What is DNS ? Explain the types of DNS ? DNS explained

DNS :-                                                                                                                        
The full form of DNS is Domain Name System . All the computers or devices which are connected to the internet are provided with IP Address . At present this ip address is of 32 bit and in a block of 4 e.g. (192.168.2.3)

It is difficult for the user to remember IP address so to resolve this problem Domain Name System is introduced .

Domain Name System is a service of internet which is used for domain name to IP address and IP address to domain mapping .

What is Domain Name ?                                                                                          
It is a unique name through which websites is identified e.g. yahoo.com , google.com , etc. At the initial point of time all the websites had their IP addresses e.g. 192.168.1.6 .

There is communication between websites by IP address . But for user it is difficult to remember the IP Address but it is easy to remember the domain name .

What is Domain Name Space ?                                                                               
Structure of DNS data base is called as Domain Name Space . Structure of DNS database is like inverted tree whose top level ( Zero ) is called as ROOT . There are total of 128 level in the DNS database structure . There are 0-127 level in DNS Structure . Whose zero level is called as ROOT . ROOT node is also called as Null Level .

ROOT Level :-                                                                                                          
This level is also called as zero level which is denoted by dot (.) . Root level is null level which means nothing .

SECOND Level Domain :-                                                                                      
This is a part of top level domain name which comes just after the top level domain name . e.g. yahoo.com , flipkart.com .

SUB Domain :-                                                                                                         
To represent the unique content of a website SUB Domain is used . e.g. ( tech.blogspot.com ) in which tech is the sub domain , blogspot is second level domain , and com is top level domain .

How does DNS work ?                                                                                            
Domain name system works as a service which translate ip address to domain name and domain name to ip address .

when we enter domain name in a web browser , DNS service translate it to ip address and send this request to the server , And server give response in the form of IP Address but before it reaches to the browser DNS translates it to domain name , due to which user are unaware that the communication has done with IP Address but not by the domain name .
Like this DNS serive work .

Types Of Domain Level :-                                                                                      
There are varous domain level , but some important domain level are given below :-

1.TLD :- Top Level Domain                                                                                   
The Domain that comes just after (.) dot is called as Top Level Domain . This type of domain were used at first . Search engines give importance to this types of domain due to which website who use this type of domain starts to rank easily .

e.g..com ( commercial ), .gov ( government ) .

2.CCTLD :- Country Code Top Level Domain                                                  
This type of domain names are named after countries . In this type of domain after (.) two characters are used

e.g. .in (india) , .tw (taiwan)

Types Of Domain Name :-                                                                                    

1.FQDN
2.PQDN

1.FQDN :-                                                                                                              
The full form of FQDN is Fully Qualified Domain Name . If the level of domain name is terminated from null string then this type of domain names are called as FQDN ( Fully Qualified Domain Name ) .

2.PQDN :-                                                                                                              
The full form of PQDN is Partially Qualified Domain Name . If the level of domain name is not terminated from null string then this type of domain names are called as PQDN ( Partially Qualified Domain Name ) . Some part of host full name is called as Partially Qualified Domain Name .

e.g. gov.in

DNS In Internet :-                                                                                                
DNS is a NAME RESOLUTION SERVICE which is used in various platforms . In internet domain name space is divided into three categories :-
1.Inverse Domain
2.Generic Domain
3.Country Domain

1.Inverse Domain :-                                                                                             
All  the domains which are used to map in IP address , those domains are called as Inverse Domain .

2.Generic Domain :-                                                                                            
All those domains whose name are given accoring to the nature of organization are called as Generic Domain .
e.g. .com (commercial), .org (organization) , etc .

3.Country Domain :-                                                                                           
All those domain whose names are given on the basis of country are called as Country Domain .
e.g. .in (india) , .tw(taiwan)

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