Questions

There are two IP address assigned to each device on a Wi-Fi network.

An Internal (Private) and an External (Public) IP address.

Internal IP address is used for communication between Your computer and a smartphone or whatever devices that are connected to that Wifi network. This is unique for each. If they are same the system cannot differentiate between each device.

While, the External IP address is that visible to the the internet - the websites, the internet connected Apps so on. By default, Routers with NAT (all routers today have it) assign same Public IP address to all devices under its network.

We know that, 

Earth is known as Watery planet.

Neptune is known as Blue planet. 

The process that occurs inside the chloroplasts is photosynthesis. The light from the sun is obserbed and combining with water and CO2, plants prepare food for the plants.

A primary key is a special relational database table column or combination of columns designated to uniquely identify all table records. That is, A primary key is a column or set of columns in a table that uniquely identifies tuples (rows) in that table.

A primary key, also called a Primary Keyword.

Main Features Primary key are ::

It must contain a unique value for each row of data.

It cannot contain null values.