This is a video created to help people understand the basics of IPv4 Addressing and how it works. Script: This video explains what IP addressing is and why it is used. For computers to communicate with each other through a network it is necessary to be able to identify specific computers over a network. An example of an IP address is 195.195.92.161 this translates to 11000011.11000011.01011100.10100001 in binary. These numbers may look complicated but when explained they are very simple The use of IP addressing is no different to the use of a phone number. Phone numbers are used as a way of communicating with specific people. Phone numbers use both and area code and identifier. Ip addressing uses a similar method of identification. It uses a network number and an identifier number. For example if we have 3 separate networks all with 5 computers. There would be 3 network different network address's . 1.1, 1.2, 1.3, 2.1 etc... IP addresses are in total 32 bits long. 11000011110000110101110010100001 Each string of 32 bits is then split into 4 equal parts of 8 bits 11000011.11000011.01011100.10100001 These four strings of 8 bits are then converted into decimal numbers for ease of human use. 195.195.92.161 This IP address would then be split up into two parts, one is used to identify the network and one is then used to identify a computer hosted on that network. The part of the IP address used to identify varies depending on the CLASS. There are 5 classes of IP address, A,B,C,D and E. A, B, and C are used for assigning IP addresses Classes D and E are reserved for special use. D is used for multicasting E is reserved for experimentation A, B and C are the we'll be looking at. Now the difference between these three types of IP address is how it is split between network and host. Class A addresses use the first part of the IP address only when identifying a network. XXXXXXXX.ZZZZZZZZ.ZZZZZZZZ.ZZZZZZZZ X = Network part Z= Host part In the network part of a class A address the leading bit is a 0 allowing the last 7 bits to be used as network identifiers. This allows Class A to have 2^7 networks (128) There are 24 bits left in the host part of a class A IP address allowing them to be used to identify hosts within a network. This means each network on this system could have 2^24 hosts (16,777,216) Class B addresses use the first part of the IP address only when identifying a network. XXXXXXXX.XXXXXXXX.ZZZZZZZZ.ZZZZZZZZ X = Network part Z= Host part In the network part of a class A address the leading bits are 10 allowing the last 14 bits to be used as network identifiers. This allows Class A to have 2^14 networks (16,384) There are 16 bits left in the host part of a class A IP address allowing them to be used to identify hosts within a network. This means each network on this system could have 2^16 hosts (65,536) Class C addresses use the first part of the IP address only when identifying a network. XXXXXXXX.XXXXXXXX.XXXXXXXX.ZZZZZZZZ X = Network part Z= Host part In the network part of a class A address the leading bits are 110 allowing the last 21 bits to be used as network identifiers. This allows Class A to have 2^21 networks (2,097,152) There are 8 bits left in the host part of a class A IP address allowing them to be used to identify hosts within a network. This means each network on this system could have 2^8 hosts (256)

• published: 10 Jan 2013
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