What is DHCP?
DHCP (Dynamic Host Configuration Protocol) is the mechanism your router uses to automatically assign an IP address — and other network settings — to every device that joins the network, so nobody has to configure each device's networking by hand.
When a device connects to your WiFi or plugs into an Ethernet port, it broadcasts a DHCP request. Your router's built-in DHCP server responds with an available IP address from its pool (commonly a range like 192.168.1.2 through 192.168.1.254), along with the default gateway address, DNS server addresses, and a lease time — how long that IP address is reserved for the device before it needs to renew or release it.
This is also how a device's DHCP hostname becomes useful for identification: most devices announce a human-readable name ("Janes-iPhone", "living-room-tv") as part of the DHCP request, which is why checking your router's "connected devices" or DHCP client list is often the fastest way to identify what's on your network — faster than a MAC lookup, especially for devices using a randomized MAC address that has no vendor to look up.
Most home routers also support DHCP reservations — pinning a specific device's MAC address to always receive the same IP address, useful for anything you want to reach at a stable local address, like a printer or a home server.
FAQ
- What happens if two devices get the same IP address?
- A properly functioning DHCP server won't assign the same address twice while a lease is active — IP conflicts on a DHCP network are almost always caused by a device with a manually-configured static IP that happens to fall inside the DHCP pool's range.
- Can I see which devices got which IP from DHCP?
- Yes — your router's admin panel has a "DHCP clients" or "connected devices" page listing every currently-leased IP address, the device's MAC address, and usually its announced hostname.
- What's a DHCP lease time?
- How long an assigned IP address is valid before the device needs to renew it. Typical home router defaults range from a few hours to a few days — short enough that IPs get reclaimed from devices that leave the network, long enough that active devices rarely notice the renewal.