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The number of available IP addresses theoretically is 255x255x255x255 or about 4 billion more to be distributed to all users worldwide Internet network.The division of these classes are intended to facilitate the allocation of IP addresses, both for the host / network or for certain specific purposes. 


IP addresses can be separated into two parts, namely the network (net ID) and the host (host ID). Net ID plays a role in the identification of a network from another network, while the host ID serves to identify a host within a network. So, all hosts that are connected in the same network have the same net ID. Some of the bits of the early part of the IP Address is the network bits / network number, while the rest is for the host. The dividing line between the network and hosts are not fixed, depending on the class network. IP addresses are divided into five classes, namely class A, class B, class C, class D and class E. 


Differences of each class is the size and number. For example class A IP network is used by few but the number of hosts that can be accommodated by each network is very large. Class D and E are not used in general, a class D is used for network multicast and class E for experimental . Internet Protocol software to determine the division of this class type by examining the first few bits of the IP Address. The determination of this class is done in the following ways: 


The first bit IP address class A is 0, with a length of 8 bits of the net ID and host ID 24 bits long. So the first byte of the IP address class A has a range of 0-127.So in class A there are 127 networks with each network can accommodate about 16 million hosts (255x255x255). 
IP addresses are given for the class A network with a very large number of hosts, the IP of this class can be depicted in the image below: 

IP address class A 
Two bits of a class B IP address is always set 10, so the first byte is always worth between 128-191. Network ID is 16 bits first and the remaining 16 bits are the host ID so if there is a computer having IP address 167.205.26.161, the network ID and host ID = 167 205 = 26 161. At. Class B IP address has IP range of 128.0.xxx.xxx to 191.155.xxx.xxx, which amount to 65,255 hosts per network with a number of network hosts 255 x 255 or approximately 65 thousand hosts. 
  


Class B IP address 
Class C IP address originally used for small sized networks such as LANs. The first three bits of a class C IP address is always set 111. Network ID consists of 24 bits and 8 bits of remaining host ID so it can be formed about 2 million networks with each network has 256 hosts. 
  


Class C IP address 
Class C IP address used for multicasting. The first four bits of a class C IP address is always set to 1110 so that the first byte ranges between 224-247, while the next bit is set as required using the multicast group IP address.Multicasting is not known term in the network ID and host ID. 
Class E IP addresses are not intended for public use. The first 4-bit IP address class of 1111 is set so that the first byte range between 248-255. 


In addition the term is also known as Network Prefix, which is used to designate the IP address prefix is  network with a slash "/" followed by numbers that indicate the network prefix length in bits. For example to designate a class B network 167.205/16 167.205.xxx.xxx used writing. This is item 16 bits for the network prefix length of class B. 


Configure TCP / IP 
Implementation of TCP / IP in Windows 98 includes a standard protocol TCP / IP, compatible with 
TCP / IP-based networks. Standard protocol TCP / IP including: 
1. Internet Protocol, 
2. Transmission Control Protocol (TCP), 
3. Internet Control Message Protocol (ICMP), 
4. Address Resolusion Protocol (ARP), 
5. User Datagram Protocol (UDP). 
TCP / IP must be configured before the first order to "communicate" in the network 
computer. Each computer has a network card installed requires an IP address and subnet 
mask. IP addresses must be unique (different from the other computer), the subnet mask is used to 
distinguish the network ID of the host ID. 
Provide IP Address 
IP address and subnet mask can be assigned automatically using Dynamic Host 
Configuration Protocol (DHCP) or manually condition. 

Figure 2.4. IP address in TCP / IP properties

The procedure is done to fill in the IP address: 
1. Open the Control Panel and double-click the Network icon. 
2. On the Configuration tab, click TCP / IP on the list for network cards that have been 
installed. 
3. Click Properties. 
4. In the IP Address tab, there are 2 options: 
* Obtain an IP address automatically 
IP addresses will be obtained through DHCP facility. DHCP function to assign IP addresses 
automatically on computers that use TCP / IP. DHCP works with relation 
client-server, where the DHCP server provides a group of IP addresses that can be given 
the DHCP client. In providing this IP address, DHCP lends an IP address only 
them. So this last provision of the IP address dynamically. 
* Specify an IP address 
IP address and subnet mask manually filled. 
5. Click OK. 
6. If necessary re-entry into the dialog box TCP / IP Properties, click the Gateway tab, 
enter the server address. 
7. Click OK. 
8. If it is necessary to enable the Windows Internet Naming Service (WINS) server, re- 
into the dialog box TCP / IP Properties, click the WINS Configuration tab, and click Enable 
WINS Resolution and enter the server address numbers. 
9. If it is necessary to activate the domain name system (DNS), back in the box 
dialogue TCP / IP Properties, click the DNS Configuration tab, click Enable DNS, enter the number 
server address. 
10. Click OK.