Domain Name System

A Domain name system is generally composed of name servers,resolvers and their communication protocol.Together they create a distributed internet directory service capable of translating IP addresses and host domain names.
Nearly all internet services today rely on domain name system to function and without this mechanism they cannot operate.
When the internet first began,it was a small community of universally known IP addresses.As it grew,it was determined that memorising and identifying servers by numbers was difficult.Hence,because numbers were more difficult to remember names were developed for servers.For instance,instead of saying 10.10.10.1 you could say ajet.com.However,there neede to be a way to link the IP address to a domain name.To diminish this burden,a text file known as hosts.txt was created which contained a listing of server IP addresses and descriptive host names.For example:
10.10.10.1 ajet
10.10.10.2 server
Hence,if someone wanted to use telnet to connect to the system, he or she could either telnet 10.10.10.1 or telnet ajet and it would work.
Without DNS,you would enter http://10.10.10.1 into your web server instead of http://www.ajet.com,you would send email to ajet@12.15.23.78 instead of koko@testing.com and you would have to configure your instant message chat client to know that niger online is at 45.23.12.89.
Essentially,the internet can still function without DNS but it would mean you would have to remember numbers instead instead of names.If you know that a company is called ajet,you can make a good guess at what its domain name might be, but would have no idea what their IP address is.

Note that IP addresses alone are difficult to remember.Hence,DNS provides a means of translating addresses into names tat can be descriptive and representative of a site and its contents.
Domain names are registered by organizations through network providers.They are generally not shared across organizations and are descriptive of the information provided within the domain whereas top level domains are shared across organizations and examples are .com,.edu and .org.
Top level domain names were initially broken down by organization type such as gov for government,edu for education and com for commercial.However,as the internet became a global network,people wanted to be able to distinguish by country.Now if you reside in Nigeria which is my home country for instance and your company is named ajet,because ajet.com is taken,you could register ajet.ng.

Note that of all servers in an organization,DNS is the one that every organization should have in other to allow people to use domain names to access their company's resorces.DNS servers are often installed on old servers that are not capable of servicing large central processing units and bandwidth intensive applications.Furthermore,DNS servers require little manual maintenance,hence they are often neglected when it comes to log monitoring.This a serious security concern because gaining access to a DNS server can provide broader access to clients that rely and use it.Securing DNS requires that the system is properly configured and properly designed whereas most organizations are more interested in functionality and not security.
When selecting the proper DNS architecture for an organization,the most important design is to implement a split-split architecture.This design should take care of no less than two internal DNS servers for every 500 users.Although firewalls and routers are functioning properly,without the DNS architecture your users internet service will become useless.For users that operate over wide area networks,it is required to locate servers within close proximity so that each query does not have to traverse across the distance of yhe wide area network


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