the two slashes* tells you the type of resource or method of access at that address. for example: http - a hypertext document or directory gopher - a gopher document or menu ftp - a file available for downloading or a directory of such files news - a newsgroup telnet - a computer system that you can log into over the internet wais* - a database or document in a wide area information search database file - a file located on a local drive (your hard drive) the second part is typically the address of the computer where the data or service is located. additional parts may specify the names of files, the port to connect to, or the text to search for in a database. you can enter the url of a site by typing it into the location bar of your web browser, just under the toolbar. most browsers record urls that you want to use again, by adding them to a special menu. in netscape navigator, its called bookmarks. in microsoft explorer, its called favorites. once you add a url to your list, you can return to that web page simply by clicking on the name in your list, instead of retyping the entire url. most of the urls you will be using start with http which stands for hypertext transfer protocol*. http is the method by which html files are transferred over the web. here are some other important things to know about urls:a url usually has no spaces. a url always uses forward slashes (/). if you enter a url incorrectly, your browser will not be able to locate the site or resource you want. should you get an error message or the wrong site, make sure you typed the address correctly. you can find the url behind any link by passing your mouse cursor over the link. the pointer will turn into a hand and the url will appear in the browsers status bar, usually located at the bottom of your screen.domain nameswhen you think of the internet, you probably think of .com. just what do those three letters at the end of a world wide web address mean? every computer that hosts data on the internet has a unique numerical address. for example, the numerical address for the white house is 00. but since few people want to remember long strings of numbers, the domain name system (dns)* was developed. dns, a critical part of the internets technical infrastructure*, correlates* a numerical address to a word. to access the white house website, you could type its number into the address box of your web browser. but most people prefer to use . in this case, the domain name is . in general, the three-letter domain name suffix* is known as a generic top-level domain and describes the type of organization. in the last few years, the lines have somewhat blurred* between these categories. .com - business (commercial) .edu - educational .org - non-profit .mil - military .net - network provider .gov - government a domain name always has two or more parts separated by dots and typically consists of some form of an organizations name and the three-letter suffix. for example, the domain name for ibm is ; the united nations is . if a domain name is available, and provided it does not infringe* on an existing trademark, anyone can register the name for $35 a year through network solutions, inc., which is authorized to register .com, .net and .org domains. you can use the box below to see if a name is a available. dont be surprised if the .com name you want is already taken, however. of the over 8 million domain names, 85% are .com domains. icann, the internet corporation for assigned names and numbers, manages the domain name system. as of this writing, there are plans to add additional top-level domains, such as .web and .store. when that will actually happen is anybodys guess. to check for, or register a domain name, type it into the search box.it should take this form: in addition to the generic top-level domains, 244 national top-level domains were established for countries and territories*, for example: .au - australia .ca - canada .fr - france .de - germany .uk - united kingdom for us $275 per name, you can also register an international domain name with net names. be aware that some countries have restrictions for registering names. if you plan to register your own domain name, whether its a .com or not, keep these tips in mind: the shorter the name, the better. (but it should reflect your family name, interest or business.) the name should be easy to remember. it should be easy to type without making mistakes. remember, the internet is global. ideally, a domain name will read in a language other than english.decoding error messagesas you surf the net, you will undoubtedly find that at times you cant access certain websites. why, you make wonder? error messages attempt to explain the reason. unfortunately, these cryptic* messages baffle* most people. weve deciphered* the most common ones you may encounter.400 - bad request problem: theres something wrong with the address you entered. you may not be authorized* to access the web page, or maybe it no longer exists. solution: check the address carefully, especially if the address is long. make sure that the slashes are correct (they should be forward slashes) and that all the names are properly spelled. web addresses are case sensitive, so check that the names are capitalized in your entry as they are in the original reference to the website. 401 - unauthorized problem: you cant access a website, because youre not on the guest list, your password is invalid or you have entered your password incorrectly. solution: if you think you have authorization, try typing your password again. remember that passwords are case sensitive. 403 - forbidden problem: essentially the same as a 401. solution: try entering your password again or move on to another site. 404 - not found problem: either the web page no longer exists on the server or it is nowhere to be found. solution: check the address carefully and try entering it again. you might also see if the site has a search engine and if so, use it to hunt for the document. (its not uncommon for pages to change their addresses when a website is redesigned.) to get to the home page of the site, delete everything after the domain name and hit the enter or return key. 503 - service unavailable problem: your internet service provider (isp) or your companys internet connection may be down. solution: take a stretch, wait a few minutes and try again. if you still have no luck, phone your isp or system administrator. bad file request problem: your web browser may not be able to decipher the online form you want to access. there may also be a technical error in the form. solution: consider sending a message to the sites webmaster, providing any technical information you can, such as the browser and version you use. connection refused by host problem: you dont have permission to access the page or your password is incorrect. solution: try typing your password again if you think you should have access.failed dns lookup problem: dns stands for the domain name system, which is the system that looks up the name of a website, finds a corresponding number (similar to a phone number), then directs your request to the appropriate web server on the internet. when the lookup fails, the host server cant be located. solution: try clicking on the reload or refresh button on your browser toolbar. if this doesnt work, check the address and enter it again. if all else fails, try again later. file contains no data problem: the site has no web pages on it. solution: check the address and enter it again. if you get the same error message, try again later. host unavailable problem: the web server is down. solution: try clicking on the reload or refresh button. if this doesnt work, try again later. host unknown problem: the web server is down, the site may have moved, or youve been disconnected from the net. solution: try clicking on the reload or refresh button and check to see that you are still online. if this fails, try using a search engine to find the site. it may have a new address. network connection refused by the server problem: the web server is busy. solution: try again in a while. unable to locate host problem: the web server is down or youve been disconnected from the net. solution: try clicking on the reload or refresh button and check to see that you are still online. unable to locate server problem: the web server is out-of-business or you may have entered the address incorrectly. solution: check the address and try typing it again. 二、英文翻译：网 络网络的诞生迄今为止，因特网的历史虽比较简短，但仍然是突破性的。在1960年代，因特网是在美国国防部的实验中产生的。dod希望发明一种计算机网络，它能在类似原子核战争的重大灾难中发挥作用。如果网络的一部分遭到损害，或者是毁灭性的破坏，那么系统的其它部分仍能正常工作。那个网络就是阿帕网，它连接到美国的科学和学术研究人员。阿帕网是我们今天所用网络是始祖。在1985年，全美科学基金会（全美科学财团）创建了nsfnet，这是一系列用于研究和教育交流用的网络。根据阿帕网议定书，nsfnet创建了国家支柱服务，即对任何美国研究是学术机构提供免费服务。同时，地区网络把私人机构和国家主干服务连接起来。正如人们对其潜力的估计，也正由于使用起来更简单的新的软件的问世，nsfnet迅速地成长起来。类似美国sprint通讯公司和美国著名的mci公司的一些公司也开始构筑他们自己的网络，这些网络连接到nsfnet上。当商业公司是其它的地区网络提供商承担起主要网络动脉的管理是，nsf（全美科学财团）已经从主干商务中退了下来。nsf也同一种叫做internic的服务对等，internic登记因特网上的所有的地址，以便数据能传送到正确的系统中。现在这项服务已由网络sloution公司是全美科学财团合力承担了。网络是如何工作的世界万维网因特网的一部分是迄今为止因特网中最流行的部分。只要你肯花时间浏览网页，你将会发现网上没有你找不到的东西！网页通过展示文字，图画，动画，照片，声音和录象来使得通讯丰富多采。那么什么是这奇迹般的创造呢？网络实际上包括你的个人电脑，网络浏览器软件，与internet服务商的连接，被称为主数字数据和路由器，以及引导信息流的开关。万维网已客户机系统著称。你的计算机是客户；储备电子文件的远程计算机是服务器。以下就是它的工作方式：假设你要访问louver博物馆的网点。首先在你的网络浏览器中输入这个网点的url地址（等下还会有更多关于这的探讨）。然后你的浏览器象主管louver的网络服务器请求网页。louvre的服务器通过因特网向你的计算机发送数据。你的网络浏览器翻译这些数据并把它们显示在屏幕上。louvre网点也有其它博物馆的站点的连接。当你在链接上单击鼠标时，你从网络服务器中取得焚蒂冈的博物馆的网页。使得万维网联系在一起的“粘合剂”是超文本和超链接。这个特征允许网上的电子文件被链接因此你可以很容易的跳过它们。在网上，你可以选择你当时所感兴趣的页面来看，这通常被叫做浏览或者冲浪。为了能上网浏览，你需要安装网络浏览器的软件，例如网景或者微软公司的internet explorer浏览器。那么你的网络浏览器是如何区分网上的web页面和其它的文件的呢？网页是由超文本传输语言或html语言等计算机语言写成的。一些网络的历史万维网（www）在1990年在cern粒子物理的欧洲实验室被开发。它现在由万维网国际财团管理，万维网财团也是著名的万维网机构。万维网国际财团向许多包括美国电话电报公司，阿道比系统公司，微软公司和sun microsystems公司在内的公司的社团的成员提供资金。其目的在于通过发展技术规格和对每个人都免费的参考软件来促进网络的发展。国际财团由麻省理工学院和inria（法国国家为计算机科学的研究学会）运作，inria作为欧洲的主人，与cern保持合作关系。在厄巴纳-尚佩恩的伊利诺斯大学的国际超高速计算应用中心（ncsa），在早期的物理软件运用到由cern创建的万维网的发展中起到了一定作用。ncsa智力于通过提供给研究人员用于模拟，分析，和想象的软件来提高他们的生产率。明显的万维网就是完成那个使命的方法！ncsa mosaic最初期的网络浏览器之一，已被广泛使用。是它导致了万维网的非凡的成长！网 址world wide web可以被理解为存储在全世界计算机上的网络电子文件。超级链接将这些资源连接在一起。统一资源标示符或者urls是定位这些文件的地址。包含在一个url里的地址信息可以使你轻轻一点便从一个网页跳到其他页面上。当你在浏览器上键入url地址或者点击超级链接，你的浏览器会立刻发一个请求到远端的主机去下载文件。传统的url是什么样的呢？这有几个例子：/这是张英文学习的首页。/pub/mit学院主页下的一个文件下载路径news:rec.gardens.roses一个关于玫瑰园艺的新闻组一个url的第一部分（双斜杠之前的部份）为资源的类型或者这个地址的存取方法。例如：http- 表示一个超文本文档或路径gopher- 表示一个gopher文档或菜单ftp- 表示一个可以下载的文件或一个这种文件的路径news- 表示一个新闻组telnet- 表示一个通过internet登陆的计算机系统wais-表示一个广域信息搜索数据库的数据库或文档file- 表示一个存储在本地硬盘上的文件（你的硬盘）第二部分是放置数据或服务的一个典型计算机地址。其他部分可以为具体的文件名，连接的端口号，或者需要在数据库中查寻的文本。你可以在网页浏览器的工具栏下的定位条里键入一个站点的url。大多数的浏览器通过把你访问过的urls添加到一个特殊的菜单里将其记录下来，以便以后再次使用。再netcape的navigator中，它叫书签。在microsoft explorer中，则叫做favorites。一旦你添加一个url到列表中，你可以通过简单的点击列表里的名字返回那个网页，而不用在此间如完全的url.你使用的大多数的urls为http开头代表hypertext transfer protocol。http是一种将html转换为网页的方法。这有一些关于使用urls应该注意的地方： 一个url通常不包括空格。一个 url通常要到用双斜杠。如果你输入的url不正确的，你的浏览器将不能找到你想要的站点或资源。你将会收到一个错误的信息或访问一个错误的网页，所以确保你键入地址的正确性。当你将鼠标的光标放到一个链接上，在这个链接的url将显现出来。鼠标的指针将变为手状而且url将出现在浏览器屏幕的底端的状态条里。域 名当你想到internet,你可能会想到“.com”。这个www网址的最后三个字母到底实是什么意思呢？在internet的主机数据上，每个主机有一个独特的数字地址。例如，代表白宫的地址是00。因为很少人想去记那么一长串数字，所以域名系统被开发出来。dns，作为一项internet核心技术架构的一部分，将一个数字地址关联为一个词。要访问白宫的网站，你当然可以敲入那一串数字在地址栏里，但大多数人更愿意使用来代替它。在这个例子中，域名为。通常，三个字母的后缀域名被作为通用顶级域名用来描述一个组织类型。在过去的几年中这