Internet Technology Lectures URL-DNS Lecturer: Saman M. Almufti / Kurdistan Region, Nawroz University facebook: https://www.facebook.com/saman.malmufti YouTube link: https://youtu.be/pOx04uODo5o

1. Internet Technology
Saman M. Almufti
Lecture 5

3. • The domain name system (DNS) is
a Server represents a large database
used for transforming alphanumeric
domain names into numeric IP
addresses. A decentralized process,
name resolution generally takes place
on DNS servers’ networks distributed
throughout the world. Every internet
address you enter into your web
browser’s search bar is then forwarded
by your router to a DNS server. This
server then dissolves the domain name
into a numeric sequence and returns a
corresponding IP address.
• DNS is used in TCP/IP Application layer

4. In order to understand the process behind the DNS resolution, it’s important to learn
about the different hardware components a DNS query must pass between. For the web
browser, the DNS lookup occurs “ behind the scenes” and requires no interaction from
the user’s computer apart from the initial request.
Web
Browser

5. Root
.com .net.org.edu
Nawroz.edu Google.com Yahoo.com
Recursor /
Resolver
• Computer’s DNS cache: If the DNS records are found in
your computer’s DNS cache, then the rest of the DNS
lookup is skipped and you will be taken directly the
requested website
• Resolving nameserver: Typically this is your Internet
services provider’s (ISP) server
• Root Server: The authoritative name servers that serve
the DNS root zone, commonly known as the “root
servers”, are a network of hundreds of servers in many
countries around the world. They are configured in the
DNS root zone as 13 named authorities
• Top Level Domain (TLD):TLD refers to the last part of a
domain name. The most common TLDs include .com,
.net, org, and .info. Country code TLDs represent specific
geographic locations. For example: .iq represents Iraq.
• Alternative Nameserver: This is the part of a domain
name which comes right before the TLD
Computer
Browser

6. IP Address

8. http://journal.qubahan.com/index.php/qaj
URL
What’s in a name (URLs)
 URL = Uniform Resource Locator
 Contains three parts:
 Protocol (http, ftp, etc.)
 Server name (Domain Name)
 File name, including path
Protocol for reading
Server name – extension tells type of server
File name and path*
DomainSub Domain extension
a website URL is the location of a specific website, page, or file on the
Internet.

9. IP Address