Noobish questions

dppagc

uh After working in a big MNC not NOC, I realize that there are many queries related to cisco. I am not sure I should be posting them here

1) When a customer uses Wifi or VPN where do they get the ip from? How is this different from connection via a LAN cable?

2) What kind of traffic goes through the proxy server? There are so many possible sources and destinations.

3) When traffic is blocked how do I investigate if the traffic blocking is due to firewall or proxy server? Maybe it is some other devices.