we ran OUT of IP Addresses!!

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About this video

In episode 2 of his ‘You Suck at Subnetting’ / CCNA series, NetworkChuck explains why IPv4 ran out. An IPv4 address has four octets from 0-255, giving 2 to the 32nd power, or 4,294,967,296 addresses — about 4.3 billion. The internet’s creators, working around its official January 1, 1983 birthday, assumed that was inexhaustible and mismanaged it through the class system. Class A (default mask 255.0.0.0) locks only the first octet, giving over 16 million hosts per network but only 126 networks, and whole Class A networks were given to companies the creator names such as GE, IBM, AT&T, Xerox, and HP. Class B (255.255.0.0) gives 65,534 hosts and 16,382 networks, while Class C (255.255.255.0) gives 254 hosts and over 2 million networks. Owners can subnet a large allocation into smaller pieces, and using a non-default mask makes a network classless rather than classful — his own home network is given as an example. Class D is reserved for multicast and Class E is experimental, so neither is usable for hosts, and the entire 127.0.0.0/8 range — over 16 million addresses — is loopback for testing, demonstrated by pinging 127.0.0.1. He teases NAT and IPv6 as the band-aids covered next.

Key takeaways

IPv4 exhaustion comes from both demand — phones, watches, appliances, and IoT devices all needing addresses — and wasteful early allocation under the class system
The subnet mask decides network size: 255 in an octet locks that octet, 0 lets it vary — so Class A yields ~16.7 million hosts per network while Class C yields only 256 addresses (254 usable hosts)
Subnetting lets an owner split a huge allocation into smaller networks; using anything other than the class default mask makes the network classless, which is normal practice today
Large parts of IPv4 are unusable for ordinary hosts: Class D is multicast, Class E is experimental, and 127.0.0.0/8 is loopback
Pinging 127.0.0.1 (or any 127.x address) tests your own device’s networking stack because loopback addresses answer on the local machine itself

Episode details: published April 7, 2022 · 16:49 long. Summary written by Self Growth Videos from the episode itself. Business results and any income figures mentioned are NetworkChuck’s own claims, shared for education — they are not typical or guaranteed.

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