Why is 192.168.x.x used for private networks? I mean why are those numbers used?

Question

Whose idea was it?!

Answer 1

RFC 1918 Address Allocation for Private Internets. These are the recommended IP address ranges one can use for hosts that do not require direct access to the Internet. These addresses are filtered by Internet Routers and therefore do not have to be globally unique.

These addresses can be used without fear of duplicating a unique IP address owned by another enterprise. If globally unique Internet addresses are required, contact your Internet Service Provider or the NIC (Network Information Center) at [e-mail].

The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets:

10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

wdw

Answer 2

The 10.0.0.0 and 192.168.0.0 address blocks are two of the three address blocks reserved for private intranets (the other is 172.16.0.0-172.131.255.255). These are currently described in RFC 1981 (a revision of the previously issues RFC 1597).

Basically, the RFCs (1981 and its predecessor, 1597), in concert with the IANA (Internet Assigned Numbers Authority), guarantee that these network addresses will never occur on the public internet, and thus can be freely used within organizations for internal intranets. On a technical level, there is no reason one should use one block over the other.

There were some older devices which made use of the fact that restricted which subnet masks that you could specify based upon the IP address of the network. fortunately, most of these devices have long since gone to the great network in the sky.

There is no reason that you cannot, for the purposes of your internal network divide the 10.0.0.0 into multiple 256 (or larger zones), just as there is no reason why you cannot coallesce the 192.168.0.0 block into a single address group.

Answer 3

The Internet Assigned Numbers Authority (IANA) is responsible for setting standards in IP addressing.

Private IP addresses are used by many organizations as a way to conserve public IP space. A private address sits on the inside of an organization's network (LAN or any device hanging off the core router. A port/interface on a router faces the outside world or the public Internet and is given a public IP address. All traffic destined for that network is pointed toward that router interface. On the opposite side of the router, an internal network interface is assigned a private IP address. This address routes to all the devices hanging off the internal network. The use of private network addresses throughout the world help reduce the number of public IP addresses needed to support the millions of hosts hanging off internal networks.

Not as technical, but I hope that it will help you understand it a bit more.

Answer 4

A group call IANA is responsible for the assigning of IP addresses. While the numbers may not appear to be special to us humans, looking at their decimal values, they are important when written in hex (base 16) numbers. They fall at a natural division point in the set of numbers. (Think of it like they fall at a '100' mark in decimal numbers.) So it is a logical place to set aside a group of numbers. (Like setting aside everything between 300 and 400 for a special purpose.)

Since each IP address can only be used once on the Internet, they had to do something to prevent "private networks" from duplicating existing address. So they set aside a range in each of the three major classes of networks (A, B, and the 192.168 range for C). That way everyone knows what addresses can be used without interferring with someone else's "public" IP address.