Private Ranges

Lesson 29 of 46 in Coddy's IP Addressing and Subnetting course.

Three address ranges are reserved for use inside networks and are never routed on the public internet:

10.0.0.0/8: anything starting with 10
172.16.0.0/12: 172.16 through 172.31 only
192.168.0.0/16: anything starting with 192.168

Your home Wi-Fi almost certainly hands out 192.168 addresses. The 172 range is the sneaky one: 172.15.x.x and 172.32.x.x are public, because only the second octets 16 to 31 are inside the /12.

Challenge

Easy

The file hosts.txt lists six addresses. Inspect it and print only the private ones, in the order they appear.

Expected output:

10.44.2.9
172.20.3.3
192.168.99.1

Try it yourself

Terminal

All lessons in IP Addressing and Subnetting

1Bits and Binary

Numbers as Bits Binary to Decimal Powers of Two Recap - Binary Warm-up

4CIDR Notation

Goodbye Classes Reading CIDR Block Sizes Recap - CIDR Reading

7Special Addresses

Private RangesLoopback Link-Local Zero and Broadcast

10Capstone - The Office

The Floor Plan Sizing Each Team Carving the Block The Router's View Recap - Ship the Plan

2IPv4 Anatomy

Four Octets The 32-Bit View Network and Host Valid or Not Recap - Read an Address

5Inside a Subnet

Network Address Broadcast Address Usable Hosts First and Last Host Recap - Subnet Facts

8Planning Networks

Right-Sizing VLSM Step by Step Allocation Order Checking for Overlap Recap - Plan a Network

3The Subnet Mask

What a Mask Does Mask to Prefix Prefix to Mask ANDing It Out Recap - Mask Basics

6Subnetting Drills

The Block Size Trick Which Subnet Am I In Splitting a /24 Splitting Again Recap - Subnetting Drills

9IPv6 First Steps

Why IPv6 Reading IPv6 Prefixes in IPv6 Recap - IPv6 Basics

Practice on your own: Terminal playground