The Internet Address

What is IP address?

Ø  A number that uniquely identifies each computer or device connected to the Internet.

Ø  IP addresses are also referred to as IP numbers and Internet addresses.

Ø  IP address sometimes is called a dotted decimal number or dotted quad.

  

and how about IP structure?

Ø  IP addresses usually consists of four groups of number each separated by a period.

Ø  The number in each group is between 0 and 255.

Ø  It is 32 bit long ,each group is 8 bits long

Ø  Commonly written in decimal.

Ø  Written, for example, 128.35.0.72

ØThese four sections represent the machine itself and the network it is on

ØThe network portion is assigned.

ØThe host section is determined by the network administrator 

There are 2 versions of Internet Protocol are in use;

• IP V4
• IP V6

• IPv4 
• an address consists of 32 bits which limits the address space to 4294967296 (232) possible unique addresses.

• IPv6
• The address size was increased from 32 to 128 bits or 16 octets.
• Provides the potential for a maximum of 2128, or about 3.403×1038 unique addresses.

Domain name and IP address

• People prefer to use easy-to-remember names instead of IP addresses
• Domain names (a part of the URL) are alphanumeric names for IP addresses.

• e.g., neon.ece.utoronto.ca, www.google.com, ietf.org

• The domain name system (DNS) is an Internet-wide distributed database that translates

         between domain names and  IP addresses

•How important is DNS?

  Imagine what happens when the local DNS server is down.

Domain name

•The text version of an IP address

Generally,

•First portion of each IP address identifies the network

•Last portion identifies the specific computer.

 

Domain Name System

 IP address and domain name allocation requires central administration to avoid duplication 

 Previously administered by U.S. government contract (NSI)

 In 1998, technical coordination assigned to ICANN (Internet Corporation for Assigned Names and Numbers).

–ICANN is the official organization that coordinates domain names on the World Wide Web. ICANN is also responsible for approving or denying new domain extensions.

Top-level domains(TLDs)

•The first-level set of domain names are the top-level domains (TLDs).

•Three types of top-level domains:

–Organizational: 3-character code indicates the function of the organization

•Used primarily within the US

•Examples: gov, mil, edu, org, com, net

–Geographical: 2-character country or region code

•Examples: us, va, jp, de

•

–Reverse domains: A special domain (in-addr.arpa) used for IP address-to-name mapping

There are more than 200 top-level domains.

Generic Top-level domains (GTLD)

•A generic top-level domain (gTLD) is one of the categories of top-level domains (TLDs) maintained by the Internet Assigned Numbers Authority (IANA) for use in the Domain Name System of the Internet.