O que é IPv4?
Um guia completo sobre o Protocolo de Internet versão 4 — o sistema de endereçamento que alimenta a internet moderna. Entenda como o IPv4 funciona, por que os endereços estão se esgotando e o que isso significa para o seu negócio.
What is IPv4?
IPv4, or Internet Protocol version 4, is the fourth revision of the Internet Protocol and the first version to be widely deployed. It is the foundational protocol that enables devices to communicate over the internet by assigning each one a unique numerical address. Every time you visit a website, send an email, or stream a video, IPv4 is working behind the scenes to route data packets between your device and the destination server.
IPv4 uses a 32-bit address scheme, which allows for approximately 4.3 billion unique addresses (2³² = 4,294,967,296). While this seemed like an enormous number when the protocol was designed in the early 1980s, the explosive growth of internet-connected devices — from smartphones and laptops to IoT sensors and cloud servers — has long since exhausted the available pool.
Despite the development of its successor, IPv6, which offers a virtually unlimited address space, IPv4 remains the dominant protocol on the internet today. The vast majority of websites, networks, and services still rely on IPv4, making these addresses a critical and increasingly scarce digital resource.
IPv4 Address Format
An IPv4 address is a 32-bit number typically written in dotted-decimal notation, consisting of four octets separated by periods. Each octet represents 8 bits and can hold a value between 0 and 255. For example, the address 192.168.1.1 is one of the most commonly recognized IPv4 addresses, used as a default gateway in many home routers.
In binary, each octet is represented by 8 binary digits (bits). The address 192.168.1.1 translates to 11000000.10101000.00000001.00000001 in binary. The 32-bit address is divided into two logical parts: the network portion (which identifies the network) and the host portion (which identifies the specific device on that network). The boundary between these two parts is defined by the subnet mask.
Octet Structure
Each IPv4 address consists of four 8-bit octets (bytes), giving a total of 32 bits. Each octet can represent values from 0 to 255 in decimal notation.
Binary Representation
Under the hood, IPv4 addresses are 32-bit binary numbers. For example, 10.0.0.1 is 00001010.00000000.00000000.00000001 in binary.
Dotted Decimal
The standard human-readable format uses four decimal numbers separated by dots (e.g., 172.16.254.1). This notation makes addresses easier to read and remember.
Network vs Host
The subnet mask divides the address into a network portion (identifying the network) and a host portion (identifying the device). For example, in a /24 network, the first 24 bits identify the network.
IPv4 Address Classes
IPv4 addresses were originally organized into five classes (A through E), each designed for different network sizes. This classful addressing scheme determined how the 32-bit address was split between the network and host portions. Although classful addressing has largely been replaced by CIDR (Classless Inter-Domain Routing), understanding the classes remains important for networking fundamentals.
Class A networks (1.0.0.0 – 126.255.255.255) use the first octet for the network ID and the remaining three for hosts, supporting up to 16.7 million hosts per network. Class B (128.0.0.0 – 191.255.255.255) uses two octets each for network and host, supporting 65,534 hosts. Class C (192.0.0.0 – 223.255.255.255) uses three octets for the network and one for hosts, supporting 254 hosts per network.
Class A
Range: 1.0.0.0 – 126.255.255.255. Designed for very large networks with up to 16.7 million hosts. Only 128 Class A networks exist, assigned to major organizations and ISPs.
Class B
Range: 128.0.0.0 – 191.255.255.255. Suited for medium to large organizations with up to 65,534 hosts per network. There are 16,384 possible Class B networks.
Class C
Range: 192.0.0.0 – 223.255.255.255. Designed for smaller networks with up to 254 hosts. Class C is the most common class, with over 2 million possible networks.
Class D & E
Class D (224.0.0.0 – 239.255.255.255) is reserved for multicast groups. Class E (240.0.0.0 – 255.255.255.255) is reserved for experimental and future use.
Private vs Public IPv4 Addresses
Not all IPv4 addresses are created equal. Public IPv4 addresses are globally unique and routable on the internet — they are what web servers, email services, and any internet-facing system uses to communicate. These are the addresses that have become scarce and valuable in the IPv4 market.
Private IPv4 addresses, defined by RFC 1918, are reserved for use within local networks and are not routable on the public internet. The three private address ranges are: 10.0.0.0 – 10.255.255.255 (a single Class A block), 172.16.0.0 – 172.31.255.255 (16 Class B blocks), and 192.168.0.0 – 192.168.255.255 (256 Class C blocks). These addresses can be reused by any organization within their internal networks.
Network Address Translation (NAT) bridges the gap between private and public addresses. NAT allows multiple devices on a private network to share a single public IPv4 address when accessing the internet. While NAT has been instrumental in extending the life of the IPv4 address space, it adds complexity, can break certain applications, and does not eliminate the underlying need for public addresses.
IPv4 Address Exhaustion
IPv4 address exhaustion refers to the depletion of the available pool of unallocated IPv4 addresses. The Internet Assigned Numbers Authority (IANA) allocated its last blocks of IPv4 addresses to the Regional Internet Registries (RIRs) on February 3, 2011, marking a historic milestone in the history of the internet.
Following IANA exhaustion, each RIR gradually depleted its own free pool. APNIC (Asia-Pacific) ran out in April 2011, RIPE NCC (Europe) in September 2012, LACNIC (Latin America) in June 2014, ARIN (North America) in September 2015, and AFRINIC (Africa) in January 2020. Most RIRs now operate waiting lists for small allocations (/24 blocks), but the supply is extremely limited.
The exhaustion was driven by the explosive growth of internet-connected devices, cloud computing, mobile networks, and the Internet of Things (IoT). With only 4.3 billion possible addresses and billions of devices needing connectivity, the math simply could not work. This scarcity has given rise to a thriving secondary market where organizations buy, sell, and lease IPv4 addresses.
The IPv4 Address Market
The IPv4 address market emerged as a direct consequence of address exhaustion. Since new IPv4 addresses can no longer be obtained from RIRs through traditional allocation, organizations that need public IPv4 space must acquire it from existing holders through regulated transfers. This secondary market has grown into a mature, transparent marketplace with established pricing, professional brokers, and clear transfer procedures governed by each RIR.
IPv4 brokers like IPv4Center facilitate these transactions by connecting buyers and sellers, performing due diligence (including blacklist screening across 300+ databases), managing the RIR transfer process, and providing escrow payment protection. Prices vary by block size and RIR region, with per-IP costs typically ranging from $19 to $35 as of 2026. Organizations can also choose to lease IPv4 addresses for lower upfront costs, making IP space accessible regardless of budget.
Perguntas Frequentes
Perguntas comuns sobre IPv4 e endereçamento de internet.
O IPv4 usa endereços de 32 bits (aproximadamente 4,3 bilhões de endereços únicos), enquanto o IPv6 usa endereços de 128 bits (aproximadamente 340 sextilhões). O IPv6 foi projetado para resolver o esgotamento do IPv4 e inclui melhorias como cabeçalhos simplificados, IPsec integrado e sem necessidade de NAT. No entanto, o IPv4 continua sendo o protocolo dominante.
Os 4,3 bilhões de endereços fornecidos pelo esquema de 32 bits do IPv4 não foram suficientes para acompanhar a explosão de dispositivos conectados, serviços em nuvem e redes móveis. A IANA distribuiu seus últimos blocos IPv4 em 2011, e todos os cinco RIRs esgotaram seus pools livres desde então.
Sim, mas não através da alocação tradicional de RIR. Você pode adquirir endereços IPv4 no mercado secundário comprando ou alugando de detentores existentes. Corretores como IPv4Center facilitam essas transferências com proteção de custódia e gerenciamento completo de transferências RIR.
Endereços IPv4 privados (definidos pela RFC 1918) são reservados para uso em redes internas e não são roteáveis na internet pública. As faixas são 10.0.0.0/8, 172.16.0.0/12 e 192.168.0.0/16. Dispositivos usando endereços privados acessam a internet através de NAT (Network Address Translation).
Em 2026, os endereços IPv4 custam aproximadamente $19–$35 por IP, dependendo do tamanho do bloco e da região RIR. Blocos maiores oferecem preços mais baixos por IP. Os blocos RIPE NCC comandam preços premium devido à alta demanda europeia.
Uma transição completa é improvável no curto prazo. Embora a adoção do IPv6 esteja crescendo, a grande maioria da infraestrutura da internet ainda depende do IPv4. A maioria dos especialistas espera que ambos os protocolos coexistam por muitos anos, o que significa que os endereços IPv4 continuarão mantendo um valor significativo.