Network Coordination Centers (NCC)
IP addresses are administered and registered by different Network Coordination Centres (NCC):
RIPE NCC - Europe, the Middle East, and Central Asia
The RIPE Database contains registration details of IP addresses and AS numbers originally allocated by the RIPE NCC.
It shows the organisations that hold the resources, where the allocations were made, and contact details for the networks.
The organisations that hold those resources are responsible for updating their information in the database.
ARIN - North America
ARIN provides services related to the technical coordination and management of Internet number resources in its respective service region.
The ARIN service region includes the USA, Canada, and many Caribbean and North Atlantic islands.
APNIC - Asia/Pacific Region
LACNIC - Latin America and some Caribbean Islands
AfriNIC - Africa Region
AfriNIC is a non-government, not-for-profit, membership based organization, based in Mauritius to serve African Internet Community.
AfriNIC is the Regional Registry for Internet Number Resources for Africa.
Special IP-Address Blocks
0.0.0.0/8 reserved for self-identification
127.0.0.0/8 is reserved for Loopback
169.254.0.0/16 reserved for Link Local
188.8.131.52/24 reserved for 6to4 Relay Anycast
198.18.0.0/15 reserved for Network Interconnect Device Benchmark Testing
255.255.255.255 is reserved for "limited broadcast" destination address
Reserved for Private-Use Networks
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)
The first block is refered to as "24-bit block", the second as "20-bit block", and to the third as "16-bit" block.
Note that (in pre-CIDR notation) the first block is nothing but a single class A network number, while the second block is a set of 16 contiguous class B network numbers, and third block is a set of 256 contiguous class C network numbers.