is DNS server and Domain Name System?
What is DNS server and Domain Name System?
Ever wonder why DNS systems came into existence? Efficiency. Every
computer has a distinct IP address, and the Internet needed an elite
method for obtaining these addresses and for managing the system
as a whole. Enter ICANN.
The Internet Corporation for Assigned Names and Number manages
the DNS root of the Internet domain namespace. ICANN's role is to
manage the assignment of identifiers, ensuring that all users have
The DNS system is run by a series of servers called DNS servers.
ICANN manages the root DNS domains, under which are the top-level
domains. It also manages:
Organizational domains Geographical domains Reverse domains
Beneath the top-level domains are other naming authorities such
as Nominet, the UK's naming authority.
How does a DNS Query work?
The process occurs in two parts. Firstly, a name query begins at
a client computer and is passed to DNS client service for resolution.
When the query cannot be resolved locally, DNS servers are queried.
For example, when a web browser calls the fully qualified domain
name www.discountdomainsuk.com, the request is passed on to the
DNS client service to resolve the name by using locally cached information.
If the query is held in the cache, then the process is complete.
If, however, the query cannot be answered locally, the DNS client
service uses a server list (ordered in sequence) to query external
DNS servers. When a DNS server receives a query, it first checks
to see if it is authoritive for that domain name. If it is authoritive,
it resolves the name, and the process is complete.
If the DNS server is unable to resolve the query, it in turns queries
other DNS servers, using a process known as recursion. DNS servers
make use of root hints to assist in locating DNS servers, which
are able to provide the required result. In this way, DNS queries
are minimised and the Internet is able to operate quickly and effectively.
A typical query may run as follows:
Client contacts Nameserver A looking for www.discountdomainsuk.com.
Nameserver A checks its cache, but can't answer, so it queries
a server authoritive for the Internet root.
The root server responds with a referral to a server authoritive
for the .com domains. NameserverA queries the the .com server and
gets referred to the server authoritive for www.discountdomainsuk.com.
Nameserver A queries this server and gets the IP address for www.discountdomainsuk.com.
Nameserver A replies to the client with the IP address.
Queries can return answers that are authoritive, positive, negative
or referral in nature. In the event of a negative answer, another
DNS server is queried.
Clare Lawrence is CEO of Discount Domains
Ltd - A leading UK provider of Domain name registration and Web
Hosting services. Please feel free to re-publish this article provided
this reference box remains together with a hyperlink to http://www.discountdomainsuk.com
Clare can also be contacted on Clare@discountdomainsuk.com.