SlideShare a Scribd company logo
1 of 38
GL

BAL

Institute of Information Technology
A Presentation on
Domain Name System
Group Name :-

G2

Group Members :- Gaurav Kumar

Rohitash kumar
Nitesh Kumar
Rahul Baghla
 Key terms
 What is internet
 How do they connect
 History of the DNS

 Introduction to the DNS

 Components of the DNS
 The namespace
 The servers
 The resolvers

 Conclusion
 The internet is a global system of interconnected

computer networks . It is a network of networks that
consists of millions of private and public , academic ,
business and government networks of local to global
space that are linked by transmission media such as
copper wires , fiber optic cables , wireless connections
and other technologies .
 A network of computers connected to each other

is called internet and these computers needed to
know which computer they were connecting to, so
each computer was given a unique number – an IP
(Internet Protocol) number. E.g. 121.245.078.2
 There was the ARPANET’s HOSTS.TXT file
 Each computer on the network retrieved a file called HOSTS.TXT
 HOSTS.TXT mapped every ARPANET host’s name to its IP address.
 The HOSTS.TXT file mapped numerical addresses to names.
 Allows users to specify an IP address (e.g. 192.0.34.166) to use for a
host name (e.g. www.google.com) without checking DNS.


Systems based on a hosts file have inherent limitations
 The obvious requirement that every time a given computer's address

changed, every computer that seeks to communicate with it would
need an update to its hosts file.
 Consistency
 The network changed more quickly than the file was updated

 Name collisions
 No two hosts could have the same name
 “Good” names quickly exhausted
 There was no good method to prevent duplicate names
 Human intervention was required

 Traffic and load
 The traffic generated by downloading the file became

significant
 Download time sometimes longer than update period

 The model didn't scale well
 ARPANET powers-that-were launched an investigation into

replacement for HOSTS.TXT
 Requirements:
 Decentralized administration
 With data updated locally, but available globally
 A hierarchical name space
 To guarantee unique names

 Paul V. Mockapetris, American computer scientist and

Internet pioneer, together with Jon Postel, invented the
Internet Domain Name System (DNS).
 The domain name system is usually used to translate a

host name into an IP address and vice versa.
 Domain names comprise a hierarchy so that names are
unique, yet easy to remember.
 DNS implements a distributed database to store
domain name and address information for all public
hosts on the Internet.
 Defines a hierarchical namespace where each level

of the namespace is separated by a “.”
A fully qualified domain name is processed from right
to left for its translation into the corresponding IP address. A
fully qualified domain name can be made up of a top level
domain (TLD), second level domain (SLD) and sub domains
 The Name Space
 The Servers
 The Resolver
 The name space is the structure of the DNS database
 An inverted tree with the root node at the top
 Each node has a label
The root node
""

top-level node

second-level node

third-level node

top-level node

second-level node

second-level node

third-level node

top-level node

second-level node

third-level node

second-level node
 A domain name is the sequence of labels from a node to the

root, separated by dots (“ . ”), read left to right
in
 One domain is a subdomain of another if its apex

node is a descendant of the other’s apex node
 More simply, one domain is a subdomain of
another if its domain name ends in the other’s
domain name
 So abc.webs.com is a subdomain of
 webs.com
 com
 webs.com is a subdomain of com
 The Name Space
 The Servers
 The Resolver
 Name servers store information about the name

space in units called “zones”
 The name servers that load a complete zone are said to

“have authority for” or “be authoritative for” the zone
 Usually, more than one name server are

authoritative for the same zone
 This ensures redundancy and spreads the load

 Also, a single name server may be authoritative for

many zones
Two main types of servers
 Local name servers:

Each ISP, company has local (default) name server

Host DNS query first goes to local name server
 Authoritative name server:

For a host: stores that host’s IP address, name

Can perform name/address translation for that host’s name
 Contacted by local name server that can not resolve name
 Root name server:
 contacts authoritative name server if name mapping not

known
 Gets mapping & returns mapping to local name server
 The Name Space
 The Servers
 The Resolver
 Name resolution is the process by which client and

Local name servers cooperate to find data in the
name space.
 A Local name server receives a query from a client ,
looks for the answer in its database
 If the answer isn’t in the database and the server isn’t

authoritative for the answer, the answer must be
looked up.
 Let’s look at the resolution process step-by-step:

Client Computer

www.google.com
 The client computers asks its Local name server,

for www.google.com’s address

Local Name Server

What’s the IP address
of www.google.com?

Client Computer

www.google.com
 The Local name server asks a Root name server , for

www.google.com’s address

Local Name Server

What’s the IP address
of www.google.com?

Client Computer

www.google.com

Root Server
 The root server refers Local name server to the .com

name servers.

Local Name Server

Client Computer

www.google.com

Root Server

Here’s a list of the
.com name servers.
Ask one of them.
 The Local name server asks .com name server,

for www.google.com’s address
What’s the IP address
of www.google.com?

Root Server

Local Name Server

.com Server

Client Computer

www.google.com
 The com name server refers Local name server

to the google.com name servers
Here’s a list of the
google.com name
servers. Ask one
of them.
Root Server

Local Name Server

.com Server

Client Computer

www.google.com
 The Local name server asks google.com name server,

for www.google.com’s address
What’s the IP address
of www.google.com?

Root Server

Local Name Server

Google.com Server

.com Server

Client Computer

www.google.com
 The google.com name server responds with

www.google.com’s address

Root Server

Local Name Server

Here’s the IP
address for
www.google.com

Google.com Server

.com Server

Client Computer

www.google.com
 The Local name server responds to client

computer with www.google.com’s address
Here’s the IP
address for
www.google.com
Root Server

Local Name Server

Google.com Server

.com Server

Client Computer

www.google.com
 After the previous query, the Local name server now knows:
 The names and IP addresses of the com name servers

 The names and IP addresses of the google.com name servers
 The IP address of www.google.com
 Let’s look at the resolution process again

Client Computer

www.google.com
 The client computer asks its Local name server,

for www.google.com’s address

Root Server

Local Name Server

What’s the IP address
of google.com?

Google.com Server

.com Server

Client Computer

www.google.com
 The Local name server responds to client computer

with www.google.com’s address
Here’s the IP
address for
google.com
Root Server

Local Name Server

Google.com Server

.com Server

Client Computer

www.google.com
 DNS is like a phone book for the Internet. If we know a

person’s name but don’t know his mobile number, we
can simply look it up in a phone book. DNS provides
this same service to the Internet.
 When we visit www.google.com in a browser, our

computer uses DNS to retrieve the website’s IP address
of 173.194.69.147 .
DNS Domain Name System Explained in 40 Characters
DNS Domain Name System Explained in 40 Characters

More Related Content

What's hot (20)

Domain Name System
Domain Name SystemDomain Name System
Domain Name System
 
Domain name system (dns)
Domain name system (dns)Domain name system (dns)
Domain name system (dns)
 
Domain Name System DNS
Domain Name System DNSDomain Name System DNS
Domain Name System DNS
 
Presentation on dns
Presentation on dnsPresentation on dns
Presentation on dns
 
Presentation on Domain Name System
Presentation on Domain Name SystemPresentation on Domain Name System
Presentation on Domain Name System
 
Dns 2
Dns 2Dns 2
Dns 2
 
Dns ppt
Dns pptDns ppt
Dns ppt
 
Dhcp
DhcpDhcp
Dhcp
 
DNS - Domain Name System
DNS - Domain Name SystemDNS - Domain Name System
DNS - Domain Name System
 
Domain name system presentation
Domain name system presentationDomain name system presentation
Domain name system presentation
 
Dns presentation
Dns presentationDns presentation
Dns presentation
 
DNS (Domain Name System)
DNS (Domain Name System)DNS (Domain Name System)
DNS (Domain Name System)
 
Chapter 29 Domain Name System.ppt
Chapter 29 Domain Name System.pptChapter 29 Domain Name System.ppt
Chapter 29 Domain Name System.ppt
 
DNS ( Domain Name System)
DNS ( Domain Name System)DNS ( Domain Name System)
DNS ( Domain Name System)
 
Active Directory
Active DirectoryActive Directory
Active Directory
 
Dns
DnsDns
Dns
 
Dns ppt
Dns pptDns ppt
Dns ppt
 
Domain name system
Domain name systemDomain name system
Domain name system
 
Linux and DNS Server
Linux and DNS ServerLinux and DNS Server
Linux and DNS Server
 
Presentation: the domain name system
Presentation: the domain name systemPresentation: the domain name system
Presentation: the domain name system
 

Similar to DNS Domain Name System Explained in 40 Characters

Similar to DNS Domain Name System Explained in 40 Characters (20)

Dns
DnsDns
Dns
 
Linux basics andng hosti
Linux basics andng hostiLinux basics andng hosti
Linux basics andng hosti
 
The Application Layer
The Application LayerThe Application Layer
The Application Layer
 
Internet dns introduction
Internet dns introductionInternet dns introduction
Internet dns introduction
 
Application layer
Application layerApplication layer
Application layer
 
DNSPresentation.pptx
DNSPresentation.pptxDNSPresentation.pptx
DNSPresentation.pptx
 
domain network services (dns)
 domain network services (dns) domain network services (dns)
domain network services (dns)
 
D.N.S
D.N.SD.N.S
D.N.S
 
Domain Name System(ppt)
Domain Name System(ppt)Domain Name System(ppt)
Domain Name System(ppt)
 
Dns And Snmp
Dns And SnmpDns And Snmp
Dns And Snmp
 
1.1 DNS.ppt.ppt
1.1 DNS.ppt.ppt1.1 DNS.ppt.ppt
1.1 DNS.ppt.ppt
 
Presentation2.pptx
Presentation2.pptxPresentation2.pptx
Presentation2.pptx
 
How to configure dns server(2)
How to configure dns server(2)How to configure dns server(2)
How to configure dns server(2)
 
Lec 11(DNs)
Lec 11(DNs)Lec 11(DNs)
Lec 11(DNs)
 
What is a domain name system(dns)?
What is a domain name system(dns)?What is a domain name system(dns)?
What is a domain name system(dns)?
 
Dns
DnsDns
Dns
 
Domain Name Service
Domain Name ServiceDomain Name Service
Domain Name Service
 
Dns
DnsDns
Dns
 
Domain Name System (DNS)
Domain Name System (DNS)Domain Name System (DNS)
Domain Name System (DNS)
 
Dns1111111111
Dns1111111111Dns1111111111
Dns1111111111
 

More from Rahul Baghla

More from Rahul Baghla (10)

Holography
HolographyHolography
Holography
 
Sensor technology
Sensor technologySensor technology
Sensor technology
 
Lifi technology
Lifi technologyLifi technology
Lifi technology
 
Hacking
HackingHacking
Hacking
 
Computer +forensics
Computer +forensicsComputer +forensics
Computer +forensics
 
Computer virus
Computer virusComputer virus
Computer virus
 
Brain computer interface
Brain computer interfaceBrain computer interface
Brain computer interface
 
Bluetooth
BluetoothBluetooth
Bluetooth
 
Artificial intelligence
Artificial intelligenceArtificial intelligence
Artificial intelligence
 
Sixth sense technology
Sixth sense technologySixth sense technology
Sixth sense technology
 

Recently uploaded

Choosing the Right CBSE School A Comprehensive Guide for Parents
Choosing the Right CBSE School A Comprehensive Guide for ParentsChoosing the Right CBSE School A Comprehensive Guide for Parents
Choosing the Right CBSE School A Comprehensive Guide for Parentsnavabharathschool99
 
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptx
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptxDIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptx
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptxMichelleTuguinay1
 
Student Profile Sample - We help schools to connect the data they have, with ...
Student Profile Sample - We help schools to connect the data they have, with ...Student Profile Sample - We help schools to connect the data they have, with ...
Student Profile Sample - We help schools to connect the data they have, with ...Seán Kennedy
 
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdf
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdfVirtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdf
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdfErwinPantujan2
 
Transaction Management in Database Management System
Transaction Management in Database Management SystemTransaction Management in Database Management System
Transaction Management in Database Management SystemChristalin Nelson
 
4.18.24 Movement Legacies, Reflection, and Review.pptx
4.18.24 Movement Legacies, Reflection, and Review.pptx4.18.24 Movement Legacies, Reflection, and Review.pptx
4.18.24 Movement Legacies, Reflection, and Review.pptxmary850239
 
Production of Monoclonal Antibodies by Hybridoma Technology.pptx
Production of Monoclonal Antibodies by Hybridoma Technology.pptxProduction of Monoclonal Antibodies by Hybridoma Technology.pptx
Production of Monoclonal Antibodies by Hybridoma Technology.pptxAnupkumar Sharma
 
Influencing policy (training slides from Fast Track Impact)
Influencing policy (training slides from Fast Track Impact)Influencing policy (training slides from Fast Track Impact)
Influencing policy (training slides from Fast Track Impact)Mark Reed
 
Oppenheimer Film Discussion for Philosophy and Film
Oppenheimer Film Discussion for Philosophy and FilmOppenheimer Film Discussion for Philosophy and Film
Oppenheimer Film Discussion for Philosophy and FilmStan Meyer
 
Using Grammatical Signals Suitable to Patterns of Idea Development
Using Grammatical Signals Suitable to Patterns of Idea DevelopmentUsing Grammatical Signals Suitable to Patterns of Idea Development
Using Grammatical Signals Suitable to Patterns of Idea Developmentchesterberbo7
 
The State of AI in Insights and Research 2024: Results and Findings
The State of AI in Insights and Research 2024: Results and FindingsThe State of AI in Insights and Research 2024: Results and Findings
The State of AI in Insights and Research 2024: Results and FindingsRay Poynter
 
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17Celine George
 
ROLES IN A STAGE PRODUCTION in arts.pptx
ROLES IN A STAGE PRODUCTION in arts.pptxROLES IN A STAGE PRODUCTION in arts.pptx
ROLES IN A STAGE PRODUCTION in arts.pptxVanesaIglesias10
 
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptx
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptxINTRODUCTION TO CATHOLIC CHRISTOLOGY.pptx
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptxHumphrey A Beña
 
Narcotic and Non Narcotic Analgesic..pdf
Narcotic and Non Narcotic Analgesic..pdfNarcotic and Non Narcotic Analgesic..pdf
Narcotic and Non Narcotic Analgesic..pdfPrerana Jadhav
 
ANG SEKTOR NG agrikultura.pptx QUARTER 4
ANG SEKTOR NG agrikultura.pptx QUARTER 4ANG SEKTOR NG agrikultura.pptx QUARTER 4
ANG SEKTOR NG agrikultura.pptx QUARTER 4MiaBumagat1
 

Recently uploaded (20)

INCLUSIVE EDUCATION PRACTICES FOR TEACHERS AND TRAINERS.pptx
INCLUSIVE EDUCATION PRACTICES FOR TEACHERS AND TRAINERS.pptxINCLUSIVE EDUCATION PRACTICES FOR TEACHERS AND TRAINERS.pptx
INCLUSIVE EDUCATION PRACTICES FOR TEACHERS AND TRAINERS.pptx
 
Choosing the Right CBSE School A Comprehensive Guide for Parents
Choosing the Right CBSE School A Comprehensive Guide for ParentsChoosing the Right CBSE School A Comprehensive Guide for Parents
Choosing the Right CBSE School A Comprehensive Guide for Parents
 
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptx
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptxDIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptx
DIFFERENT BASKETRY IN THE PHILIPPINES PPT.pptx
 
Student Profile Sample - We help schools to connect the data they have, with ...
Student Profile Sample - We help schools to connect the data they have, with ...Student Profile Sample - We help schools to connect the data they have, with ...
Student Profile Sample - We help schools to connect the data they have, with ...
 
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdf
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdfVirtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdf
Virtual-Orientation-on-the-Administration-of-NATG12-NATG6-and-ELLNA.pdf
 
Transaction Management in Database Management System
Transaction Management in Database Management SystemTransaction Management in Database Management System
Transaction Management in Database Management System
 
4.18.24 Movement Legacies, Reflection, and Review.pptx
4.18.24 Movement Legacies, Reflection, and Review.pptx4.18.24 Movement Legacies, Reflection, and Review.pptx
4.18.24 Movement Legacies, Reflection, and Review.pptx
 
Production of Monoclonal Antibodies by Hybridoma Technology.pptx
Production of Monoclonal Antibodies by Hybridoma Technology.pptxProduction of Monoclonal Antibodies by Hybridoma Technology.pptx
Production of Monoclonal Antibodies by Hybridoma Technology.pptx
 
Influencing policy (training slides from Fast Track Impact)
Influencing policy (training slides from Fast Track Impact)Influencing policy (training slides from Fast Track Impact)
Influencing policy (training slides from Fast Track Impact)
 
Oppenheimer Film Discussion for Philosophy and Film
Oppenheimer Film Discussion for Philosophy and FilmOppenheimer Film Discussion for Philosophy and Film
Oppenheimer Film Discussion for Philosophy and Film
 
Using Grammatical Signals Suitable to Patterns of Idea Development
Using Grammatical Signals Suitable to Patterns of Idea DevelopmentUsing Grammatical Signals Suitable to Patterns of Idea Development
Using Grammatical Signals Suitable to Patterns of Idea Development
 
The State of AI in Insights and Research 2024: Results and Findings
The State of AI in Insights and Research 2024: Results and FindingsThe State of AI in Insights and Research 2024: Results and Findings
The State of AI in Insights and Research 2024: Results and Findings
 
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17
Incoming and Outgoing Shipments in 3 STEPS Using Odoo 17
 
Paradigm shift in nursing research by RS MEHTA
Paradigm shift in nursing research by RS MEHTAParadigm shift in nursing research by RS MEHTA
Paradigm shift in nursing research by RS MEHTA
 
ROLES IN A STAGE PRODUCTION in arts.pptx
ROLES IN A STAGE PRODUCTION in arts.pptxROLES IN A STAGE PRODUCTION in arts.pptx
ROLES IN A STAGE PRODUCTION in arts.pptx
 
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptx
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptxINTRODUCTION TO CATHOLIC CHRISTOLOGY.pptx
INTRODUCTION TO CATHOLIC CHRISTOLOGY.pptx
 
Narcotic and Non Narcotic Analgesic..pdf
Narcotic and Non Narcotic Analgesic..pdfNarcotic and Non Narcotic Analgesic..pdf
Narcotic and Non Narcotic Analgesic..pdf
 
Mattingly "AI & Prompt Design: Large Language Models"
Mattingly "AI & Prompt Design: Large Language Models"Mattingly "AI & Prompt Design: Large Language Models"
Mattingly "AI & Prompt Design: Large Language Models"
 
YOUVE_GOT_EMAIL_PRELIMS_EL_DORADO_2024.pptx
YOUVE_GOT_EMAIL_PRELIMS_EL_DORADO_2024.pptxYOUVE_GOT_EMAIL_PRELIMS_EL_DORADO_2024.pptx
YOUVE_GOT_EMAIL_PRELIMS_EL_DORADO_2024.pptx
 
ANG SEKTOR NG agrikultura.pptx QUARTER 4
ANG SEKTOR NG agrikultura.pptx QUARTER 4ANG SEKTOR NG agrikultura.pptx QUARTER 4
ANG SEKTOR NG agrikultura.pptx QUARTER 4
 

DNS Domain Name System Explained in 40 Characters

  • 2. A Presentation on Domain Name System Group Name :- G2 Group Members :- Gaurav Kumar Rohitash kumar Nitesh Kumar Rahul Baghla
  • 3.  Key terms  What is internet  How do they connect  History of the DNS  Introduction to the DNS  Components of the DNS  The namespace  The servers  The resolvers  Conclusion
  • 4.  The internet is a global system of interconnected computer networks . It is a network of networks that consists of millions of private and public , academic , business and government networks of local to global space that are linked by transmission media such as copper wires , fiber optic cables , wireless connections and other technologies .
  • 5.  A network of computers connected to each other is called internet and these computers needed to know which computer they were connecting to, so each computer was given a unique number – an IP (Internet Protocol) number. E.g. 121.245.078.2
  • 6.  There was the ARPANET’s HOSTS.TXT file  Each computer on the network retrieved a file called HOSTS.TXT  HOSTS.TXT mapped every ARPANET host’s name to its IP address.  The HOSTS.TXT file mapped numerical addresses to names.  Allows users to specify an IP address (e.g. 192.0.34.166) to use for a host name (e.g. www.google.com) without checking DNS.  Systems based on a hosts file have inherent limitations  The obvious requirement that every time a given computer's address changed, every computer that seeks to communicate with it would need an update to its hosts file.
  • 7.  Consistency  The network changed more quickly than the file was updated  Name collisions  No two hosts could have the same name  “Good” names quickly exhausted  There was no good method to prevent duplicate names  Human intervention was required  Traffic and load  The traffic generated by downloading the file became significant  Download time sometimes longer than update period  The model didn't scale well
  • 8.  ARPANET powers-that-were launched an investigation into replacement for HOSTS.TXT  Requirements:  Decentralized administration  With data updated locally, but available globally  A hierarchical name space  To guarantee unique names  Paul V. Mockapetris, American computer scientist and Internet pioneer, together with Jon Postel, invented the Internet Domain Name System (DNS).
  • 9.  The domain name system is usually used to translate a host name into an IP address and vice versa.  Domain names comprise a hierarchy so that names are unique, yet easy to remember.  DNS implements a distributed database to store domain name and address information for all public hosts on the Internet.  Defines a hierarchical namespace where each level of the namespace is separated by a “.”
  • 10. A fully qualified domain name is processed from right to left for its translation into the corresponding IP address. A fully qualified domain name can be made up of a top level domain (TLD), second level domain (SLD) and sub domains
  • 11.  The Name Space  The Servers  The Resolver
  • 12.  The name space is the structure of the DNS database  An inverted tree with the root node at the top  Each node has a label The root node "" top-level node second-level node third-level node top-level node second-level node second-level node third-level node top-level node second-level node third-level node second-level node
  • 13.  A domain name is the sequence of labels from a node to the root, separated by dots (“ . ”), read left to right
  • 14.
  • 15. in
  • 16.
  • 17.  One domain is a subdomain of another if its apex node is a descendant of the other’s apex node  More simply, one domain is a subdomain of another if its domain name ends in the other’s domain name  So abc.webs.com is a subdomain of  webs.com  com  webs.com is a subdomain of com
  • 18.  The Name Space  The Servers  The Resolver
  • 19.  Name servers store information about the name space in units called “zones”  The name servers that load a complete zone are said to “have authority for” or “be authoritative for” the zone  Usually, more than one name server are authoritative for the same zone  This ensures redundancy and spreads the load  Also, a single name server may be authoritative for many zones
  • 20. Two main types of servers  Local name servers:  Each ISP, company has local (default) name server  Host DNS query first goes to local name server  Authoritative name server:  For a host: stores that host’s IP address, name  Can perform name/address translation for that host’s name
  • 21.  Contacted by local name server that can not resolve name  Root name server:  contacts authoritative name server if name mapping not known  Gets mapping & returns mapping to local name server
  • 22.  The Name Space  The Servers  The Resolver
  • 23.  Name resolution is the process by which client and Local name servers cooperate to find data in the name space.  A Local name server receives a query from a client , looks for the answer in its database  If the answer isn’t in the database and the server isn’t authoritative for the answer, the answer must be looked up.
  • 24.  Let’s look at the resolution process step-by-step: Client Computer www.google.com
  • 25.  The client computers asks its Local name server, for www.google.com’s address Local Name Server What’s the IP address of www.google.com? Client Computer www.google.com
  • 26.  The Local name server asks a Root name server , for www.google.com’s address Local Name Server What’s the IP address of www.google.com? Client Computer www.google.com Root Server
  • 27.  The root server refers Local name server to the .com name servers. Local Name Server Client Computer www.google.com Root Server Here’s a list of the .com name servers. Ask one of them.
  • 28.  The Local name server asks .com name server, for www.google.com’s address What’s the IP address of www.google.com? Root Server Local Name Server .com Server Client Computer www.google.com
  • 29.  The com name server refers Local name server to the google.com name servers Here’s a list of the google.com name servers. Ask one of them. Root Server Local Name Server .com Server Client Computer www.google.com
  • 30.  The Local name server asks google.com name server, for www.google.com’s address What’s the IP address of www.google.com? Root Server Local Name Server Google.com Server .com Server Client Computer www.google.com
  • 31.  The google.com name server responds with www.google.com’s address Root Server Local Name Server Here’s the IP address for www.google.com Google.com Server .com Server Client Computer www.google.com
  • 32.  The Local name server responds to client computer with www.google.com’s address Here’s the IP address for www.google.com Root Server Local Name Server Google.com Server .com Server Client Computer www.google.com
  • 33.  After the previous query, the Local name server now knows:  The names and IP addresses of the com name servers  The names and IP addresses of the google.com name servers  The IP address of www.google.com  Let’s look at the resolution process again Client Computer www.google.com
  • 34.  The client computer asks its Local name server, for www.google.com’s address Root Server Local Name Server What’s the IP address of google.com? Google.com Server .com Server Client Computer www.google.com
  • 35.  The Local name server responds to client computer with www.google.com’s address Here’s the IP address for google.com Root Server Local Name Server Google.com Server .com Server Client Computer www.google.com
  • 36.  DNS is like a phone book for the Internet. If we know a person’s name but don’t know his mobile number, we can simply look it up in a phone book. DNS provides this same service to the Internet.  When we visit www.google.com in a browser, our computer uses DNS to retrieve the website’s IP address of 173.194.69.147 .