Addresses and Subnetting

What an IP Address Really Is

8:26Coming soon

A new laptop, set up by hand on Friday. Monday it can print, because the printer is next door, and it can reach nothing else, including the internet. The address on it is fine. The number underneath it is not. This is the first lesson of the Addresses and Subnetting series: what the four numbers of an IPv4 address are, what the slash and the subnet mask do, and the one test every computer runs before it sends anything.

You'll learn

Why an IP address is four numbers from 0 to 255: thirty-two bits, grouped in eights, written the friendly way
Two addresses in one: the network part and the host part, and where the split is
The slash and the subnet mask: /24 and 255.255.255.0 are the same sentence in two languages
The street test: how a computer decides whether a destination is local or goes to the default gateway — and why the gateway MUST be on the same network
The two addresses every network keeps for itself: the network address and the broadcast address (256 numbers, 254 hosts on a /24)
The real thing: a wrong subnet mask (255.255.255.240) that shrinks the laptop's network to sixteen addresses, seen in ipconfig and ping, and fixed in the adapter settings
Exam corner: which address is on the same network as 192.168.1.20/28

Chapters

0:00The laptop that can only see the printer
0:38The sign on the lawn
0:59Four numbers, thirty-two lamps
1:46Two addresses in one: the street and the house
2:29The slash and the subnet mask
2:59The street test
3:30The gate must be on your street
3:58House zero and the bell tower
4:29Friday: the wrong mask
5:23The real names
6:00Three numbers: address, mask, gateway
6:44The real thing: ipconfig, ping, and the fix
7:49Exam corner
8:12Recap and next time

Exam objectives: CompTIA Network+ N10-009: 1.7 (IPv4 addressing: subnet masks, prefix length, network and broadcast addresses), 5.2 (incorrect subnet mask, incorrect default gateway), 5.5 (ipconfig, ping).

Byte City is not affiliated with or endorsed by CompTIA.