DHCP (Dynamic Host Configuration Protocol)
When a client joins Wi-Fi, it requests for an IP address through the DHCP DORA process.
DORA Process
- Discover – Client broadcasts: “Is there a DHCP server who can give me an IP?”
- Offer – Server responds with the complete IP information- IP address/ subnet mask/gateway/ DHCP server identifier/lease duration
- Request – Client responds with, I would like to have this IP address, please reserve this for me.
- Acknowledge (Ack) – Server responds this is your IP address.
Why do we run into DHCP issues?
- Scope exhaustion – More number of clients holding on to the DHCP lease than the available number of IP addresses in the DHCP pool.
- Improper lease times – Too short- results in quick lease expiration, too long- results in too many stale leases.
- Rogue DHCP server- Rogue DHCP server responds to the DHCP discover broadcast resulting in the client getting incorrect IP address.
- Broadcast storms on the wired network- DHCP discover not reaching the DHCP server because of some congestion on the wired network.
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