GB and Gb- what is the difference?

For those who don't understand the difference between 2Gb and 2GB.
2GB = 2 GigaBytes ie 2048 MegaBytes(MB)
on the other hand
2 Gb = 2 GigaBits ie 256 MegaBytes(MB) [ 2048/8 = 256 ]

as 1 Byte = 8 bits

Basics of Networking

What is a firewall?
defines a firewall as "a system or group of systems that enforces an access control policy between two networks." In the context of home networks, a firewall typically takes one of two forms:

Software firewall - specialized software running on an individual computer, or
Network firewall - a dedicated device designed to protect one or more computers.

Both types of firewall allow the user to define access policies for inbound connections to the computers they are protecting. Many also provide the ability to control what services (ports) the protected computers are able to access on the Internet (outbound access). Most firewalls intended for home use come with pre-configured security policies from which the user chooses, and some allow the user to customize these policies for their specific needs.

What are TCP and UDP Ports?

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both protocols that use IP. Whereas IP allows two computers to talk to each other across the Internet, TCP and UDP allow individual applications (also known as "services") on those computers to talk to each other.

In the same way that a telephone number or physical mail box might be associated with more than one person, a computer might have multiple applications (e.g. email, file services, web services) running on the same IP address. Ports allow a computer to differentiate services such as email data from web data. A port is simply a number associated with each application that uniquely identifies that service on that computer. Both TCP and UDP use ports to identify services. Some common port numbers are 80 for web (HTTP), 25 for email (SMTP), and 53 for Dmain Name System (DNS).

What are static and dynamic addressing?

Static IP addressing occurs when an ISP permanently assigns one or more IP addresses for each user. These addresses do not change over time. However, if a static address is assigned but not in use, it is effectively wasted. Since ISPs have a limited number of addresses allocated to them, they sometimes need to make more efficient use of their addresses.

Dynamic IP addressing allows the ISP to efficiently utilize their address space. Using dynamic IP addressing, the IP addresses of individual user computers may change over time. If a dynamic address is not in use, it can be automatically reassigned to another computer as needed.

What is an IP address?
IP addresses are analogous to telephone numbers – when you want to call someone on the telephone, you must first know their telephone number. Similarly, when a computer on the Internet needs to send data to another computer, it must first know its IP address. IP addresses are typically shown as four numbers separated by decimal points, or “dots”. For example, 10.24.254.3 and 192.168.62.231 are IP addresses.

If you need to make a telephone call but you only know the person’s name, you can look them up in the telephone directory (or call directory services) to get their telephone number. On the Internet, that directory is called the Domain Name System, or DNS for short. If you know the name of a server, say www.cert.org, and you type this into your web browser, your computer will then go ask its DNS server what the numeric IP address is that is associated with that name.

Every computer on the Internet has an IP address associated with it that uniquely identifies it