IPv4
NetworkingIPv4 is the fourth version of the Internet Protocol and the most widely used system for identifying devices on IP networks using 32-bit addresses. It routes traffic between clients and servers by placing source and destination IP addresses in each packet. In web hosting, an IPv4 address can be shared across many sites or assigned exclusively to one service.
How It Works
IPv4 assigns a 32-bit numeric address (commonly written as four decimal numbers separated by dots, such as 203.0.113.10) to a network interface. When a browser requests a website, DNS resolves the domain name to an IPv4 address. Routers then forward packets across networks based on the destination IPv4 address, while the server replies to the source address.
Because public IPv4 addresses are limited, hosting environments often use techniques like NAT (Network Address Translation) and reverse proxies to let many internal servers or many customer accounts share fewer public IPv4 addresses. At the web server layer, multiple websites can also share one IPv4 address using virtual hosting, where the HTTP Host header indicates which domain the client requested.
Why It Matters for Web Hosting
When comparing hosting plans, IPv4 affects reachability, compatibility, and how services are allocated. Some networks and legacy systems still rely heavily on IPv4, so having IPv4 connectivity can be essential even if IPv6 is available. Plan details may specify whether you get a dedicated IPv4 address or share one, which can influence IP-based allowlists, certain email configurations, and how easily you can map multiple services (web, mail, APIs) to your account.
Common Use Cases
- Hosting websites on shared or dedicated IPv4 addresses
- Pointing DNS A records to a server for web and API traffic
- Configuring firewall rules and IP allowlists for admin access or integrations
- Running services that require a stable public endpoint (VPN, game servers, custom apps)
- Email sending and receiving where IP reputation and routing depend on the sending IPv4
IPv4 vs IPv6
IPv4 uses 32-bit addresses, which limits the number of unique public addresses and drives widespread sharing via NAT and proxies. IPv6 uses 128-bit addresses, providing vastly more address space and enabling more direct end-to-end addressing. For hosting buyers, the practical difference is availability and compatibility: IPv4 is nearly universal, while IPv6 support varies by provider, network, and client. Many hosting setups run dual-stack (both IPv4 and IPv6) to maximize reach while preparing for broader IPv6 adoption.