What is the difference between static and dynamic IP address assignment, and when is each used?

Static addressing means manually typing in the IP details and is used for infrastructure (routers, switches, servers, printers); dynamic addressing via DHCP leases addresses automatically from a pool and is used for general end-user devices.

The choice comes down to whether an address needs to stay predictable or can be handed out on demand. Devices that other machines must reliably find — a default gateway, a DNS server, a printer, a web server — get static addresses configured by hand so the address never moves. Ordinary clients like laptops and phones come and go constantly, so configuring each one manually would be tedious and error-prone; instead a DHCP (Dynamic Host Configuration Protocol) server leases them an address automatically from a pool. Doing it this way also prevents two devices from being given the same address, since the server tracks what is already in use.

Static addressing:

• IP address, subnet mask, gateway, etc. are entered manually.
• Used for network devices and servers — gateway routers, switches, servers, and printers — whose addresses should not change.

Dynamic addressing (DHCP):

• The DHCP server assigns (leases) an address from a configured range called a pool.
• Used for general-purpose hosts, such as end-user devices, that connect and disconnect frequently.

Why it matters: Many networks use both at once — predictable static addresses for things other devices must reliably find, and hands-off DHCP for the many transient clients, which avoids manual configuration and address conflicts.

Go deeper:

• IP address — static and dynamic (Wikipedia) — when persistent static addresses suit infrastructure and why DHCP leases suit transient clients.

• DHCP (Wikipedia) — how the server leases addresses from a pool and tracks them to prevent two hosts getting the same one.