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| IP address and subnet mask |
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What is IP address?
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An IP address is a unique number that each devices have in Ethernet communication. A mechanism of Ethernet is similar to that of telephone. Each devices must have its own unique address in the Ethernet communication, in order to identify and communicate with each other. |
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A mechanism of IP address
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An IP address is written as four numbers separeted by dots, as shown above. It is shown in decimal (base 10) number to make it easier to read for us, but devices treat it as binary internally as shown below. |
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| IP:11000000 . 10101000 . 00000001 . 00000001 |
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An IP address is a 32-bit value (8-bit×4). Each 8-bit separeted by dots is expressed as a decimal (base 10) number, from 0 to 255. Therefore, there are 3.2 million patterns of IP address from "0.0.0.0" to "255.255.255.255".
However, the IP address actually used is called "private IP address" and it use the following address area that is devided by the universal rule.
<Pricate IP address>
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10. |
0. |
0. |
0 |
- |
10. |
255. |
255. |
255 |
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(Subnet: |
255. |
0. |
0. |
0) |
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Class A |
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172. |
16. |
0. |
0 |
- |
172. |
31. |
255. |
255 |
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(Subnet: |
255. |
255. |
0. |
0) |
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Class B |
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192. |
168. |
0. |
0 |
- |
192. |
168. |
255. |
255 |
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(Subnet: |
255. |
255. |
255. |
0) |
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Class C |
| * |
"0"(Zero) cannot be used in the last digit of IP address. |
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What is subnet mask?
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It is a numeric value used in conjunction with an IP address to manage devices by deviding into a small network when the network is too large to manage. |
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A mechanism of subnet mask
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Suppose an IP address is a phone number, a subnet mask separetes "area code" and "local number". When showing both an IP address and a subnet mask in binary and listing them as below, IP address's digits that correspond to the subnet mask's digits shown as "1" are treated as a "area code". |
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| E.g) |
| IP: |
192. |
168. |
3. |
1 |
| (=11000000.10101000.00000011.00000001) |
| Sub: |
255. |
255. |
255. |
0 |
| (=11111111.11111111.11111111.00000000) |
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| ←-----------------------------------------→←--------→ |
Network parts
(≒Area code)
Masked by "1" |
Host parts
(≒local number) |
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An area code is called "network address" and an local number is called "host address". Subnet mask devides the network by separating an IP address into those two parts. Devices that use same IP address can communicate each other directly. |
| Caution |
| If the enty node of "Pro-Server EX" does not connect to the other network, it will be no problem to use IP address (192.168.1.***) and subnet mask (255.255.255.0) . When setting the IP address of PC, set a fixed IP address (not "Obtain an IP address automatically"). |
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