What system is responsible for assigning IP addresses? The Internet Assigned Numbers Authority, or IANA, coordinates the global assignment of IP address space. It maintains the central numbering system and allocates large address blocks to the five Regional Internet Registries (RIRs).
The RIRs then distribute address space within their regions to Internet service providers, companies, universities, and other networks. This hierarchy prevents different parts of the Internet from independently claiming the same globally routable addresses. IANA also coordinates autonomous system numbers and several other protocol registries.
DHCP is different: it automatically gives devices temporary or local addresses on a particular network. DNS maps names to addresses, while RIPE NCC is one regional registry serving Europe, the Middle East, and parts of Central Asia. IANA is now operated by Public Technical Identifiers, an ICANN affiliate, following the 2016 stewardship transition.