Last updated:
DHCP supplies network configuration automatically. On a typical home LAN, the router gives a device an IPv4 address, subnet mask, default gateway and DNS settings for a lease period. This local address allocation is separate from the way your provider gives the router its internet-facing connection.
The initial lease sequence
- Discover: a client looks for an available DHCP server.
- Offer: a server proposes an address and configuration.
- Request: the client requests the chosen offer.
- Acknowledge: the server confirms the lease.
This familiar DORA sequence describes an initial IPv4 allocation; renewal does not always repeat every broadcast step. DHCPv4 uses UDP server/client ports 67 and 68. The protocol is defined in RFC 2131, with configuration options described in RFC 2132. DHCPv6 and IPv6 router advertisements are different mechanisms.
A sample home-network pool
| Setting | Illustrative value |
|---|---|
| Router / gateway | 192.168.1.1 |
| Subnet | 192.168.1.0/24, mask 255.255.255.0 |
| DHCP pool | 192.168.1.100 through 192.168.1.199 |
| Reserved printer | A supported reservation for its client identity, following the router’s pool rules |
These values are an example, not instructions to replace your current subnet. Inspect the router’s existing LAN range, pool and reservation rules. A printer reservation inside or outside a pool depends on the implementation; do not choose an address already used by another device.
Reservation versus manual static address
A reservation keeps the client using DHCP while the server aims to give it the configured address. A manual static address is entered on the device and bypasses that allocation. Track manual assignments and exclude conflicting pool addresses where required. Randomized wireless MAC addresses or other client identifiers can affect which reservation matches.
Check the client before changing the server
On Windows, inspect the adapter details or use this read-only command:
ipconfig /allCheck whether DHCP is enabled and note the address, gateway, DNS servers and DHCP server. A 169.254.x.x link-local address can indicate that a usable DHCP lease was not obtained; it is not a normal router-assigned internet configuration. On Linux, inspect the connection’s IPv4 automatic/DHCP settings and assigned addresses in the network manager.
Common causes of the wrong result
- An exhausted pool or disabled server.
- A second, unintended DHCP server introduced by another router.
- A client configured with an old manual address.
- A guest/VLAN path that cannot reach the correct server or relay.
- A missing cable or wireless association rather than a DHCP problem.
Use one intended home-LAN DHCP service unless you understand a coordinated multi-server design. Router versus access-point mode affects this arrangement; see our mesh backhaul guide. Our isolation guide explains why successfully receiving a lease does not guarantee access to other devices.