Which version of IP has a 32-bit address space that is known to be depleted?

The correct answer is IPv4, which is characterized by its 32-bit address space. This means it can theoretically support approximately 4.3 billion unique addresses. However, the rapid growth of the internet and the increasing number of devices requiring IP addresses have led to the depletion of this address space. Despite various techniques designed to extend the usability of IPv4, such as Network Address Translation (NAT) and Classless Inter-Domain Routing (CIDR), the exhaustion of available IPv4 addresses has become a significant issue.

IPv5 and IPv3 are versions of IP that were either experimental or never widely implemented, and they do not have a significant address space or relevance in the context of current networking. IPv6, on the other hand, was developed to address the limitations of IPv4 by providing a vastly larger address space using 128-bit addresses, thus effectively solving the depletion issue associated with IPv4. The transition from IPv4 to IPv6 is essential for supporting the future growth of the internet and accommodating the increasing number of connected devices.