# CIDR Trainer — IPv4 and IPv6 subnet drills > Network subnet calculation trainer with IPv4 and IPv6 drills and calculators. (iPhone/iPad app by David Root.) - Source: https://appshunter.io/ios/app/cidr-trainer/id1608806016 (this page in markdown: same URL + `.md`) - Developer: [David Root](https://appshunter.io/developer/1770929653) - Category: Developer Tools, Education - Price: Free with in-app purchases - Rating: 5.00/5 from 1 App Store ratings - Age rating: 4+ - Requires: iOS 15.0 · 2 MB - Languages: English - Released: 2022-02-20 - Data updated: 2026-06-13 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/cidr-trainer/id1608806016/reviews.md ## What is 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 ## Key features - IPv4 and IPv6 subnet drills - Network subnet calculators - Address shortening and lengthening drills - Terminology drills - Integrated documentation - iCloud progress syncing ## Pricing and in-app purchases Base price: Free. **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Full Unlock | Free | one-time | ## Frequently asked questions about CIDR Trainer ### How many drills can I try for free in CIDR Trainer? You can try each training drill for free up to 20 times. After this limit, you can access other drills or purchase a permanent unlock for all features. ### What is the price of the full unlock for CIDR Trainer? The price for the 'forever full-unlock' is available in your region via in-app purchases. One purchase unlocks all versions of the app across iOS, iPadOS, and macOS. ### Does CIDR Trainer have ads? No, CIDR Trainer does not contain advertisements. The app is free to download and offers an optional in-app purchase for full functionality. ### What devices is CIDR Trainer compatible with? CIDR Trainer is compatible with macOS, iPhone, iPad, and iPod devices. It utilizes iCloud to sync your drill progress across these platforms. ### How often is CIDR Trainer updated? The latest version, 1.2, was released on March 1, 2022. The initial release was on February 20, 2022, indicating relatively frequent updates for a developer tool. ### What kind of subnetting drills does CIDR Trainer offer? CIDR Trainer offers a wide range of drills including IPv4 and IPv6 CIDR drills, hexadecimal and binary conversions, address shortening/lengthening, and terminology drills. ### Can I get help while using CIDR Trainer? Yes, each training drill in CIDR Trainer features a 'help' button located in the top-right corner. This button provides access to related documentation for assistance. ### What is the age rating for CIDR Trainer? CIDR Trainer has an age rating of 4+. This indicates it is suitable for a broad audience, including younger learners interested in network concepts. ## Version history (last 3 releases) ### 1.2 — 2022-03-01 Fixed a bug that could cause a crash in IPv4 address type drill Fixed an error in the IPv6 address lengthening drill for :: and ::1 cases Several cosmetic fixes Changed iOS support to start at 15.0 instead of 15.2 ### 1.1 — 2022-02-27 Major update adding a large number of IPv6 drills Added IPv4/IPv6 CIDR Calculators Fixed a bug related to iCloud sync of progress ### 1.0 — 2022-02-20 No release notes. ## Apps similar to CIDR Trainer | App | Rating | Price | Category | | --- | --- | --- | --- | | [Buffer Editor - Code Editor](https://appshunter.io/ios/app/buffer-editor-code-editor/id502633252) | 3.9 (157) | Free | Developer Tools | | [La Terminal: Mosh & SSH Client](https://appshunter.io/ios/app/la-terminal-mosh-and-ssh-client/id1629902861) | 4.7 (101) | Free | Developer Tools | | [MQTT Spy](https://appshunter.io/ios/app/mqtt-spy/id1564422794) | 4.0 (1) | $0.99 | Developer Tools | | [Twine Desktop](https://appshunter.io/ios/app/twine-desktop/id6451390893) | 5.0 (1) | Free | Developer Tools | | [PalmWeb](https://appshunter.io/ios/app/palmweb/id840781631) | — | $0.99 | Developer Tools | | [Network Sniffer](https://appshunter.io/ios/app/network-sniffer/id6450956188) | 4.6 (159) | Free | Developer Tools | ## More apps by David Root - [Netrek](https://appshunter.io/ios/app/netrek/id1456021641) - [Hex Madness](https://appshunter.io/ios/app/hex-madness/id1511450966) All apps by David Root: https://appshunter.io/developer/1770929653 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-13.*