DNS - domain name system

1. Government Engineering College –
Modasa
SUBJECT : COMPUTER NETWORKS (2140709)
TOPIC : DOMAIN NAME SYSTEM
PRESENT BY : GUIDED BY :
MILAN BHATIYA PROF. V. V. NAYAK

2. DNS
Domain Name System
INTRODUCTION TO DNS,
THE INTERNET'S DISTRIBUTED NAMING SYSTEM

3. What is the Domain Name System ???
it's like a phone book
DNS is a directory service
DNS is an identity mechanism
DNS is a namespace structure
DNS is an abstraction layer

4. • Simple beginnings:
hosts.txt
• Today modern DNS is
managed like a distributed
phone book

5. An Analogy to Start…
•Servers on the Internet have IP Addresses, like a telephone
number.
•A Domain Name (like facebook.com, twitter.com, and amazon.in)
is A Name Badge On The Internet.
•DNS (domain name system) service is the Internet’s Telephone
Book.
•If you have someone’s name, you can look up Their phone
number.

6. maps
server1.www.Facebook.com
To
66.220.159.255
maps
hostnames
to
IP addresses

7. The Goal: Your Customers Connect

8. Domain Names
• Domain Names are registered through ICANN accredited
registrars – companies who work with domain name registries.
• Example
Registrars:
– GoDaddy
– Network Solutions
• Example
Registries:
.com, .net, .org, .info, .biz, .mobi, .co.in, .de, .dk

9. DNS Components
There are 3 components:
• Name Space:
Specifications for a structured name space and data associated with the names
• Resolvers:
Client programs that extract information from Name Servers.
• Name Servers:
Server programs which hold information about the structure and the names.

10. With databases for each Domain in
the TLD
<root>
.com .in
Facebook.com Amazon.in
Youtube.com

11. Availability and Performance
DNS Must Always be available otherwise, web, email, video, and Online services Are down.
Need To build Redundancy into The network, and Maintain specially systems.
Risk of A attack on Your DNS?
When things Go wrong, People say: