What is HotSpot?
An Internet Access Point where you can connect wirelessly to the Internet using your favorite mobile devices. A wi-fi hotspot is basically a place that allows you to wirelessly connect to the internet through your laptop, smartphone or tablet.
How can you manage different database on one system?
A Database Server/System allows the multiple databases to be stored on same machine. Reason behind this : 1) To cut maintenance cost. 2) To cut hardware cost. 3) To cut licence cost. You can install oracle in your system and you can create different Service name / SID's / Databases. For example , I have 2 databases running on my oracle one is used for ABC website and another one is for PQR website. Both of this database don't have relation with each other. If you want you can shutdown any of the database if required without affecting other.
What is the difference between a hub, switch, and router?
A Switch learns and directs traffic to the correct users. It does this by reading the physical address where the packets are being sent to and sends it to the corresponding machine based on its switch table. The switch table is a table which consists of a physical address and which switch port the address is plugged into. Like a switch a hub connects multiple LAN segments and sends traffic from one place to another. The difference though is that a hub sends all traffic to all of its ports. So even if message xyz is supposed to go to the computer on port 1 it will be broadcasted to port 1, 2, 3, 4, 5, 6, 7, and 8. Or however many ports you have. Routers connect different segments of networks as opposed to different segments of LANs. They also connect different networks to other networks. For instance you can have a 126.96.36.199 network connected to a 188.8.131.52 network. They use the actual IP to determine where to direct traffic. What is different about routers though is that they can be secured much more dynamically than switches (hubs have virtually no security). For instance a router connects a home network to the ISP and performs NAT (network address translation) as a security feature.