How IP Addresses Are Assigned (IANA, RIRs, ISPs)
Trace the chain of IP address allocation from IANA to Regional Internet Registries to ISPs and finally to your device.
The IP Address Allocation Hierarchy
IP addresses are not assigned randomly. A structured hierarchy ensures every address is globally unique and properly documented. The chain flows from a single global authority down to your individual device.
IANA (global pool)
-> RIRs (5 regional registries)
-> LIRs / ISPs (local registries and providers)
-> End users (your device)
IANA: The Global Authority
The Internet Assigned Numbers Authority (IANA), operated by ICANN, manages the global pool of IPv4 and IPv6 addresses. IANA allocates large blocks (typically /8 for IPv4) to the five Regional Internet Registries. IANA also manages the root DNS zone, AS numbers, and protocol parameters.
On February 3, 2011, IANA allocated the last five remaining /8 blocks -- one to each RIR -- marking the exhaustion of the central IPv4 pool.
Regional Internet Registries (RIRs)
Five RIRs manage address distribution for their geographic regions:
| RIR | Region | Headquarters |
|---|---|---|
| ARIN | North America | Chantilly, Virginia, USA |
| RIPE NCC | Europe, Middle East, Central Asia | Amsterdam, Netherlands |
| APNIC | Asia-Pacific | Brisbane, Australia |
| LACNIC | Latin America, Caribbean | Montevideo, Uruguay |
| AFRINIC | Africa | Ebene, Mauritius |
RIRs allocate smaller blocks to Local Internet Registries (LIRs), Internet Service Providers (ISPs), and large organizations. Each RIR maintains a public WHOIS database where you can look up who holds any given IP block.
ISPs and Enterprise Allocation
ISPs receive address blocks from their regional RIR and then assign individual IPs or small subnets to customers:
- Residential customers typically receive a single dynamic public IP via DHCP from the ISP.
- Business customers may receive a static IP or a small subnet (/29, /28).
- Hosting providers receive large blocks and assign IPs to virtual machines and dedicated servers.
How Your Device Gets Its IP
At the local network level, devices receive private IP addresses through DHCP (Dynamic Host Configuration Protocol):
- Your device broadcasts a DHCP Discover message.
- The DHCP server (usually your router) offers an available IP from its pool.
- Your device accepts the offer and the router records the lease.
- The lease expires after a set time (often 24 hours) and must be renewed.
# Check your DHCP lease on Linux
cat /var/lib/dhcp/dhclient.leases
# Release and renew on Windows
ipconfig /release
ipconfig /renew
The Transfer Market
Since free IPv4 space is exhausted, organizations now buy and sell address blocks on a secondary market. Prices fluctuate but have ranged from $25 to $60 per IPv4 address. RIRs facilitate these transfers to ensure proper registration and prevent conflicts.