NET323 D:

NETWORKS PROTOCOLS

Lab # 8: DNS (Domain Name System) Networks and Communication

Systems Department

TA. Anfal AlHazzaa

1

Lab Objectives 2

To understand how DNS works

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Lab Content

Introduction to Application Layer

What is Server?

What is Client?

What is DNS (Domain Name System)?

Scenario # 1 (Accessing Web server without DNS)

Scenario # 2 (Accessing Web server with DNS)

3

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Introduction to Application layer

4

There are several applications in the application layer

of the Internet model that follow the client/server

paradigm.

The client/server programs can be divided into two

categories:

Application that directly used by the user, such as e-mail,

Application that support other application programs.

The Domain Name System (DNS) is a supporting

program that is used by other programs such as e-mail.

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

What is Server?

5

A server is a computer program or a machine capable

of accepting requests from clients and responding to

them.

Typical computing servers are database servers, file

servers, mail servers, print servers, web servers, game

servers and DNS server.

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

What is Client? 6

A client is a piece of computer hardware or software

that accesses a service made available by a server

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

What is DNS (Domain Name System)?

7

DNS translates Internet domain and host names to IP

addresses. DNS automatically converts the names we

type in our Web browser address bar to the IP addresses

of Web servers hosting those sites.

DNS is a supporting program that is used by other

programs such as e-mail and web browser

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

How DNS works? 8

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Scenario # 1: Accessing Web server without DNS

9

1. Create a simple LAN contains two clients and web

server

2. Access the web server using the IP address of the

web server

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

1. Open The Packet tracer

2. Add two PCs and one Server-PT to your workspace

3. Rename them and set their IPs as follows:

Step 1 )Creating the network(

10

Device Type Device name IP Mask

PC Client 1 192.168.1.1 255.255.255.0

PC Client 2 192.168.1.2 255.255.255.0

Server Web Server 192.168.1.253 255.255.255.0

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 1 )Creating the network( cont.

11

4. Drag Switch-PT to the workspace

5. Using Copper Straight-through cable connect the

end devices to the switch as follows:

Device name Switch ports

Client 1 Fast Ethernet 0/1

Client 2 Fast Ethernet 1/1

Web Server Fast Ethernet 2/1

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Click on the Web Server config tab choose HTTP

Step 2 ) Configuring the web server( 12

1

2

3. Turn the

HTTP and

HTTPS on

The content of the home

page

To go to previous or next page

To add new page

The page name

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 3 ) Accessing the web server from client 1(

13

Click on client 1 desktop tab web browser

2

1

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 3 )Accessing the web server from client 1( cont.

14

To access the webpages

which stored in the web

server type the IP

address of the web server

click on “GO” button”

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Scenario # 2: Accessing Web server with DNS

15

1. Create a simple LAN contains two client , web server

and DNS server

2. Use DNS server to access the web server

3. Capture and analyze DNS request and replay

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

1. Add server-PT to the previous topology

2. Rename the server and assign its IP as follows

4. Using Copper Straight-through cable connect the DNS server to the switch as follows:

Step 1 )Creating the network(

16

Device Type PC name IP Mask

Server DNS server 192.168.1.252 255.255.255.0

Device name Switch ports

DNS Server Fast Ethernet 3/1

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Click on the DNS Server config tab choose DNS

Step 2 ( Configuring DNS server )

17 1

2

3. Turn on the

DNS

5. Choose “A record”

4. Type the

domain name of

the web server

6. Type the IP address of

the web server and then

click on “Add” button

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 3 ( Configuring DNS on the end devices)

18

Click on Client 1 desktop tab IP configuration

Repeat the same configuration on all end devices

Type the IP of the DNS

server

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 4 ( Accessing the web server from client 1)

19

Click on Client 1 desktop tab web browser

2

1

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 4 ( Accessing the web server from client 1) cont.

20

To access the webpages

which stored in the web

server type the domain

name of the web server

click on “GO” button”

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

Step 5 (Capturing and analyzing DNS message)

21

1. Switch to Simulation mode.

2. In the Simulation Panel, change Edit Filters to display only DNS and HTTP.

3. Click Client 1 and click the Desktop tab Web Browser.

4. In the URL field, enter pnu.edu.sa and click Go.

5. Envelopes (PDUs) will appear in the simulation

window.

6. Minimize, but do not close, the Client 1configuration window.

7. Run the simulation.

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa

References

22

Cisco Packet Tracer Help

“Data Communication and Networking”, by Behrouz A Forouzan, McGraw

Hill, 2006 .

Server (computing). (2015, November 13). Retrieved 2015, from

https://en.wikipedia.org/wiki/Server_(computing)

Client (computing). (2015, September 11). Retrieved 2015, from

https://en.wikipedia.org/wiki/Client_(computing)

Domain Name System (DNS). (n.d.). Retrieved 2015, from

http://bmet.wikia.com/wiki/Domain_Name_System_(DNS)

Networks and Communication Systems Department – Prepared By: TA. Anfal AlHazzaa