**Table of Contents**- IPv4 Addresses and Ranges
- IPv6 Addresses and Ranges

An IPv4 address is made of 4 numbers separated by dots as in `aaa.bbb.ccc.ddd`, each number ranges from 0 to 255.

An IPv4 address range must conform to one of the following forms:

`*`: the range includes all valid IP addresses,`aaa.*`: the range includes the IPv4 addresses which first part is equal to`aaa`,`aaa.bbb.*`: the range includes the IPv4 addresses which first and second parts are respectively equal to`aaa`and`bbb`,`aaa.bbb.ccc.*`: the range includes the IPv4 addresses which first, second, and third parts are respectively equal to`aaa`,`bbb`, and`ccc`,`aaa.bbb.ccc.ddd-iii.jjj.kkk.lll`: the range includes the IPv4 addresses between`aaa.bbb.ccc.ddd`and`iii.jjj.kkk.lll`,`aaa.bbb.ccc.ddd/n`: the range includes all the IPv4 addresses that belong to the subnet which network prefix or CIDR (Classless Interdomain Routing) notation is`aaa.bbb.ccc.ddd/n`. An IPv4 address that is included in this range has its first`n`bits identical to the first`n`bits of`aaa.bbb.ccc.ddd`,`aaa.bbb.ccc.ddd-iii.jjj.kkk.lll/n`: An IPv4 address that is included in this range is comprised between`aaa.bbb.ccc.ddd`and`iii.jjj.kkk.lll`, and has its first`n`bits identical to the first`n`bits of`aaa.bbb.ccc.ddd`and`iii.jjj.kkk.lll`.

**Example C-1. CIDR Notation Example
**

`220.78.168.0/21` represents IPv4 addresses between `220.78.168.0` and `220.78.175.255`.
Actually, 220.78.168.0 in binary is 11011100 01001110 10101000 00000000. So `220.78.168.0/21` includes all the IPv4 addresses which 21 first bits are 11011100 01001110 10101. Therefore, it represents the range `220.78.168.0-220.78.175.255` (in binary 11011100 01001110 10101*000 00000000* - 11011100 01001110 10101*111 11111111*.)