by numbers, because that's how computers and other similar devices talk and

identify with each other over a network, which is by using numbers such as IP

addresses. Humans on the other hand are accustomed to using names instead of

numbers,

whether is talking directly to another person or identifying a country,

place, or thing, humans identify with names instead of numbers. So in order to

bridge the communication gap between computers and humans and make the

communication of a lot easier

networking engineers developed DNS, and DNS stands for a domain name system. And DNS

resolves names to numbers, to be more specific

it resolves domain names to IP addresses. So if you type in a web address in your

web browser, DNS will resolve the name to a number because the only thing

computers know are numbers. So for example if you wanted to go to a certain

website you would open up your web browser and type in the domain name of

that website, so for example let's use yahoo.com. Now technically you really

don't have to type in yahoo.com to retrieve the Yahoo web page, you can just

type in the IP address instead if you already knew what the IP address was, but

since we are not accustomed to memorizing and dealing with numbers,

especially when there are millions of websites on the internet, we can just

type in the domain name instead and let DNS convert it to an IP address for us.

So back to our example, when you typing yahoo.com your web browser

the DNS server with search through its database to find a matching IP address

for that domain name, and when it finds it it will resolve that domain name to

the IP address of the Yahoo web site, and once that is done then your computer is

able to communicate with a Yahoo web server and retrieve the webpage. So DNS

basically works like a phone book, when you want to find a number, you don't look

up the number first, you look up the name first then it will give you the number.

So to break this down into further detail let's examine the steps that DNS

takes.

So when you type in yahoo.com in your web browser and if your web browser

or operating system can't find the IP address in its own cache memory, it will

send the query to the next level to what is called the resolver server to resolver

server is basically your ISP or Internet service provider, so when the resolver

receives the query, it will check its own cache memory to find an IP

address for yahoo.com, and if it can't find it it will send the query to the

next level which is the root server.

The root servers are the top or the root of a DNS hierarchy. There are 13 sets of

these root servers and they are strategically placed around the world,

and they are operated by 12 different organizations and each set of these root

servers has their own unique IP address. So when the root server receives the

query for the IP address for yahoo.com, the root server is not going to know

what the IP address is, but the root server does know where to send the

resolver to help it find the IP address. So the root server will direct the

resolver to the TLD or top-level domain server for the dot-com domain. So the

resolver will now ask the TLD server for the IP address for yahoo.com.

The top level domain server stores the address information for a top-level

domains, such as.com and.net dot org and so on. This particular TLD server manages

the dot-com domain which yahoo.com is a part of.

So when a TLD server receives the query for the IP address for yahoo.com, the

TLD server is not going to know what the IP addresses for yahoo.com. So

the TLD will direct the resolver to the next and final level, which are the

authoritative name servers.

So once again the resolver will now ask the authoritative name server for the IP

address for yahoo.com.

The authoritative name server or servers are responsible for knowing everything

about the domain which includes the IP address. They are the final authority. So

when the authoritative name server receives the query from the resolver, the

name server will respond with the IP address for yahoo.com. And finally the

resolver will tell your computer the IP address for yahoo.com and then your

computer can now retrieve the Yahoo web page.

It's important to note that once the resolver receives the IP address, it will

store it in its cache memory in case it receives another query for yahoo.com so

it doesn't have to go through all those steps again.