Why Are IPv4 Addresses Running Out?

IPv4 addresses are running out because IPv4 has a fixed address space, while demand for internet connectivity has grown beyond the supply of freely available public addresses. Much of that supply has already been allocated. Networks needing additional space must work within the remaining allocation rules or obtain access to existing addresses.

This does not mean an IPv4 address gets used up each time someone visits a website. Existing addresses can keep working. The shortage concerns the supply available for additional assignments.

How many IPv4 addresses are there?

An IPv4 address contains 32 bits. That allows 2³² = 4,294,967,296 possible values, commonly rounded to 4.3 billion. IPv6 expands the address size to 128 bits, as described in RFC 8200.

The IPv4 total is not a count of available public addresses. Some ranges have designated uses, including private networks, loopback, multicast, and documentation. IANA records the status of the major blocks in its IPv4 address-space registry.

An address that looks unused to an outside observer may also be legitimately assigned. It might support an internal system, a backup service, or infrastructure that does not answer unsolicited requests. Lack of a response is not permission to reuse it.

What does IPv4 exhaustion actually mean?

IP addresses are distributed through a hierarchy. IANA allocates resources to Regional Internet Registries, which distribute them within their regions under applicable policies. Providers and other organizations then assign addresses to networks and customers. IANA’s number resources overview explains that system.

Exhaustion occurs at a particular pool or allocation stage. It does not happen everywhere on a single date.

These milestones are documented by ICANN, ARIN, and the RIPE NCC.

Returned or recovered addresses can still become available, and some policies reserve space for specific purposes. For example, the RIPE NCC operates a waiting list for eligible organizations using recovered space. Exhaustion therefore does not mean that no additional allocation can ever occur.

Why can billions of devices still connect?

Not every connected device needs an exclusive public IPv4 address.

A home can use different private addresses for a laptop, phone, and television while sharing one public address. Network address translation, or NAT, keeps track of the connections and translates their addressing as traffic crosses a gateway. This address-sharing mechanism is described in RFC 3022.

Providers can also share public addresses across customers using carrier-grade NAT. These arrangements stretch the utility of existing IPv4 space; they do not increase the number of possible IPv4 values.

Read What Is NAT? and Public vs Private IP Addresses for examples.

Can we simply make more IPv4 addresses?

Adding another digit to an IPv4 address does not create an address that existing IPv4 equipment understands. The protocol’s address field has a fixed size.

Networks can use existing space more efficiently, return resources they no longer need, and redistribute eligible blocks through transfers. However, none of these changes the underlying 32-bit limit.

IPv6 addresses that limit through a different protocol with a larger address field. It requires IPv6 support along the relevant connection path. Our IPv4 vs IPv6 guide explains how networks use both versions during the transition.

What options do businesses have?

Start with the connectivity the application needs, rather than assuming every server requires its own public address.

ARIN describes waiting lists, transfers, and IPv6 deployment in its IPv4 addressing options. For the commercial choices, read What Is IPv4 Leasing? and Leasing vs Buying IPv4 Addresses.

Does IPv4 scarcity mean prices will always rise?

No. A limited supply is not a guarantee of any future price. A particular quote also depends on demand, block size, transaction terms, and suitability for the intended service.

Budget using current offers and the full cost of managing the addresses. Avoid treating a purchase as a guaranteed investment return or assuming a lease rate will remain unchanged without contractual protection.

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