Famous IP Address 192.168.1.X

Question

hi mates :)
there are two IP addresses I see wherever I look:
192.168.1.x (Class C)
172.16.x.x (Class B)
Is there a specific reason makes those addresses special? (Like they are not used as public internet address)
tx in advance for helping

Answer 1

Hi ,
Private Address Space
The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of IP address space for private networks:
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
The first block is a single class A network number, the second block is a set of 16 contiguous class B network numbers, and the third block is a set of 255 contiguous class C network numbers.
If you decide to use private address space, you don't need to coordinate with IANA or an Internet registry. Addresses within this private address space will only be unique within your network. Remember, if you need globally unique address space, you must obtain addresses from an Internet registry.
In order to use private address space, determine which hosts do not need to have network layer connectivity to the outside. These hosts are private hosts, and use private address space. Private hosts can communicate with all other hosts within the network, both public and private, but they cannot have IP connectivity to any external host. Private hosts can still have access to external services via application layer relays.
All other hosts are public and use globally unique address space assigned by an Internet registry. Public hosts can communicate with other hosts within the network, and can have IP connectivity to external public hosts. Public hosts do not have connectivity to private hosts of other networks.
Because private addresses have no global meaning, routing information about private networks is not propagated on outside links, and packets with private source or destination addresses should not be forwarded across such links. Routers in networks that do not use private address space, especially those of Internet service providers, should be configured to reject (filter out) routing information about private networks. This rejection should not be treated as a routing protocol error.
Indirect references to such addresses (like DNS Resource Records) should be contained within the network. Internet service providers should take measures to prevent such leakage.
Advantages and Disadvantages of Using Private Address Space
The obvious advantage of using private address space for the Internet at large is to conserve the globally unique address space. Using private address space also gives you greater flexibility in network design, since you will have more address space available than you could get from the globally unique pool.
The primary disadvantage of using private address space is that you have to renumber your IP addresses if you want to connect to the Internet.
HTH
satish