What is the Difference Between Legacy Blocks and Contracted IPv4 Blocks?

IPv4 numbers were given out by the United States government through its contractors over a seventeen year period in the 1980s through late 1997. These numbers were allocated in large blocks to encourage the early development of the Internet and are referred to as Legacy number blocks. There are a total of 4,294,967,296 numbers in version 4 of the protocol; nearly 1,896,000,000 or 44% are Legacy numbers. 

Beginning in 1998, certain entities received these numbers from the U.S. government contractor for free. These entities – which would later become the Regional Internet Registries (RIRs) – began issuing IP numbers to organizations under contracts. Those contracts eventually contained a provision under which the organization receiving those numbers agreed not to assert ownership rights. The IPv4 numbers distributed under these contracts are not Legacy numbers but are Contractually-bound numbers; there are contractual restrictions that prohibit the sale of these numbers. The number blocks offered by Addrex, Inc. are not constrained in this, or any other, manner.

In the late 2000s, the Regional Internet Registries (RIRs) transferred Legacy resources to the RIR in the geographical region in which they resided rather than based on how resources were allocated in the past. This Early Registration Transfer (ERX) Project was completed in early 2007.

Today, to register Legacy resources with the RIRs if you do not have an account with the RIR already, you typically sign an agreement and pay a fee. Once registered, you can transfer the rights to your resources. You may retain your Legacy rights, depending on the RIR and type of membership. As of this writing in December 2020, the process for registering and managing Legacy resources with each RIR is as follows, assuming you only need to transfer the blocks and not receive other resources from the RIR: