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| | A '''Netmask''' is a 32-bit "mask" used to divide an IP address into subnets and specify the network's available hosts. In a netmask, two bits are always automatically assigned. For example, in 255.255.225.0, "0" is the assigned network address. In 255.255.255.255, "255" is the assigned broadcast address. The 0 and 255 are always assigned and cannot be used. | | A '''Netmask''' is a 32-bit "mask" used to divide an IP address into subnets and specify the network's available hosts. In a netmask, two bits are always automatically assigned. For example, in 255.255.225.0, "0" is the assigned network address. In 255.255.255.255, "255" is the assigned broadcast address. The 0 and 255 are always assigned and cannot be used. |
| | | | |
| − | Netmask defines how "large" a network is or if you're configuring a rule that requires an IP address and a Netmask, the Netmask will signify to what portion or range of the Network the rule will apply to: | + | Netmask defines how "large" a network is or if you're configuring a rule that requires an IP address and a Netmask, the Netmask will signify to what range of the Network the rule will apply to: |
| | | | |
| − | {| class="wikitable"
| + | <table class="nd-othertables"> |
| − | |+
| + | <tr> |
| − | ! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | IP
| + | <th style="width: 200px">IP</th> |
| − | ! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
| + | <th style="width: 200px">NETMASK</th> |
| − | ! style="width: 400px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | DESCRIPTION
| + | <th style="width: 400px">DESCRIPTION</th> |
| − | |-
| + | </tr> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.161
| + | <tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.255
| + | <td>192.168.55.161</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Only applies to 192.168.55.161'''
| + | <td>255.255.255.255</td> |
| − | |-
| + | <td>Only applies to 192.168.55.161</td> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.0
| + | </tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.0
| + | <tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Applies to IPs in the 192.168.55.0 - 192.168.55.255 range
| + | <td>192.168.55.0</td> |
| − | |-
| + | <td>255.255.255.0</td> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.240
| + | <td>Applies to IPs in the 192.168.55.0 - 192.168.55.255 range</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.240
| + | </tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.240 - 192.168.55.255
| + | <tr> |
| − | |-
| + | <td>192.168.55.240</td> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.161
| + | <td>255.255.255.240</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.0
| + | <td>192.168.55.240 - 192.168.55.255</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.0 - 192.168.55.255
| + | </tr> |
| − | |-
| + | <tr> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.0.0
| + | <td>192.168.55.161</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.0.0
| + | <td>255.255.255.0</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.0.0 - 192.168.255.255
| + | <td>192.168.55.0 - 192.168.55.255</td> |
| − | |-
| + | </tr> |
| − | |}
| + | <tr> |
| | + | <td>192.168.0.0</td> |
| | + | <td>255.255.0.0</td> |
| | + | <td>192.168.0.0 - 192.168.255.255</td> |
| | + | </tr> |
| | + | </table> |
| | | | |
| | | | |
| | Sometimes you will see that a Netmask is defined by one number, e.g., '''24'''. This number is the length of the Netmask in bits: | | Sometimes you will see that a Netmask is defined by one number, e.g., '''24'''. This number is the length of the Netmask in bits: |
| | | | |
| − | {| class="wikitable"
| + | <table class="nd-othertables"> |
| − | |+
| + | <tr> |
| − | ! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
| + | <th style="width: 200px">NETMASK</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255
| + | <th style="width: 100px">255</th> |
| − | |-
| + | </tr> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Netmask length
| + | <tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 8
| + | <td>Netmask length</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
| + | <td>8</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 24
| + | <td>16</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 32
| + | <td>24</td> |
| − | |-
| + | <td>32</td> |
| − | |}
| + | </tr> |
| | + | </table> |
| | | | |
| | | | |
| | So, for example, a Netmask that is 24-bits long is '''255.255.255.0''': | | So, for example, a Netmask that is 24-bits long is '''255.255.255.0''': |
| | | | |
| − | {| class="wikitable"
| + | <table class="nd-othertables"> |
| − | |+
| + | <tr> |
| − | ! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
| + | <th style="width: 200px">NETMASK</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 0
| + | <th style="width: 100px">0</th> |
| − | |-
| + | </tr> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Netmask length
| + | <tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 8
| + | <td>Netmask length</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
| + | <td>8</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 24
| + | <td>16</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
| + | <td>24</td> |
| − | |-
| + | <td>-</td> |
| − | |}
| + | </tr> |
| | + | </table> |
| | | | |
| | | | |
| | A Netmask that is 16-bits long is '''255.255.0.0''': | | A Netmask that is 16-bits long is '''255.255.0.0''': |
| | | | |
| − | {| class="wikitable"
| + | <table class="nd-othertables"> |
| − | |+
| + | <tr> |
| − | ! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
| + | <th style="width: 200px">NETMASK</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
| + | <th style="width: 100px">255.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 0.
| + | <th style="width: 100px">0.</th> |
| − | ! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 0
| + | <th style="width: 100px">0</th> |
| − | |-
| + | </tr> |
| − | ! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Netmask length
| + | <tr> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 8
| + | <td>Netmask length</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
| + | <td>8</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
| + | <td>16</td> |
| − | | style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
| + | <td>-</td> |
| − | |-
| + | <td>-</td> |
| − | |}
| + | </tr> |
| | + | </table> |
| | | | |
| | And so on. | | And so on. |
| | + | |
| | + | [[Category:Networking]] |
