DHCP vs static IP: what is the difference?
Nicolas,
When you connect a device to a network, it needs an IP address to communicate with other machines. This address can be assigned automatically by a DHCP server, or configured manually as a fixed value. These two approaches — DHCP and static IP — serve different needs and each have their advantages.
What is DHCP?
DHCP (Dynamic Host Configuration Protocol) is a network protocol that automatically assigns an IP address to each device that connects to the network. When your computer, smartphone or tablet joins a Wi-Fi or wired network, it sends a DHCP request to the router, which assigns an available IP address for a limited period — called a DHCP lease.
DHCP also assigns other essential network parameters: the subnet mask, default gateway and DNS servers. It is the protocol defined by RFC 2131 from the IETF.
What is a static IP address?
A static IP address (or fixed IP) is an address manually configured on a device. Unlike DHCP, it does not change from one connection to the next. The network administrator or user directly enters the IP address, subnet mask, gateway and DNS in the device settings.
DHCP vs static IP comparison
| Criterion | DHCP | Static IP |
|---|---|---|
| Address assignment | Automatic | Manual |
| Address stability | Variable (may change) | Fixed (never changes) |
| Configuration required | None (client side) | Manual on each device |
| Risk of IP conflict | Managed by DHCP server | Possible if poorly managed |
| Ideal for | Consumer devices, workstations | Servers, printers, IP cameras |
| Network administration | Simplified | More complex at scale |
Advantages of DHCP
DHCP is the default solution on virtually all home and business networks, and for good reasons:
- Zero configuration: no manual intervention is required on client devices
- Centralised management: the router or DHCP server manages all network addresses from a single location
- Avoids conflicts: the DHCP server ensures the same address is not assigned to two devices simultaneously
- Flexibility: devices can join or leave the network without reconfiguration
Advantages of static IP
Static IP is essential in certain professional or technical contexts:
- Permanent accessibility: a server, network printer or IP camera must always be reachable at the same address
- Service hosting: web, FTP or mail servers require a fixed address to be referenced in DNS
- Precise firewall rules: a fixed IP allows stable and predictable filtering rules to be applied
- Network debugging: easier to diagnose since the address does not change
The DHCP lease: how does it work?
When a device obtains an IP address via DHCP, the assignment is temporary. The DHCP lease defines the duration for which the address is reserved for that device — typically between a few hours and a few days depending on the router configuration.
When the lease expires, the device requests renewal. In most cases it receives the same IP address, but this is not guaranteed. This is why some routers allow DHCP reservations: the IP address is assigned dynamically, but always the same for a given device, identified by its MAC address.
Good to know: a DHCP reservation is often the best compromise between the simplicity of DHCP and the stability of a static IP. It allows a device to always receive the same IP address without having to configure it manually on the device itself.
DHCP and public IP: beware of confusion
The DHCP / static IP distinction applies at two distinct levels:
- On your local network (LAN): your router assigns private IP addresses to your devices via DHCP (e.g. 192.168.1.x)
- On the internet (WAN): your ISP assigns a public IP address to your router — generally dynamic (it changes at each reconnection), unless you have subscribed to a fixed IP option
For individuals, the public IP address is almost always dynamic. For businesses hosting services accessible from the internet, a fixed public IP is generally necessary.
Good to know: on most home networks, devices receive a private IP address via DHCP that often remains stable in practice — the router tends to reassign the same address as long as the device reconnects regularly. But this stability is not guaranteed by the protocol, unlike an explicit static configuration.