To follow-up on Owen’s points and clarify just a bit (at least to respect to policy in the ARIN region) –
– Portions of IP address blocks are routinely “leased” by ISPs to customers, although such leasing has historically been as part of a bundle including connectivity services.
– Because one needs IP addressed to provide connectivity services, leasing of address space as part of providing connectivity is considered operational need (and as such counts towards utilization of one’s address space)
– Leasing of IP address space independent of connectivity doesn’t fulfill operational need, and hence doesn’t count as utilization when you come back to ARIN seeking additional space (or approval of a transfer inwards of an IP address block)
– Leasing of IP address blocks independent of connectivity is not explicitly recognized in ARIN number resource policy (i.e. there is no policy that specifically allows or prohibits such activity.)
– In the ARIN region, we have fairly clear guidelines requiring documentation [via SWIP, RWHOIS, RDAP…] of significant reassignment/reallocations to connectivity customers (as part of documenting IP address block usage), but no clear requirements for reporting
of reissuance of space via leasing independent of connectivity. Furthermore, all address blocks in the ARIN registry are required to have accurate abuse contacts (unless residential in which case accurate contacts must be in the upstream providers block.)