CIDR Trainer

CIDR Trainer trains users to perform network subnet calculations. It uses directed training drills while providing documentation to instruct users to perform each step of network subnetting calculations.

CIDR Trainer includes IPv4 and IPv6 CIDR calculators.

Version 1.1 includes the following categories of drills:

1-digit hexadecimal and binary drills

2-digit hexadecimal and binary drills

IPv4 terminology drills

IPv4 prefix-length drills

IPv4 CIDR drills

IPv6 Address Shortening and Lengthening Drills

IPv6 Terminology Drills

IPv6 CIDR Drills

IPv4 and IPv6 CIDR Calculators

You may try each training drill for free 20 times. After that you may try the other drills or purchase a permanent unlock of all training drills for a low price (see in-app purchases for the "forever full-unlock" price in your region). One purchase unlocks all versions of the app (iOS, iPadOS, and MacOS). CIDR Trainer uses iCloud to sync drill progress between your devices.

Each training drill has a "help" button in the top-right which provides related documentation

Full list of drills: (you may try them in any order)

1-digit hex -> decimal

1-digit decimal -> hex

1-digit hex -> binary

Binary -> 1-digit hex

4-digit binary -> decimal

Decimal -> 4-digit binary

1-bit AND

2-digit hexadecimal -> decimal (easy multiples of 16)

Decimal -> 2-digit hexadecimal (easy multiples of 16)

2-digit hexadecimal -> binary

binary -> 2-digit hexadecimal

2-digit hexadecimal -> decimal

Decimal -> 2-digit hexadecimal

8-digit binary -> decimal

Decimal -> 8-digit binary

8-bit AND

Valid IPv4 address recognition

IPv4 address types

IPv4 prefix-length to binary netmask

IPv4 binary netmask to prefix-length

IPv4 prefix-length to hexadecimal netmask

IPv4 hexadecimal netmask to prefix-length

IPv4 prefix-length to dotted-decimal netmask

IPv4 dotted-decimal netmask to prefix-length

IPv4 CIDR Drills:

Number of IPs in a CIDR

Number of usable unicast IPs in a CIDR

CIDR to network address in binary

CIDR to network address in decimal

Well-formed CIDR to broadcast address

Well-formed CIDR to first usable IP address

Well-formed CIDR to last usable IP address

IPv6 Address Shortening and Lengthening Drills:

IPv6 Hextet Shortening

IPv6 Hextet Lengthening

IPv6 Eight Hextet Shortening

IPv6 Eight Hextet Lengthening

IPv6 Double Colon Shortening

IPv6 Double Colon Lengthening

IPv6 Address Shortening

IPv6 Address Lengthening

IPv6 Address Types

Valid IPv6 Sextets

Valid IPv6 Addresses

IPv6 CIDR (prefix / 16) drill

IPv6 CIDR (prefix / 4) drill

IPv6 CIDR (any prefix) drill

IPv4 CIDR Calculator

IPv6 CIDR Calculator