@cyberstudentnewbie said in cyberstudent with basic questions about interface configurations:
DHCP
See it like this :
@home, you have a program called 'a browser'. For example : Edge. Edge connects to a server (there are many server, you as a human, you have to chose a server).
This is what is called a client and server concept.
For "DHCP", it's somewhat identical.
The interface that you've declared as "WAN" is used by a DHCP program ( its process name is dhcpc from DHCP Client) and it sends out over the WAN interface - it actually broadcasts - a request : "Is there a DHCP server out there, as I want to a 'lease').
It's your ISP router, or some other router, farther away, that has a DHCP server, and this server will give your dhcpc a lease == an IP, a DNS, a gateway, and network info.
Now, pfSense is happy, it obtained an IP on it LAN.
Now, lets go one step back. Your pfSense LAN. Most devices, PC's phones, printers, doorbells, etc have a build in DHCP Client.
So it's the same story all over again.
But this time, it is the DHCP Server, that runs on your pfSense LAN (it listens all the time, ready to answer a request coming in from one of your LAN devices) that will hand over a lease to this device, and all other LAN devices.
So, pfSense can use a DHCP client on it's WAN and a DCHP server on its LAN.
They do the same 'related' things. But are opposite in functionality.
Btw : both aren't strictly needed.
You can set up your WAN with static "hard coded" IP settings (network, IP DNS, gateway).
Same thing on your LAN : stop the DHCP server, and "hard" hand code all your devices with static IP settings (IP, network, DNS, gateway).
This will work just fine.