Everything You Need to Know About Domain Space
TCP/IP uses an IP address to uniquely identify the host to the internet, however remembering the IP address all the time is difficult. So instead of using an address, it uses names and thus, the DNS provides this mapping address to a name and name to address.
Each node is called a tree. It has a Domain name which is separated by dot (.) If the label is terminated by a null string, it’s called a fully qualified domain name; for example xxx.edu.com, if the label is not terminated by a null string, it’s called a partially qualified domain. Thus, we need to supply only the missing parts to create FQDN. Suppose the fuda.com site wants to go to an IP address of the tree computer. It defines its tree, the DNS client, adds suffix bbb.fuda.com before passing address to DNS server.
DNS Server: is used to distribute the information among many computers. This divides the whole space into lots of domains based on the first level. This root server alone creates many domains in the first level node. After this, the first level node also creates many sub domains. So makes a hierarchy of name servers.
A root server is a server whose zone consists of a whole tree. Primary server creates, maintains and updates information about its zone. A secondary server gets information from the primary server. It transfers the whole information about a zone from another server and stores files into a local disk.
A DNS is divided into three different sections:
1) Generic Domain: defines a host according to its behavior. For example:
- Com – commercial organization
- Edu – educational Institution
- Gov – government institution
- Net – network support center, etc
2) Country Domain: it uses two character country abbreviations. For example imp.ca.us can be said as Imp Collage in California in the United States.
3) Inverse Domain: it finds a domain name for a given IP address. Its reading a domain label from bottom to the top.18.104.22.168 will be read as 22.214.171.124.in-addr.arpa.
The process of mapping a name to address and address to name is called resolution.
Mapping name to address:
This resolver gives a domain name and asks server to find Its IP address. The server uses a generic domain or country domain.
Mapping Address to name:
A client gives the IP address and server is needed to improve its Domain name. For this server, it makes use of inverse domain. In this, the IP address is reserved and two label in –add and area add.
The client can ask for an answer from a name server. If the server is authorized, it checks its database and respond. If the server is unauthorized it sends request to another server and waits for it to respond. So it’s called recursive resolution.
DDNS (Dynamic Domain Name Space) updates DNS master files automatically. DNS use either a UPD or TCP service using a well-known port number 53.UPD is used when the size of the response message is less than 512 bytes.