An IP address tells networks where to deliver data. Understanding the type of address you have makes it easier to connect domains, host services, configure firewalls, and diagnose why a system cannot be reached.

IPv4 and IPv6

IPv4 uses addresses such as 192.0.2.10. Its address space is limited, so networks often share public addresses through Network Address Translation, or NAT.

IPv6 uses a much larger address format, such as 2001:db8::10. It supports the continued growth of internet-connected systems, but it still requires correct DNS, routing, and firewall rules.

Public and private addresses

Public IP address

A public address can be routed across the internet. Websites, VPN gateways, and public APIs commonly use one directly or through a load balancer.

Private IP address

A private address is used inside a local or cloud network. It is not directly reachable from the public internet and usually connects outward through NAT.

Static and dynamic assignment

A static address remains consistent. It is useful when DNS records, allowlists, remote access, or hosted services depend on a predictable destination.

A dynamic address can change automatically. It is common for home connections and client devices. Dynamic DNS can help in limited cases, but production services usually benefit from a stable endpoint.

Requirements for a reliable internet service

• Reachability: confirm that the address is routed to the correct server or gateway.
• DNS: point the domain's A record to IPv4 and its AAAA record to IPv6 when both are supported.
• Firewall rules: allow only the ports needed by the service.
• NAT or port forwarding: map public traffic to the correct private host when the architecture requires it.
• TLS certificate: secure the domain name used by visitors, not just the numeric address.
• Reverse DNS: configure it carefully for mail servers and other services that depend on address reputation.
• Monitoring: test availability from outside the local network and alert on unexpected changes.

How domains connect to hosting

A visitor enters a domain name, DNS returns the appropriate IP address, and the network routes the request to the hosting service. The web server then uses the requested hostname to select the correct website.

This is why an IP change may require coordinated DNS updates. Lowering the DNS time-to-live before a planned migration can help the new address propagate more quickly, while keeping the old service available reduces disruption during the transition.

Common scenarios

Shared hosting

Many websites can share one public IP address. The hostname in the web request identifies the correct site, so a dedicated address is not automatically required.

Virtual private server

A VPS commonly receives a public address and one or more private addresses. The public interface serves approved traffic while private networking connects internal services.

Office network

Devices typically use private addresses behind a router. The organization may share one public address and use a VPN for controlled remote access.

Mail server

A mail server benefits from a stable public address, consistent forward and reverse DNS, appropriate authentication records, and a clean sending reputation.