Dns domain name server
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DNS Domain Name Server. Group: 4. Group Members Names. Bilal Virk Sehrish Javed Maryam Azhar Rehan Ali. DNS. introduction. DNS (Domain Name Server). Brief Presentation. We could spend all Day. Unsure about level of technical expertise. Stop me at any point if you have a query.

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DNS Domain Name Server

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Dns domain name server

DNSDomain Name Server

Group: 4


Group members names

Group Members Names

  • Bilal Virk

  • Sehrish Javed

  • Maryam Azhar

  • Rehan Ali


Dns domain name server

DNS

introduction


Dns domain name server1

DNS (Domain Name Server)

  • Brief Presentation.

  • We could spend all Day.

  • Unsure about level of technical expertise.

  • Stop me at any point if you have a query.


What this talk is about

What This Talk Is About!

  • What Is DNS?

  • Why DNS Is Needed?

  • History of DNS.

  • Hierarchy of DNS.

  • How Dose It Works?

  • What Are Zones?


What is dns

What is DNS?

  • Computers use IP addresses for Internet Traffic.

  • IP Addresses Are hard To remember

  • So, We use Names Instead.


What is dns cont

What is DNS? (Cont…)

  • The domain name system is usually used to

    translate a host name into an IP address .

  • Domain names comprise a hierarchy so that

    names are unique, yet easy to remember.

    So , We Can Say

    DNS is used for name to IP resolution

    &

    IP to name resolution.


History of dns

History of DNS

Host File System


Old solution host txt

Old Solution (host.txt)

  • Back in the early 80’s when the internet was called ARPANET, consisted of few hundred computers, servers on MIT university Campus.

  • Held A file that listed the names and IP address of those few computers.

  • That File was Named As HOST.TXT.

  • When a new host was attached to ARPANET it needed the NAMES and IPs of others computers over ARPANET for that reason it would just contact MIT server and download the latest Host file.


Old solution host txt1

128.4.13.9 SPARKY

4.98.133.7 UCB-MAILHOST

200.10.194.33 FTPHOST

Old Solution (host.txt)

  • A centrally-maintained file, distributed to all hosts on the Internet

  • This feature still exists

    • /etc/hosts [Linux]

    • c:\windows\system32\drivers\etc\hosts [Windows]


Hosts txt doesn t scale

Hosts.txt Doesn't Scale

  • Huge file

  • Needs frequent copying to ALL hosts

  • Consistency

  • Always out-of-date

  • Name uniqueness

  • Single point of administration


Hierarchy of dns

Hierarchy of DNS

Domain Levels


Hierarchy of dns1

Hierarchy of DNS

We Offten Forget This Little Thing which has a huge role in DNS

Root Domain

TOP level Domain

2nd Level Domain

Host ,PC

www

.Yahoo

.Com

.

www.Yahoo.Com.


Hierarchy of dns2

Hierarchy of DNS

. (root)

uk

com

net

org

co.uk

Yahoo.com

Iso.net

isoc.org

nsrc.org

www.Yahoo.com

ftp.Iso.net

www.isoc.org

tiscali.co.uk


Hierarchy of dns3

Hierarchy of DNS

. (root)

uk

com

net

org

co.uk

Yahoo.com

Iso.net

isoc.org

nsrc.org

www.Yahoo.com

ftp.Iso.net

www.isoc.org

tiscali.co.uk


Example www yahoo com

www.yahoo.com

rootserver

referral to ‘.com' DNS Servers

www.yahoo.com

.com

server

referral to ‘yahoo.com’

DNS Server

www.yahoo.com

ww.yahoo.com

server

Answer: 212.74.101.10

Example : www.yahoo.com


Point to ponder

Point To Ponder

Root Address


Root address

Root Address

  • In the Previous Slide We saw

    • Root Provided the Address for Com

    • Com Provided the Address for Yahoo

    • Yahoo Provided the Address for www.yahoo.com

      But What or Who Provided The Address For .Root Server?


Answer

Answer

  • There is a Term called

    “ROOT HINTS”

    Root Hint: On the DNS server there is a file which contains the ROOT SERVER ADDRESS which Holds the address for the root servers. Thus, It Comes For the Root Server Address File

    Amazing Fact:

    There Are Only 13 Root Servers on the Whole Planet.


Non authoritative dns

Application

e.g. web browser

Authoritative

DNS

Caching ISP

/ DNS

Resolver

Non-Authoritative DNS.

Request For IP Address

IP Address Found


Authoritative dns

Application

e.g. web browser

Authoritative

DNS

Caching ISP

/ DNS

Resolver

Authoritative DNS.

Request For IP Address

IP Address Not Found

IP Address Found


What is a resource record

What is a resource record?

  • A domain contains resource records

  • Resource records are analogous to files

  • Classified into types

  • Some of the important types are, A,CNAME and MX


Dns domain name server

  • The “A” Record

  • The “Address” record

  • One or more normally defines a host

  • Contains an IPv4 Address (the address computers use to uniquely identify each other on the internet)

  • Eg. The record:

  • wwwA203.18.56.31

  • In the yahoo.com domain, defines the host uniquely identifiable as “www.yahoo.com.” to be reachable at the IPv4 Address 203.18.56.31


Dns domain name server

  • The “CNAME” Record

  • A CNAME defines an alias

  • Assign multiple names against single IP Adress

  • Eg. The record:

  • searchCNAMEwww.yahoo.com.

  • In the yahoo.com domain, defines the name uniquely identifiable as “search.yahoo.com” to be and alias to “www.yahoo.com”


Dns domain name server

  • The “MX” Record

  • An MX record defines the mail servers for a particular domain

  • Mail eXchange records hold the name of hosts, and their priorities, able to deliver mail for the domain.

  • Eg. The record:

  • ausregistry.com.auMX10mail

  • In the ausregistry.com.au domain, defines the host mail to be the priority 10 mail server for the “ausregistry.com.au” domain


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