CheckIP - IP Address Lookup

This IP lookup tool provides a mechanism for finding contact and registration information for any IP address. IP addresses are administered and registered by different organizations (Network Coordination Centres NCC) depending on the global region. This tools allows the lookup the holder of a given IP-address (e.g. a company, your ISP) and extracts the IP block definition and calculates the first IP of the next IP block.

You must choose the right reqion for the IP-address to investigate to get the appropriate information.

Try Calc & Sort-IP to sort and manage IP-blocks and subnetworks, or Check-Me to find out more about your current session.

IP Address Lookup

Online IP Address Lookup
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Registrar (NCC)

Network Coordination Centres NCC

RIPE
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
ARIN provides services related to the technical coordination and management of Internet number resources in its respective service region. The ARIN service region includes Canada, many Caribbean and North Atlantic islands, and the United States.
AfriNIC
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.

Private Address Space

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)

We will refer to the first block 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.