Difference between revisions of "What is a Netmask?"

From Teltonika Networks Wiki
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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 portion or range of the Network the rule will apply to:
  
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{| class="wikitable"
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<table class="nd-othertables">
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|+
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    <tr>
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! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | IP
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        <th style="width: 200px">IP</th>
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! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
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      <th style="width: 200px">NETMASK</th>
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! style="width: 400px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | DESCRIPTION
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      <th style="width: 400px">DESCRIPTION</th>
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|-
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    </tr>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.161
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    <tr>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.255
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      <td>192.168.55.161</td>
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| 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'''
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      <td>255.255.255.255</td>
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|-
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      <td>Only applies to 192.168.55.161'''</td>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.0
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    </tr>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.0
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    <tr>
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| 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
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      <td>192.168.55.0</td>
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|-
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      <td>255.255.255.0</td>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.240
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      <td>Applies to IPs in the 192.168.55.0 - 192.168.55.255 range</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.240
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    </tr>
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| 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
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    <tr>
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|-
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    <td>192.168.55.240</td>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.55.161
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        <td>255.255.255.240</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.255.0
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        <td>192.168.55.240 - 192.168.55.255</td>
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| 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
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    </tr>
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|-
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    <tr>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 192.168.0.0
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    <td>192.168.55.161</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 255.255.0.0
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        <td>255.255.255.0</td>
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| 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
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        <td>192.168.55.0 - 192.168.55.255</td>
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|-
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    </tr>
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|}
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    <tr>
 +
    <td>192.168.0.0</td>
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        <td>255.255.0.0</td>
 +
        <td>192.168.0.0 - 192.168.255.255</td>
 +
    </tr>
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</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:
  
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{| class="wikitable"
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<table class="nd-othertables">
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|+
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    <tr>
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! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
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        <th style="width: 200px">NETMASK</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255
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      <th style="width: 100px">255</th>
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|-
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    </tr>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Netmask length
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    <tr>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 8
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      <td>Netmask length</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
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      <td>8</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 24
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      <td>16</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 32
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      <td>24</td>
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|-
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      <td>32</td>
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|}
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    </tr>
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</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''':
  
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{| class="wikitable"
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<table class="nd-othertables">
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|+
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    <tr>
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! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
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        <th style="width: 200px">NETMASK</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <th style="width: 100px">255.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 0
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      <th style="width: 100px">0</th>
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|-
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    </tr>
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! style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | Netmask length
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    <tr>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 8
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      <td>Netmask length</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
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      <td>8</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 24
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      <td>16</td>
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| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
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      <td>24</td>
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|-
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      <td>-</td>
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|}
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    </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''':
  
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{| class="wikitable"
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<table class="nd-othertables">
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|+
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    <tr>
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! style="width: 200px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | NETMASK
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        <th style="width: 200px">NETMASK</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 255.
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      <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.
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      <th style="width: 100px">0.</th>
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! style="width: 100px; border: 1px solid white; border-bottom: 2px solid #0054A6; background: white; color: #0054A6; text-align: left;" | 0
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      <th style="width: 100px">0</th>
−
|-
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    </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
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      <td>Netmask length</td>
−
| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | 16
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      <td>8</td>
−
| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
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      <td>16</td>
−
| style="border: 1px solid white; border-bottom: 2px solid #E8E8E8; text-align: left; vertical-align: top; background: white;" | -
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      <td>-</td>
−
|-
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      <td>-</td>
−
|}
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    </tr>
 +
</table>
  
 
And so on.
 
And so on.

Revision as of 16:54, 19 December 2018

Main Page > FAQ > Networking > What is a Netmask?

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:

IP NETMASK DESCRIPTION
192.168.55.161 255.255.255.255 Only applies to 192.168.55.161
192.168.55.0 255.255.255.0 Applies to IPs in the 192.168.55.0 - 192.168.55.255 range
192.168.55.240 255.255.255.240 192.168.55.240 - 192.168.55.255
192.168.55.161 255.255.255.0 192.168.55.0 - 192.168.55.255
192.168.0.0 255.255.0.0 192.168.0.0 - 192.168.255.255


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:

NETMASK 255. 255. 255. 255
Netmask length 8 16 24 32


So, for example, a Netmask that is 24-bits long is 255.255.255.0:

NETMASK 255. 255. 255. 0
Netmask length 8 16 24 -


A Netmask that is 16-bits long is 255.255.0.0:

NETMASK 255. 255. 0. 0
Netmask length 8 16 - -

And so on.

Retrieved from "https://wiki.teltonika-networks.com/index.php?title=What_is_a_Netmask%3F&oldid=25705"