From the IP scanning window it will automatically select the local network range, for scanning. In case it does not you may need to enter is manually. My local network is 192.168.1.0/24, which gives me the ip address range of 192.168.1.0 to 192.168.1.255, which is on my ip address range.

Once you start scanning, you shall see a similar input with one hostname raspberrypi.local with the ip address 192.168.1.7 see the following image.

so in this case our discovered ip address for Raspberry Pi is 192.168.1.7

The nmap command (Network Mapper) is an open-source network discovery tool, available for Linux, Mac OS, and Windows.

• To install on Linux Debian or ubuntu or Raspbian, install the nmap package e.g. apt-get install nmap.
• To install on Mac OS or Windows, see the nmap.org download page.

To use nmap to scan the devices on your network, you need to know the subnet you are connected to. First find your own IP address, in other words the one of the computer you’re using to find your Pi’s IP address:

• On Linux (or Mac OS terminal), type hostname -I into a terminal window
• On Mac OS, go to System Preferences then Network and select your active network connection to view the IP address
• On Windows, go to the Control Panel, then under Network and Sharing Center, click View network connections, select your active network connection and click View status of this connection to view the IP address

Now you have the IP address of your computer, you will scan the whole subnet for other devices. For example, if your IP address is 192.168.1.5, other devices will be at addresses like 192.168.1.2, 192.168.1.3, 192.168.1.4, etc. The notation of this subnet range is 192.168.1.0/24 (this covers 192.168.1.0 to 192.168.1.255).

Now use the nmap command with the -sn flag (ping scan) on the whole subnet range. This may take a few seconds:

nmap -sn 192.168.1.0/24

Ping scan just pings all the IP addresses to see if they respond. For each device that responds to the ping, the output shows the hostname and IP address like so:

Starting Nmap 6.40 ( http://nmap.org ) at 2014-03-10 12:46 GMT
Nmap scan report for hpprinter (192.168.1.2)
Host is up (0.00044s latency).
Nmap scan report for Gordons-MBP (192.168.1.4)
Host is up (0.0010s latency).
Nmap scan report for ubuntu (192.168.1.5)
Host is up (0.0010s latency).
Nmap scan report for raspberrypi (192.168.1.7)
Host is up (0.0030s latency).
Nmap done: 256 IP addresses (4 hosts up) scanned in 2.41 seconds

Here you can see a device with hostname raspberrypi has IP address 192.168.1.7.