They often use the analogy to explain the domain name system is that it serves as the phone book for
the Internet by translating human friendly computer host names into IP addresses.
Simply, DNS is a directory of names that match with IP addresses.
As you may know, each device connected to the Internet as a unique IP address with other machines used
to find the device.
DNS servers eliminate the need for humans to memorize IP addresses such as two one two eight zero seven
five one three four.
Think about the websites you visit every day, Google and YouTube, Facebook, Twitter, etc., without
DNS, we would have to reach these sites by using their IP addresses instead of their names.
I think remembering the names is so much easier than remembering the strange numbers, but it's still
possible to reach the computer with that strange number of string as well.
Now, DNS deserves to have far more time spent on it.
It could be a whole course in and of itself, but I just want to explain it simply without going to
deep.
So when you enter the you are L, such as dub, dub, dub, dot, Google dot com into the Web browser,
the request is not directly sent to the Google servers.
Instead, the request goes to the DNA that uses a lookup table to determine the IP address of the website
that is being requested.
Then it forwards this information to the proper servers and returns the information requested to your
specific browser.
DNS server is a computer server which contains a database of public IP addresses and their associated
host names, it translates those common names to IP addresses as requested.
DNS servers run special software and communicate with each other using special protocols.
DNS is a client server network communication system.
DNS clients send their requests to and receive the responses from DNS servers.
The request containing the name and resulting in an IP address being returned from the server are called
forward DNS lookups.
The request containing IP addresses and resulting in the names are called the reverse DNS lookups.
The DNS directorate that matches name to number isn't located all in one place.
Pretty much like the Internet itself, the directory is distributed around the world, stored on domain
name servers that all communicate with each other on a very regular basis to provide updates as well
as redundancies.
With more than 332 million domain names listed by the end of 2017, a single directory would be very
large indeed.
So when you type mailed out Google dot com into your browser, your browser sends a query over the Internet
to find a Web site.
It's a query seeking to match the domain name with its corresponding IP address.
So let's follow the path of this question over the Internet infrastructure.
The first server your query interacts with is the DNS resolver, which can be operated by your ISP Internet
service provider, a resolver is basically responsible for initiating and sequencing the queries that
ultimately lead to a full resolution.
Domain name resolvers determine the domain name servers responsible for the domain name in question
by a sequence of queries, starting with the rightmost.
In other words, top level domain label.
Assuming the resolver has no cash records to accelerate the process, which is the worst case scenario,
the resolution process starts with a query to one of the root servers.
The root servers are running all over the world, and each one knows DNS information about top level
domains or TMD such as dot com.
So to begin answering your query, the resolver asks a root server for DNA information about dot com.
So there are 13 sets of root servers and more than 300 locations around the world.
Each tailed DNS name server stores the address information for second level domains within the top level
domain dot dotcom in our example.
The second level domain is Google dot com, when your query reaches the detailed server, the TLD server
answers with the IP address of the domain name server, which will provide the next piece of the puzzle.
So this is the final step of a dress resolution.
The recursive resolver sends the query to the domain name server.
This DNS server knows the IP address for the full domain mail that Google dot com, and that answer
is returned to the recursive resolver.
Now that the recursive resolver knows the IP address for the domain name in your query, the recursive
resolver tells the browser what the IP address is.
So finally, your browser can send a request to the Web site to retrieve the website's content using
the IP address it just learned.
This whole process might seem, well, complicated, it certainly sounds odd to talk it up, but really
takes very little time at all.