DHCP

01Why DHCP?

Without DHCP, every device would need a manually assigned IP: slow, typo-prone, and worst of all — assign the same IP twice and you get an IP conflict.

With DHCP:

• A device gets an IP automatically the moment it joins
• Central management: the whole range is controlled from one place
• When a device leaves, its IP returns to the pool — nothing is wasted

02What DHCP provides

More than just an IP arrives in a single exchange:

03The DORA process

DHCP works in four steps — the initials spell DORA:

1. Discover

Client → "Any DHCP server on this network? I need an IP!" → Broadcast

2. Offer

DHCP Server → "192.168.1.100 is free, want it?" → Client

3. Request

Client → "Yes, I'd like 192.168.1.100" → Server

4. Acknowledge

Server → "Done, it's yours for 24 hours" → Client

The client doesn't have an IP yet, so its first message goes out as a broadcast — it shouts to everyone on the network, and whichever server has an answer replies.

04IP lease

An IP address isn't granted forever, it's leased:

• Lease time — how long the IP is valid
• Renewal — halfway through, the device quietly asks to renew
• Release — if the device leaves, the IP returns to the pool

Example: a device with an 8-hour lease asks for renewal at hour 4; if renewed, the clock restarts.

05Where does the DHCP server live?

06Static vs dynamic IP

There's a middle path too: DHCP reservation — a MAC address is paired with an IP, so the device always gets the same address while management stays central.

07Try it yourself

08Summary

• DHCP = automatic IP and network configuration
• DORA = Discover, Offer, Request, Acknowledge
• IPs are leased and renewed at half-life
• At home your router does this; servers usually run static IPs