How to check someone's IP address?

If someone's iPhone is connected to a Wi-Fi-network. How do I check the iPhone's IP-address? I know that I can check it in the iPhone Settings but I want to see it from my PC.
When I run CMD and write "netstat" I see only computers IP-addresses.

Have you tried logging into your wireless router? Some routers will show network information about the devices that are connected, but it may only show its local IP (192.168.x.x)

Log into your router and click on network connections and it should have all the connections to your router. Then you can see the details of that device.

In most cases the iPhone will have an IP-address in the same subnet you are in.
If you know its device name, you may try to ping it with "ping [devicename]" (or "ping [IP]" if you already know the IP). This may or may not work, depends on the phone if it responds to pings at all.
Easiest way would be to log into your router and see which devices are connected to your Wi-Fi - you should find the IP there (and often more info like MAC address, device name etc.).
You can try to ping IPs of your subnet (.1 to.255) manually, but this is usually not worth the effort.
There are programs that can scan the network and give you a list of all devices.

Ping with device

An iphones "IP" address will be with the Wi-Fi router, what you will see is the EXTERNAL router IP, and if you have legal access to the router you will see the NETWORK IP address of the iphone.

However if you do get the ip its useless to you.

If you ever want to see detailed information about the devices connected to your network, use a network scanner. I personally use Advanced IP Scanner v2.0. It will scan your network, and show you information such as ip address, mac address, make/model, computer name, and logged in user.