Jim Guckin

Question:

Please don’t laugh at me, but I’ve wondered how my computer gets an IP address from my router?

Renee Newcomb
Ferndale, WA

Answer:

I love questions like these, every computer, tablet, phone or laptop gets an IP address when connected to the internet, but rarely do we think of the process that takes place. So to go over the basic way a new laptop at your house gets a computer.

1. When a new devices connects to your network (either plugged in or via WiFi), it send a broadcast message on the network. This broadcast message is open for anything to respond to, since it doesn’t know the network settings.
2. A DHCP Server (or a router acting as one), will hear the broadcast message and reply to the device with the information that is needed to connect. This would contain the IP address, DNS, how long it can use the IP before needing to check back in.
3. The device then responds back to the DHCP server saying that it wants to use the IP it was offered
4. The DHCP server, then lets the device know it can use them.
5. Now with an IP address, you can see the other devices on the network that are on the network subnet.

I hope that helps you understand the process of DHCP when a devices connects to the network, I tried to make it as simple as possible, and it can get more complicated in a larger network.

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If you have any questions that you want Jim to answer, from business servers to home computers, drop him a line at me@jimguckin.com, and he’ll try to answer your question. Check back every Monday for a new Question and Answer session, and also during the rest of the week for other technical insights.