Overview:
Private IPs were originally meant as a more secure means of providing IPv4 addresses to devices because private IPs are not routable over the internet. It turns out that private IPs also came in handy as a means to save valuable public IPv4 address space. Without private IPv4 addressing, we would not have anymore public IPv4 addresses to hand out today to new devices. Oh, wait a second. We're almost out of IPv4 addresses! The only regional internet registry that has any IPv4 addresses left is AFRINIC. And they're estimated to run out in April 2019.
In any case, private IPv4 addresses go a long way because they can be used by many, many different people, businesses, devices, etc. You do have to turn them into some sort of public address if you want to route over the internet. That could be via a public IPv4 or IPv6 address. Most likely you'll use Network Address Translation (NAT) to do that, but that's another post altogether.
Study Notes:
Identify the private IP ranges
- Class C: 192.168.0.0 - 192.168.255.255 (65,536 IP addresses)
- Class B: 172.16.0.0 - 172.31.255.255 (1,048,576 IP addresses)
- Class A: 10.0.0.0 - 10.255.255.255 (16,777,216 IP addresses)
PacketTracer Lab: CCNA-1.11-Describe-the-need-for-private-IPv4-addressing.pkt
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