A static address is configured to remain fixed until an administrator or automation changes it. A dynamic address is selected automatically and may change as a lease, network attachment, prefix, or privacy policy changes.
IPv4 networks use the Dynamic Host Configuration Protocol (DHCP) for leased addresses and parameters including a default gateway and DNS servers. IPv6 interfaces may use stateless address autoconfiguration, DHCPv6, manual configuration, or combinations of these methods. A DHCP reservation can repeat an address under centralized assignment.
Key points
SelectionUse stable addresses where other systems must reliably reach a stable service endpoint, and managed dynamic assignment where flexibility and centralized configuration matter more.
LifecyclePrevent duplicates, record assignment time and interface context, update name records where required, and plan renumbering instead of assuming an address is permanent.
Security considerationTreat address-based allowlists and logs as contextual evidence. Addresses can be reassigned, shared through NAT or proxies, spoofed in some traffic, or changed by an attacker with local control.
Important limitationStatic does not mean public, and dynamic does not mean private or anonymous. Neither assignment method authenticates a device or user, authorizes access, or encrypts traffic.