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Image: Statista. License and Republishing. For example, a typical IP address might be This was fine when there were only a few hosts out there, but it became unwieldy as more and more systems came online.
The first solution to the problem was a simple text file maintained by the Network Information Center that mapped names to IP addresses. Soon this text file became so large it was too cumbersome to manage. Uniform Resource Locators When you use the Web or send an e-mail message, you use a domain name to do it.
So does this e-mail address: example howstuffworks. Every time you use a domain name, you use the Internet's DNS servers to translate the human-readable domain name into the machine-readable IP address.
Top-level domain names, also called first-level domain names, include. EDU and. Within every top-level domain there is a huge list of second-level domains. For example, in the. COM top-level domain must be unique.
The left-most word, like www, is the host name. It specifies the name of a specific machine with a specific IP address in a domain. A given domain can, potentially, contain millions of host names as long as they are all unique within that domain. DNS servers accept requests from programs and other name servers to convert domain names into IP addresses. When a request comes in, the DNS server can do one of four things with it: It can answer the request with an IP address because it already knows the IP address for the requested domain.
It may have to do this multiple times. ORG, etc. Your DNS server would ask the root for www. One of the keys to making this work is redundancy.
There are multiple DNS servers at every level, so that if one fails, there are others to handle the requests. The other key is caching. Once it has made a request to a root DNS server for any.
DNS servers can do this for every request, and this caching helps to keep things from bogging down. Even though it is totally invisible, DNS servers handle billions of requests every day and they are essential to the Internet's smooth functioning. The fact that this distributed database works so well and so invisibly day in and day out is a testimony to the design.
Clients and Servers Internet servers make the Internet possible. All of the machines on the Internet are either servers or clients. The machines that provide services to other machines are servers. And the machines that are used to connect to those services are clients. There are Web servers, e-mail servers, FTP servers and so on serving the needs of Internet users all over the world. You are accessing the HowStuffWorks Web server. The server machine finds the page you requested and sends it to you.
Clients that come to a server machine do so with a specific intent, so clients direct their requests to a specific software server running on the server machine. For example, if you are running a Web browser on your machine, it will want to talk to the Web server on the server machine, not the e-mail server. A server has a static IP address that does not change very often. A home machine that is dialing up through a modem, on the other hand, typically has an IP address assigned by the ISP every time you dial in.
That IP address is unique for your session -- it may be different the next time you dial in. But that was enough to support a vibrant online community. A new bulletin board system called Usenet was invented in and caught on quickly. Usenet was organized by topic, allowing users to swap programming tips, recipes, jokes, opinions about science fiction, and much more. But network operators realized that a centralized network would eventually become unmanageable if it continued to grow.
They decided that the network should be reorganized as a decentralized "network of networks. These standards specified the basic format of data packets transmitted across the internet. But the new standard paved the way for much faster network growth by lowering the barrier to entry for new networks. One of the first new networks to connect to the new internet was CSNET, which was funded by the National Science Foundation to link computer science departments across the country.
Today, the internet is made up of more than 40, different networks. During the s, the National Science Network funded several supercomputing centers around the United States. The primary goal was to allow computer science researchers to log into the supercomputers and perform academic research. As a result, the NSFNET became the internet's "backbone," the high-speed, long-distance network that allowed different parts of the internet to communicate.
That meant that students and faculty at a growing number of universities had access to email, Usenet, and even a recently-invented application called the World Wide Web.
And although the NSFNET was officially restricted to non-commercial use, for-profit companies were increasingly connecting to the network as well, setting the stage for the commercialization of the internet that followed.
In , the internet was still dominated by the United States but it was becoming a truly global network. This is a map of information flow on Usenet, an bulletin board application that allowed users to swap recipes, jokes, programming tips, and more. In , the Clinton Administration privatized the internet backbone. Commercial firms took over the job of carrying long-distance internet traffic, allowing the government-funded NSFNET to be decommissioned.
Officials were careful to ensure that no single company controlled too much of the backbone, helping to create a competitive market for internet connectivity that still exists today. These four maps illustrate how the market had evolved by the turn of the century. Each had its own nationwide and global network, and they competed with each other to provide long-distance connectivity to smaller networks.
By , almost half of Americans were on the internet, but ordinary people in most other countries had not yet joined the network. There were fewer than million internet users worldwide. Since then, the internet has gone from an American network to a truly global one. This map illustrates how the internet came first to wealthy countries, then to middle-income countries, and finally to poor countries.
Today, there are more than 2. Jeff Ogden. There are two basic ways people can log onto the internet: through a fixed broadband connection at home or in an office and via a wireless connection on a cell phone or tablet. This data from the International Telecommunications Union shows how popular fixed internet access is around the world.
It shows internet access is widespread in most parts of the world, but is still fairly scarce in much of sub-Saharan Africa and the Middle East. Fixed internet access allows multiple devices in a customer's home to access the internet. Fixed connections are also ideal for streaming-video services such as Netflix because they tend to have greater capacity than wireless networks.
This map shows the percentage of consumers around the world who have mobile internet access note that the colors on this map are not directly comparable to the previous map.
In the developed world, people usually got fixed internet access first and obtained mobile internet devices later. But some developing countries are skipping the construction of fixed broadband networks altogether.
This is cost-effective because a single cell phone tower can provide service to hundreds of customers. For examle, 2. Mobile internet access can have profound implications for people in isolated areas. Farmers can use mobile phones to learn about recent market developments, increasing the amount they can get for their crops.
Some mobile phone operators also offer sophisticated payment capabilities, allowing people who don't have access to the conventional banking system to make electronic payments.
A few wealthy countries, including Japan, South Korea, and Sweden, that have more mobile internet subscriptions than people. Some customers have two more or smartphones, tablets, or other connected mobile devices. Internet access is a lot faster in some places than others. According to Speedtest.
The United States clocks in at number 30, with average speeds of 24 Mbps. These figures are worth taking with a grain of salt because they're based on a self-selected sample. Users must visit the speedtest. Still, the data permits interesting cross-country comparisons. For the internet to work, everyone needs a unique Internet Protocol IP address.
To coordinate the distribution of these addresses, the internet is broken up into five zones. Each zone has been assigned hundreds of millions of IP addresses to manage. Unfortunately, the original internet architecture, called IPv4, only allows for about 4 billion addresses, and the network has nearly exhausted the supply. The problem is particularly growing in fast-growing regions like Asia. Engineers have developed a long-run solution to this problem: switching to a new internet standard called IPv6.
IPv6 offers such a large number of potential addresses that the world will never run out. But adoption of IPv6 has been slow. Today, the overwhelming majority of internet traffic uses the old standard. But with few IPv4 addresses left, people joining the internet in the future will have little choice but to use IPv6.
IP addresses have a numeric format like this: But it's easier for people to remember domain names such as vox. The domain name system DNS acts like a directory system, telling computers wanting to view a website like www. The system is hierarchical: the. Domains like. But other countries are more likely to use what's known as country-code top level domains ccTLD. Every country in the world has a ccTLD. This map shows the ccTLDs in Europe. Even very small countries get ccTLDs.
Here's a close-up of the area around Australia and the many small island nations that have their own domain names. Some of these countries realized that they could make a lot of money if they opened their domains to foreigners.
The result: popular websites like last. Today the fastest way to transmit information over long distances is with fiber optics — long, thin strands of glass that carry information as pulses of light. Because a single fiber can transmit as much as billion bits per second Gbps, about ten thousand times faster than a typical home broadband connection and a cable can contain hundreds of fibers, a single cable can have enough capacity for the communications of millions of users.
All that data has proven irresistible to the National Security Agency, which has developed a variety of techniques to scoop up data as it flows through fiber optic cables. Fiber optic cables are relatively fragile. In , two fiber optic cables that connect Middle Eastern countries to India were cut, leading to disruptions for many internet users in Egypt and India.
Some press reports suggested that the damage was caused by a ship's anchor being dragged along the bottom of the Mediterranean, but the Egyptian authorities have said no ships were in the area at the time the cables were damaged. The exact cause of the outage remains a mystery. Sometimes internet access is disrupted due to accidents.
In other cases, it's deliberate government policy. For example, during the Tahrir Square protests, the Egyptian government cut off Egypt's connections to the rest of the internet. This was possible because Egypt's links to the outside world were controlled by a handful of large companies.
This map shows which countries have few enough links to the outside world to be at risk of this kind of censorship.
Some countries, such as the United States, have dozens of links to the outside world, making a coordinated shutdown of the US internet almost impossible.
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