How a Domain Name System (DNS) works
What is a DNS (Domain Name System)?
The Domain Name System (DNS) is a hierarchical naming system built on a distributed database for computers, services, or any resource connected to the Internet or a private network. Most importantly, it translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide.
An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. For example, the domain name www.example.com translates to the addresses 220.127.116.11 (IPv4) and 2620:0:2d0:200::10 (IPv6). more on wiki…
What is a DNS Hierarchy?
DNS Hierarchy is process which we go in deep to find how a Domain name entered by user is been resolved and communicate back to the user by Domain Name System. We could say; this is a long term process that we’re going deep into all DNS Levels. Because, Domain Names are hierarchical and each part of a domain name is referred to as either the root, top level, second level or as a sub-domain. To allow computers to properly recognize a fully qualified domain name, dots are placed between each part of the name. All resolvers treat dots as separators between the parts of the domain name. The fully qualified domain name is split into pieces at the dots and the tree is searched starting from the root of the hierarchichal tree structure. All resolvers start their lookups at the root, therefore the root is represented by a dot and is often assumed to be there, even when not shown. Example of a Fully Qualified Domain Name (FQDN);
mail..com. (theres a dot after .com which refers the Root DNS)
So, How does this DNS Hierarchy actually process..??
A user request for www..com on his web browser as he wants to enter the website…..! (Assume that the user is connected to internet using a LAN based environment from his residence, office… etc). Now, this is how the DNS servers resolves and get back to the address; each Levels will be explained to you..>>
Through the Local DNS Server a request will be sent to the ISP DNS Server. From the ISP DNS server, another request will be sent to the Root DNS Server (this server can divide request as per the domain such as .com, .gov, .edu… etc) will identify the .com servers. And then the next Level is the Top Level DNS Server (this server can identify the proper .com domain) which has only the .com domains. From the Top Level DNS Server itself, a request will be sent to the Second Level DNS Server (this server will have all the subdomains, records related to warelk.com such as about..com, blog..com …etc) to identify. Second Level DNS Server will track down & identify all the sub-domains & host record as per the user request, then it will resolve and send you back the website as a result. (by Azker M)
For example, in the figure below, .edu is the top level domain, berkeley is the second level domain, and .cs is the sub-domain of berkeley. Eos is the host name. A DNS server would store the IP address of the host where its name resides in the tree. (by InetDeamon)
I will explain All Levels of DNS Servers and in which process that they take part in my next post. Until, that enjoy learning & sharing with your pals… 🙂