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Correction #13431

closed

Incorrect count of /24 networks in a /5 CIDR block

Added by Abraham Samuel B. SANFO over 1 year ago. Updated over 1 year ago.

Status:
Resolved
Priority:
Normal
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Category:
General
Target version:
-
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Due date:
% Done:

100%

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Description

Page: https://docs.netgate.com/pfsense/en/latest/index.html

Feedback:

Good morning.
Reading "The pfSense documentation" I find an typos on the Table 4: CIDR subnet on P 243 table since the CIDR mask /5.
With a /5 I think the number of /24 subnets is: 2^(32 - 5 - 8) = 524288 and not 1,048,576 like you write.

I just apply the formula for the number of subnetwork: 2^(32 - N - M)

where 32 - N - M is the length of the subnetwork part:
32: the total length of an ipv4 address
N: the length of the network id; in our case 5 bits
M the length of the host id; we use a /24 in the book so it remains 8 bits for the host id.


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pfSenseDoc.png (109 KB) pfSenseDoc.png A capture Abraham Samuel B. SANFO, 08/19/2022 11:27 AM
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