Visual Network Enlightenment. Book review for web designer
Information for consideration CSS Zen Garden is a site that was born on May 8, 2003. The site consists of a single HTML file, by the example of which it…

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The main elements of the modern site.
Elements of a modern web site. So from the first estimate, it is certainly difficult to identify the main features of a modern web site. But I still try to…

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What is in the name?

When you use the web or send e’mail, you use the domain name to do this. For example, the Uniform Resource Locator or URL “http://www.kavkazchat.com” contains the domain name kavkazchat.com, as well as, for example, e’mail address admin@kavkazchat.com. Every time you use a domain name, you use the DNS server of the Internet to translate the easily readable domain name into a computer-readable IP address. Top-level domain names, also called first-level names, include such as .COM, .ORG, .NET, .EDU, .GOV, etc. Each top-level domain contains a huge list of second-level domains, for example, a first-level domain .COM includes:
kavkazchat
hotmail
microsoft
The DNS server accepts requests from programs or from other DNS servers in order to translate the domain name into an IP address. When a DNS server receives a query, it can do the following:
He can respond by issuing an IP address if he already knows the IP address of the requested domain name.
He can contact another DNS server and try to find out the IP address of the requested domain name from him. Perhaps he will do this many times.
He can answer “I have no idea about the IP address of the requested domain, but here is the IP address of the DNS server that may know more than me.”
It may return an error message because such a domain name does not exist or the name was specified incorrectly.
Suppose you have written the URL http://www.kavkazchat.com in your browser. The browser sends a request to the DNS server. After receiving the request, the DNS server will start searching and contact one of the main DNS servers. The main (root) DNS servers know the IP addresses of all DNS servers that are responsible for top-level domains. The DNS server will request data from www.kavkazchat.com from the root servers, and the root server will respond, “I do not know the IP address of www.kavkazchat.com, but this is the IP address of the DNS server that is responsible for the .COM domain zone.”
After that, the DNS server sends a request to the DNS server responsible for .COM domains, and will receive a response like this: “I do not know the IP address of www.kavkazchat.com, but this is the IP address of the DNS server responsible for the domain kavkazchat.com”. After that, your DNS server will connect to our DNS server (ns1.kavkazchat.com) and receive from it, finally :), the IP address (66.28.63.241) of the information resource www.kavkazchat.com, after that, it will return the IP address to your browser .
One of the key points in the work of the Internet is reliability. Therefore, there are many DNS servers of different levels, so if one fails, that is, spare ones in order to give answers to incoming requests. After the DNS server receives a response to its request, but caches (saves) the resulting IP address. Thus, once having received the IP address of the server responsible for the .COM zone from the root server, it will not have to contact the root server again (for some time) to obtain this information. DNS servers can cache every request (by the way, they can not cache at all), caching helps prevent linking and speeds up the entire process of resolving domain names to their corresponding IP addresses.
Although this whole process is completely invisible to the average user, DNS servers daily process billions of queries and are an integral part of the Internet. The fact that this database, which is spread all over the world, works so clearly and imperceptibly day after day attests to a good scheme of the underlying DNS servers.
Web Server.
The existence of the Internet would be impossible without Internet servers. All machines on the Internet are either clients or servers. Computers that provide services (such as mail, web, etc.) for other computers are called servers. The machines that are used to connect and use these services are called clients. There are Web servers (Web servers), mail servers (e’mail servers), FTP servers (FTP servers, for file sharing) and many others for other needs and needs of the Internet.
When you connect to the site www.kavkazchat.com to open the main page of the website, you are the user sitting at the client computer that connects to the web server that serves our website. The web server finds the page you requested and sends it to you. Client computers accessing the server do it in a special way and send their request to a specific program running on the server. For example, if you run a web browser on your computer, it will access the web server, not the mail server, etc.
As a rule, the server has a static (permanent) IP address, which, if changed, is very rare. The home computer that uses the phone and modem to connect, as a rule, automatically receives a new IP address after each new connection with the provider. The resulting IP address is unique and may become different after the next connection.

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