How Domain Name Server (DNS) works

Having some trouble with your Domain? Want to know how it all works? These discussions will answer all your questions about Domains and the issues surrounding them, including legal, buying and squatting solutions.
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real
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Posts: 7
Joined: Mon Feb 17, 2014 1:40 pm

Tue Sep 26, 2017 11:10 am

The DNS (Domain Name Server) system is a crucial system for running the internet, which however is a mystery unknown to many. Without DNS`s would not work the domain names that we use every day, really that way would not work any, but why. 

Each computer connected to any network, particularly the Internet has a unique "logical" address, something like a telephone number, which we call IP address, IP addresses currently used (version 4) consists of four sections numeric separated by a dot, a typical IP address would look like this: 101.100.134.79 this is just an example.

Since it is very difficult to memorize hundreds of numerical addresses (as many pages as we visit daily), for that we created the network system that we now know as the internet or more appropriately as World Wide Web invented a method of "translating" these numerical addresses to textual directions. For some reason, which is subject matter of another type of article, humans are much easier to learn names and words than numerical sequences, therefore made the appearance of domain names. On the internet we know today people know how to access www.google.com but not to 172.217.13.78 which is one of the IP addresses used by Google. 

Why do the changes take place on the server?

Another very common situation is that when we change the address of a domain from one DNS server to another, our provider tells us that the "propagation" can take 24 to 72 hours (usually much less). What does this mean? 

What happens is that in order not to overload the internet root servers and reduce traffic by querying DNS "translations" of domain names to IP addresses, the DNS system works in such a way that temporary records of certain popular translations are stored, for example: if you make a query to search www.nethostingtalk.com , the DNS system of our internet access provider will return the IP resulting from that query.

In order to do this translation we probably had to consult directly to an internet root server, however, if we re-search for that address (or someone in the same network or "neighborhood" searches for it) is temporarily stored on a DNS server of our internet access provider, which saves you having to go to search for that translation directly to the internet root servers.


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hmsnaveen95
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Joined: Thu Jun 07, 2018 4:44 pm
Location: Chennai, india

Mon Jun 11, 2018 4:29 pm

The first step is to register your domain name. To put it simply, you buy it so that you are the one who will be able to make the association name <-> address. Once you are the proud owner of the domain name, you have access to what is called the "DNS zone", which is basically a list of pairs name <-> IP. It's a list because when you own a domain name, you can also use sub-domains (mail.google.com, plus.google.com, ...), each of them can be associated with a different address. Once you have configured the DNS zone, it is stored on your registrar's server.

What is left to explain is how the queries are made. How does your computer know the IP address for a given name? When you type www.google.com in your browser, the browser starts by asking the translation to a root nameserver. There are 13 of them, and they are the entry points of the DNS protocol.

When they receive a request, they usually don't know the answer (as there are too many domain names) but they know who to ask. For example, they know that www.google.com depends on the "com" DNS server (which handles the domain names with the .com TLD). So the request is then sent to this server, which will in its turn know who to ask, and this continues until the request is sent to your registrar's server, which will know the answer your computer is looking for.

Now, in reality, this is not the real process. As you can imagine, the number of requests is overwhelmingly huge, and the 13 servers would create a bottleneck a lot too small for every request. There are complex caching systems used to relieve the pressure on these servers and they are, in fact, involved in only a small part of the traffic.

Caching DNS servers will store the answer to DNS queries for a given time, and answer directly if the same query arrives again in this time frame. In practice, your computer will ask these caching servers, and the caching server will ask the authoritative servers for the answer (if it's not in the cache).
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