ROLL NO: 13015411
COMPUTER SCIENCE & ENGINEERING
Question: What Is a DNS Server?
The Domain Name System is a standard technology for
managing public names of Web sites and other Internet
DNS service must translate the name into the corresponding
IP address. For example, the domain
name www.example.com might translate to 126.96.36.199.
Now the question is
How DNS server works?
When we visit a domain such as dyn.com, our computer
follows a series of steps to turn the human-readable web
address into a machine-readable IP address.
Step 1: Request information
The process begins when we ask our computer to resolve a
hostname, such as visiting http://dyn.com. The first place
our computer looks is its local DNS cache which stores
information that our computer has recently retrieved.
Step 2: Ask the recursive DNS servers
If the information is not stored locally, our computer queries (contacts)
our ISP’s recursive DNS servers. Recursive servers have their own caches
Step 3: Ask the root nameservers
If the recursive servers don’t have the answer, they query the root
nameservers. They don’t know the answer, but they can direct our query
to someone that knows where to find it.
Step 4: Ask the TLD nameservers
The root nameservers will look at the first part of our request,
reading from right to left — www.dyn.com — and direct our query to
the Top-Level Domain (TLD) nameservers for .com. Each TLD, such
as .com, .org, and .us, have their own set of nameservers, which act
like a receptionist for each TLD.
Step 5: Ask the authoritative DNS servers
The TLD nameservers review the next part of our request —
www.dyn.com — and direct our query to the nameservers
responsible for this specific domain.
Step 6: Retrieve the record
The recursive server retrieves the A record fordyn.com from
the authoritative nameservers and stores the record in its local
Step 7: Receive the answer
Our computer stores the record in its cache, reads the IP
address from the record, then passes this information toour
This entire process, from start to finish, takes only milliseconds
Why we use DNS server?
We can think of DNS as being like a phone book. Those people we
want to call frequently, we usually either know their numbers or
have their numbers on speed dial/saved on our cells/etc. But
sometimes we need to call someone that isn't in our speed dial or
memory. That is where the Domain Name System comes in. When
we, for example, type in google.com into our web browser, our
service provider sends that address to a (usually our ISP's) DNS
server, which then looks at the info "google.com" sent to it, looks it
up and says, "it's IP address is 188.8.131.52," and sends that info
back to your home computer. Your computer then knows where to
find the Internet resource.
Benefits of DNS Server
1.Capable of providing security.
2.Errors are automatically checked.
3.Ease of using.
4.Flexibility of use.
5.Consistent to use.
6.Easy to maintain.
7.No need to memorise numbers.
8.Domain names makes / gives a kind of sense to hyper links when
a name is given instead of a string of numbers .
Problems we face by using
Breakdown of DNS would crash the world wide web though
there are many root servers and backup servers targetting
DNS servers at particular key locations would do lot of harm