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Knowledgebase: Product Manual > Appendices
Cipafilter Documentation - Appendix I: Dot notation to CIDR notation translation table
Posted by Jim Giseburt, Last modified by Landon Ritchie on 26 February 2018 10:58 AM

This walk through applies to Cipafilter's on version 7.0 and above and cover's CIDR notation as a way of delineating IP address ranges in a notation that proceeds an IP address as used in the Web Reports, Web Filtering page, and Firewall rules on Cipafilters. 


The following table shows how to convert common dot-notation subnet masks to CIDR-notation subnet bits.

As an example: The subnet mask 255.255.0.0, when applied to 172.16.0.0, will cover the addresses 172.16.0.0172.16.255.255. To refer to this same range of addresses in CIDR notation, use 172.16.0.0/16. To refer to the single IP address 172.16.0.1, use 172.16.0.1/32.

Subnet mask Subnet bits Number of IP addresses
255.0.0.0 /8 16,581,375
255.255.0.0 /16 65,025
255.255.255.0 /24 256
255.255.255.128 /25 128
255.255.255.192 /26 64
255.255.255.224 /27 32
255.255.255.240 /28 16
255.255.255.248 /29 8
255.255.255.252 /30 4
255.255.255.254 /31 2
255.255.255.255 /32 1

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