Powers of 2 are important to understand and memorize for use with IP subnetting.

To review powers of 2, remember that when you see a number with another number to its upper right (called an exponent), this means you should multiply the number by itself as many times as the upper number specifies.

For example, 2 power of 3 is 2 × 2 × 2, which equals 8. Here’s a list of powers of 2 that you should commit to memory:

2 power of 1 = 2
2 power of 2 = 4
2 power of 3 = 8

2 power of 4 = 16
2 power of 5 = 32
2 power of 6 = 64
2 power of 7 = 128
2 power of 8 = 256
2 power of 9 = 512
2 power of 10 = 1,024
2 power of 11 = 2,048
2 power of 12 = 4,096
2 power of 13 = 8,192
2 power of 14 = 16,384

Before you get stressed out about knowing all these exponents, remember that it’s helpful to know them, but it’s not absolutely necessary. Here’s a little trick since you’re working with 2s: each successive power of 2 is double the previous one.

This is 7 OSI layers you should to know and understand before start to learn the next step of networking. Follow me to learning now!

Application Layer
The seventh layer, or topmost layer, of the OSI Reference Model is the application layer. It provides the interface that a person uses to interact with the application. This interface can be command-line-based or graphics-based. Cisco IOS routers and switches have a command-line interface (CLI), whereas a web browser uses a graphical interface.

Note : that in the OSI Reference Model, the application layer refers to applications that are network-aware. There are thousands of computer applications, but not all of these can transmit information across a network. This situation is changing rapidly, however. Five years ago, there was a distinct line between applications that could and couldn’t perform network functions.

A good example of this was word processing programs, like Microsoft Word they were built to perform one process: word processing. Today, however, many applications–MicrosoftWord, for instance–have embedded objects that don�t necessarily have to be on the same computer. There are many, many examples of application layer programs. The most common are telnet, FTP, web browsers, and e-mail.

The International Organization for Standardization (ISO) developed the Open Systems Interconnection (OSI) Reference Model to describe how information is transferred from one machine to another, from the point when a user enters information using a keyboard and mouse to when that information is converted to electrical or light signals transferred along a piece of wire or radio waves transferred through the air. It is important to understand that the OSI Reference Model describes concepts and terms in a general manner, and that many network protocols, such as IP and IPX, fail to fit nicely into the scheme explained in ISO’s model.

Therefore, the OSI Reference Model is most often used as a teaching and troubleshooting tool. By understanding the basics of the OSI Reference Model, you can apply these to real protocols to gain a better understanding of them as well as to more easily troubleshoot problems.

ISO developed the seven-layer model to help vendors and network administrators gain a better understanding of how data is handled and transported between networking devices, as well as to provide a guideline for the implementation of new networking standards and technologies. To assist in this process, the OSI Reference Model breaks the network communication process into seven simple steps.

Step 6: Figure Out the Host Addresses

Step 6 is the easiest step. If you recall, any address between the network and directed broadcast address is a host address for a given network. We can then complete the rest of our addressing for 192.168.1.0, as is shown in table as below.

If you look at the very first subnet in this table, 192.168.1.0, you’ll see that it has a total of 14 host addresses, which matches are formula: 2 power of Y - 2, 2 power of 4 - 2 = 14 hosts. For the CCNA Exam, you will need to understand how to do IP addressing.

Of course, on the job, you can cheat and use an IP subnet calculator.