In the world of networking, computers don’t go by names like humans do, they are going by numbers, because that’s how computers and other similar devices talk and identify with one another over a network, which is by using numbers such as IP addresses.
Humans on the opposite hand are familiar with using names rather than numbers, whether is talking to another person or identifying a country, place, or thing, humans identify with names rather than numbers. So as to bridge the communication gap between computers and humans and make communication of tons 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 during a web address in your browser, DNS ( domain name system ) will resolve the name to a number because the only thing computers know are numbers.
So as an example, if you wanted to go to a particular website, you’d open up your browser and type in the name of that website, so for example let’s use yahoo.com. Now technically you actually do not have to type in yahoo.com to retrieve the Yahoo website, you’ll just type in the IP address instead if you already knew what the IP address was, but since we aren’t familiar with memorizing and handling numbers, especially when there are uncountable websites on the web, 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, once you type in yahoo.com your browser the DNS server with search through its database to find a matching IP address for that name, and when it finds it, it’ll resolve that domain name to the IP address of Yahoo web site, and once that’s done then your computer is able to communicate with a Yahoo web server and retrieve the webpage.
So, DNS basically works sort of a phone book, when you want to find a number, you do not search the number first, you search the name first, then it’ll give you the number. So, to interrupt this down into further detail let’s examine the steps that DNS takes. So, once you type in yahoo.com in your browser and if your browser or operating system can’t find the IP address in its own cache memory, it’ll send the query to the next level to what’s called the resolver server.
The resolver server is basically your ISP or Internet service provider, so when the resolver receives the query, it’ll check its own cache memory to find an IP address for yahoo.com, and if it can’t find it it’ll send the query to the next level which is that the root server.
The root servers are the highest or the basis of a DNS hierarchy. There are 13 sets of those root servers and they are strategically placed around the world, and that they are operated by 12 different organizations and every set of those root servers has its own unique IP address. So, when the root server receives the query for the IP address for yahoo.com, the root server isn’t going to know what the IP address is, but the root server does know where to send the resolver to assist it find the IP address. therefore, 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 domain, such as .com, .net, .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 isn’t going to know the IP addresses for yahoo.com. therefore, the TLD will direct the resolver to the next and final level, which are the authoritative name servers. So once more 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’re the ultimate 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 eventually, the resolver will tell your computer the IP address for yahoo.com then your computer can now retrieve the Yahoo website. it’s important to notice that once the resolver receives the IP address, it’ll store it in its cache memory just in case it receives another query for yahoo.com so it doesn’t need to go through all those steps again.