7/31/2019 DNS Server New
1/23
vrm 1
Domain
Name Server
7/31/2019 DNS Server New
2/23
vrm 2
Domain Name Server(DNS)
Why DNS
History of DNSDNS hierarchy
Architecture
Domain Name Resolution
7/31/2019 DNS Server New
3/23
vrm 3
Why Domain Name Service?
Each computer ON Internet has two addresses a numericIP address (such as 241.111.4.142") and a host name suchas www.bsnl.co.in.
Computer in the Network understands only IP address.
IP address may change whenever hosts are relocated on anetwork or from one network to another
It is easy to remember common language names than IPbased name format .
It is required to translate the domain name entered by theend user into its IP address to enable the transporting of
packets over networks.
DNS performs this translation using a database of hostinformation
7/31/2019 DNS Server New
4/23
vrm 4
Domain Name Server
It is a database holding the IP address against domain
name.
In the early days the DNS was stored as a simple textfile located on each computer on the internet.
It became impossible to administer this database as
the host on internet grew in fast manner.
Hence DNS become a distributed database.
Portions of DNS database are stored on local name
servers and updated local DNS administrators.
7/31/2019 DNS Server New
5/23
vrm 5
History of DNS
Initially started by ARPANet
Host information collected and organized by
InterNIC.The information file is called Hosts file or
Phone Book.
In 1980 DARPA shifted its protocol platform to
TCP/IP
This made to grow the network abundantly.
7/31/2019 DNS Server New
6/23
vrm 6
Due to the fast growing nature of Internet it become
impossible to have all the host names in a centrally
organized Host file.
ARPA adopted new method of maintaining Host
name The Domain Name Service.
7/31/2019 DNS Server New
7/23vrm 7
In this system eight numbers of top level domainsare defined.
Sites are categorized and grouped in to the top level
domains.Each domain in the network would maintain a
Domain Name Server.
This server would supply information about thespecific hosts with in the domain it served to otherservers.
7/31/2019 DNS Server New
8/23vrm 8
Advantages of the DNS
Same Domain Name can repeat on different
domains.
The Domain administrator can add new host
without prior intimation to other hosts.
Distributed administration.
7/31/2019 DNS Server New
9/23vrm 9
Top Level Domains
.com:-Commercial organizations.edu:-Educational organizations
.gov:-Government organizations
.mil:-Military organizations
.net:-Networking organizations
.org:-Non-Commercial organizations
.int:-International organizations
.arpa:-ARPA Domain*
7/31/2019 DNS Server New
10/23vrm 10
Control on DNS
IAB
Internet Architecture Board
7/31/2019 DNS Server New
11/23vrm 11
Geographical domains
In addition to the top level domains IAB decided
to have geographical domains.
Geographical domain name with two alphabet.
Eg: in:- India, uk:- Britain ,fr:-France
7/31/2019 DNS Server New
12/23vrm 12
Domain Name Hierarchy
Domain name can be up to 63 character in length.
May contain digits or hyphens.
Should start with an alphabet.
Not case sensitive.Each domain has a domain server.
The collection of hosts which the server can give a name or
IP address is called The Zone of authority
Zone of authority defines the boundary of the zone.
The entire collection of domains is called domain name
space.
7/31/2019 DNS Server New
13/23vrm 13
Domain Name Hierarchy
A domain name which can be identified uniquely in a
domain is called fully qualified domain name(FQD)
A domain can have sub domains.
Eg:www.yahoo.com,www.rttctvm.bsnl.co.in
www.ernakulam.sancharnet.in are
fully qualified domain names.
http://www.yahoo.com/http://www.yahoo.com/http://www.rttctvm.bsnl.co.in/http://www.rttctvm.bsnl.co.in/http://www.ernakulam.sancharnet.in/http://www.ernakulam.sancharnet.in/http://www.ernakulam.sancharnet.in/http://www.rttctvm.bsnl.co.in/http://www.yahoo.com/7/31/2019 DNS Server New
14/23vrm 14
Domain Name Hierarchy
in
sancharnet vsnl satyam
ernakulam chni bgr
www.sancharnet.inwww.satyam.inwww.sancharnet.ernakulam.in
7/31/2019 DNS Server New
15/23vrm 15
Domain Name-space
.com
.edu.in
7/31/2019 DNS Server New
16/23vrm 16
.in -domain name space
sancharnet
satyam
7/31/2019 DNS Server New
17/23vrm 17
.sancharnet.in -domain name space
ernalulam chni
7/31/2019 DNS Server New
18/23vrm 18
How to resolve Domain Name query?
You are requesting www.yahoo.com from a sanchernet client
Query sent to sancharnet nameserver
Query sent to .com rootname server
Response from the root name server
Ask the guy w.x.y.z
Query to name server w.x.y.z
Response from name server w.x.y.z
The address of www.yahoo.com is r.s.t.u
7/31/2019 DNS Server New
19/23vrm 19
Architecture of DNS
There are two type of name servers Primary master and
secondary master.
Primary master contains the database for its zone of
authority.
Secondary master stores a copy of primary master.
Name servers with zone of authority a top level domain is
called root name server.
7/31/2019 DNS Server New
20/23vrm 20
DNS software
The server application developed for DNS function is
called BIND.
BIND Berkeley Internet Name Domain
BIND is developed in UNIX platform.
A ported version of BIND is developed later for Windows
NT platform.
Microsoft developed its own DNS software for working inWindows NT platform.
7/31/2019 DNS Server New
21/23vrm 21
InterNIC
Controls the Domain Name
registration
7/31/2019 DNS Server New
22/23
vrm 22
Controls the Domain Name
Registration in Asia Pacific
APNIC
7/31/2019 DNS Server New
23/23
23
Controls the Domain Name
registration in in domain
C-DAC(formerly NCST)Centre for Development of Advanced Computing,
Mumbai (formerly known as National Centre
forSoftware Technology)