About IP Addresses

On the Internet, you are nothing but an IP address!

What is an IP Address? An Internet Protocol (IP) address is a numeric identifier that includes information about how to reach a network location through the Internet routing system.

IPv4 and IPv6 Internet Protocol version 4 Internet Protocol version 6 32-bit* number128-bit* number Dotted Decimal Notation: Hexadecimal Notation: 2001:DB8::/32 4 billion network addresses 16 billion-billion network addresses * bit = binary digit

IP Addresses Are: Necessary for Internet routing A finite common resource Not dependent upon the DNS

Not owned by address users –Not property –Cannot be bought, sold, traded… –Provided on a temporary basis –Returned to registry or provider when no longer required IP Addresses Are:

How does an IP address make the Internet work?

What is Routing? Routing is the act of moving information across an internetwork from a source to a destination.

Each computer communicates with the other computers on its network, creating a total of 15 connections. Six computers need to communicate with each other. On a larger network, individual connections become unmanageable. Point-to-Point Networking

Network Instead, the computers can connect to a single router. Router

Interconnected Networks Each network can link to other networks via its router Each segment receives IP addresses

Administrative Grouping Registries provide Internet number resources to help divide internetworks into interconnected, autonomous groups of devices AS 1234 AS 2345 AS 3456 Groups of devices with a single, clearly defined routing policy may be assigned an Autonomous System Number (ASN).

Traffic /24 Announce /24 Internet Address Routing Internetwork Routing Table 4.128/ / / /16 … Internetwork Routing Table 4.128/ / / / /24 … /24 1.The network announces an IP address range. 2.The range is added to a specific table within a router. 3.The router can redistribute information to devices within the network. The Internet

Internet Address Routing Traffic Routing Table / /25 Local Router /24 1.Traffic enters the network according to the routing table. 2.The local router directs traffic to the appropriate device according to its own routing table.

Global Internet Routing Network Internetwork Routing Table 4.128/ / / /16 … With a coordinated numbering system, you can build a network of networks.

What is the Domain Name System (DNS)? The Domain Name System (DNS) is a means of storing and retrieving information about host names and IP addresses in a distributed database.

IP Addresses Are Not Domain Names IP AddressDomain Name Computer-friendlyPeople-friendly IdentifierReference Unique number identifies computer on Internet Host name mapped to an IP address Used for routingNot used for routing

2001:0C00:8888:: My Computerwww. cernet.cn 2001:0400:: :0400:: Using Domain Names The Internet DNS 1. My Computer asks the DNS where to find 2. The DNS provides the IPv4 or IPv6 address for the requested URL. 3. My Computer queries the appropriate server for the IP address provided by the DNS.

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