Domain Name System (DNS) | Key components of DNS
Internet's system for translating alphabetic names into numeric IP addresses.
The Domain Name System is a distributed database with hierarchical structure and serve the basis for name resolution process in TCP/IP network.
The process of DNS resolution involves converting a hostname (such as www.example.com) into a computer-friendly IP address (such as 188.8.131.52). Just as we require a street address to find a particular home in the same way IP address is necessary to find a particular Internet device.
When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example.com) and the machine-friendly address necessary to locate the example.com webpage.
Domain Name System (DNS) converts the name of a Web site to an IP address and vice-versa. The reverse process is called Reverse Domain System (RDNS).
Key Components of DNS
- Domain name space
1. Domain Names Space -
Domain Name Space is defined such that the names of all similar components must be similarly structured, but similarly identifiable. The full DNS name must point to a particular address.
The fully qualified domain name (FQDN) of the host mail is mail.google.com. No two hosts can have the same FQDN.
2. Zones -
All top-level domains, and many domains at the second and lower levels, are broken into zones.
3. Name Servers -
The programs that store information about the domain namespace are called nameservers. Nameservers generally have complete information about some part of the domain namespace, called a zone
- Primary name server (Master)
- Secondary name server (Slave)
4. Resolver -
Resolvers are the clients that access nameservers. Programs running on a host that need information from the domain namespace use the resolver. The resolver handles:
Querying a nameserver.
Interpreting responses (which may be resource records or an error).
Returning the information to the programs that requested it.
In BIND, the resolver is a set of library routines that is linked to programs.
Ex. gethostbyname() in standard socket library in C prog. Language
- hosts: dns files
- On Clients
- On Server
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