Subnet Basics

Ever get stressed out because you know that there would be subnetting question(s) in the next exam you are taking and that these questions easily take up 10 to 20 minutes of your precious exam time? What if there is more than one question?

The process of converting the subnet to binary and decimal can drive the unfamiliar insane, not to mention the waste of precious time and brain power which can be utilized for other areas of exam preparation.

Let's take a look at a shortcut method that will cut down the time needed to answer these questions without the need for a calculator.

Subnet Basics:

This article assumes that you know how to perform subnetting in the traditional method but it is important to stress that there are only 3 classes of usable IP addresses which are:

Class	Range	Subnet mask	Host bit	Subnet
Class A	1 - 126 (127 is reserved for loopback)	255.0.0.0	24	8
Class B	128 - 191	255.255.0.0	16	16
Class C	192 - 223	255.255.255.0	8	24

You must understand and remember this table well in order to master the shortcut.

Note: You must borrow at least 2 bits and must leave at least 2 bits.

The Subnet Table:

Bits Borrowed (N)	1	2	3	4	5	6	7	8
Bit Value	128	64	32	16	8	4	2	1
Subnet Mask	128	192	224	240	248	252	254	255
Number of Subnets ((2^N)-2)	0	2	6	14	30	62	126	254

Stop: Before continuing, please read this very important article regarding the use of the ((2^N)-2) method of subnetting.

If using the (2^N) method as defined in RFC 1878, your table would look like this instead.

Bits Borrowed (N)	1	2	3	4	5	6	7	8
Bit Value	128	64	32	16	8	4	2	1
Subnet Mask	128	192	224	240	248	252	254	255
Number of Subnets (2^N)	2	4	8	16	32	64	128	256

The subnet table is commonly seen in lecture notes or certification guides but what the author/lecturer did not tell you is how to derive this table on the fly. Its actually quite simple, lets look at it line by line.

1. Bits borrowed, this is the easy one, just remember that the table consists of only 8 columns.
2. Bits Value, remember by heart that the first value starts with 128 and the subsequent values are divided by two.
3. Subnet Mask, this line tells you what the subnet mask would be, to get the figures, add up the corresponding bits value and all of the values prior to it.
128 + 0 (there is no prior value) =128 128 + 64 = 192 192 + 32 = 224 224 + 16 = 240 240 + 8 = 248 248 + 4 = 252 252 + 2 + 254 254 + 1 + 255
4. Number of Subnets, tells you how many subnet you'll get if you use the subnet mask. Just look at the corresponding N value at the top and you can derive the figures.

Once you understand how to derive the subnet table, spend some time practicing. I would advise you to draw out the table once you are in the exam room (before starting the actual exam) it will take you less than a minute.

How to Tackle the Questions:

There are only a few different ways that Microsoft or Cisco can phrase their questions, lets take a look at some examples:

Question Type 1:
If you are to determine the subnet mask based on a number of hosts and an IP address...

Example:
You are assigned an IP address of 172.30.0.0 and you need 1000 hosts on your network, what is your subnet mask.

1. Determine the number of bits needed for the hosts. In this scenario, we need ten bits as 2^10 = 1024 (the question asks for 1000 hosts only).
2. Determine the number of bits left for the subnet. 32 - (number of bits needed for the host) which is 32-10 = 22 bits.
3. Determine the number of bits actually borrowed. We take the number of bits left for the subnet and minus as many 8s as possible as each 8 represents 1 octal. Therefore 22 - 8 - 8 = 6 bits were borrowed.

Bits Borrowed (N)	1	2	3	4	5	6	7	8
Bits Value	128	64	32	16	8	4	2	1
Subnet Mask	128	192	224	240	248	252	254	255
Number of Subnets (2N-2)	0	2	6	14	30	62	126	254

With reference to the subnet table, 6 bits would have a subnet of 255.255.252.0 . Take note that a total of two 8s were subtracted off, therefore the first two octal would be 255.255.x.x and the 3rd octal was 6 bits borrowed which leaves with 255.255.252.x.

Question Type 2:
If you were given an IP address of 172.30.0.0 and you need 15 subnets...

Bits Borrowed (N)	1	2	3	4	5	6	7	8
Bits Value	128	64	32	16	8	4	2	1
Subnet Mask	128	192	224	240	248	252	254	255
Number of Subnets (2N-2)	0	2	6	14	30	62	126	254

With reference to the subnet table, the subnet mask should be 255.255.248.0. 172.30.0.0 is a Class B address and the subnet should be 255.255.0.0.

Question Type 3:
You are assigned an IP address of 172.30.0.0 and you need 55 subnets, how many hosts do you have per subnet?

1. Determine the number of bits used for the subnet.
   
   

   Bits Borrowed (N)	1	2	3	4	5	6	7	8
   Bits Value	128	64	32	16	8	4	2	1
   Subnet Mask	128	192	224	240	248	252	254	255
   Number of Subnets (2N-2)	0	2	6	14	30	62	126	254

   
   According to the chart, the closest match to 55 subnet would be 62 and therefore, the number of bits borrowed for the subnet is 6. Since 172.30.0.0 is a Class B, we would need to add another 16 bits to the 6 making it 22 bits in total.
2. Determine the number of bits used for the host. Number of bits used for the hosts is 32 - (number of bits used for the subnet) which is 22 = 10 bits. 2^10-2 = 1022, therefore there are a total of 1022 usable hosts in each subnet.

The key to mastering this shortcut is the same as with any other mathematical question - pratice.

Good luck on your next exam.

-Snehal-

iPod Touch Apps List

The applications and games that you find on the best iPod Touch apps list are not just restricted to the Apple iPod Touch. They can be used on the Apple iPhone as well, and most of them can even be used on the Apple iPad. The quantity and the quality of these apps is one of the most attractive points of owning a device developed by Apple Inc, and you can rest assured that you will get productive and useful apps in every category that you look.


There are more than 300,000 apps available in the Apple App Store, and they optimize the use and the features of your iPod Touch. The new Apple iPod Touch 4G has raised the bar even higher for portable MP3 players, and now you can access the Internet with it, make video calls with it, watch videos on it and the various apps are simply tools that are meant to make all these tasks more enjoyable and productive at the same time.


Apple iPod Touch Apps List


With that information in mind, here are some of the top iPod Touch apps that you make use of today, divided into the various categories in the Store.

Category	Top Free App Name	Top Paid App Name
Books	iBooks B&N Bookstore Marvel Comics B&N Nook Stanza	MegaReader Pocket God Comics Dr. Seuss's ABC Audiobooks Ebook Reader
Business	Dragon Dictation Monster.com Jobs Office CamCard Genius Scan	PDF Reader Pro Documents To Go Currency Converter Job Search FedEx Mobile
Entertainment	Netflix Star Wars: Light Saber Duel Aging Booth Gun Builder Talking Honey Cat	Pocket God Remote iBeer AVPlayer Wallpaper Factory HQ
Games	Angry Birds City Zombies Dinosaur Slayer Original Gangstaz Lyric Legend	Rage HD Uno Solitaire LEGO Harry Potter Guitar Hero
Music	Pandora Radio Shazam SoundHound SongCatcher VEVO	Ocarina LaDiDa PocketGuitar Drum Kit Pro GuitarToolkit
Utilities	Spy Cams Mirror in Your Pocket Free Wi-Fi Finder Battery Life Pro Alarm Clock	Barcode Scanner Flashlight iDownloader Mobile Mouse Pro Cloud Browse
Travel	Google Earth Yelp Urbanspoon American Airlines OpenTable	Kayak FlightBoard Zagat To Go New York Subway Disney World Dining
Sports	ESPN ScoreCenter NFL.com College Football Live CBS Sports Mobile Paper Football 3D	ESPN Radio ACC Sports Hunting Call Pele MMA Underground
Productivity	Google Voice Evernote Shopping List Free iTranslate CamScanner Free	Atomic Web Browser Santa's Bag Keynote Remote LogMeIn Ignition Quickoffice Mobile Suite
Health & Fitness	Calorie Counter and Diet Tracker WebMD Mobile Period Tracker Lite Fooducate iMapMyRun	Nike+ GPS iFitness Sleep Machine All-in YOGA BabyBump Pregnancy Pro

You can also find many free iPod Touch apps lists online to get more information on the best iPod Touch apps 2010 that you can get for free. In addition to these categories, there are many more present in the App Store as well, and one can truly spend hours browsing through the various available apps. The paid apps obviously, provide more features and benefits than the free ones, and this is not lost on consumers. Many people prefer to pay for some apps, so as to enjoy their leading characteristics and features.

The top iPod Touch apps know how to make full use of the impressive hardware of the device. The 1 GHz processor and the 3.5 inches Retina-Eye Display combine together to give the user an enriched experience, and this is enhanced by the way certain iPod applications look on the display screen. Video games are becoming more and more popular on the iPod Touch, and the device is fast overtaking the Sony PSP and the Nintendo DS as the most popular handheld gaming device in the world.

With the help of this iPod Touch apps list you can find the best iPod Touch apps ever for your iPod Touch, and you can enjoy it to its extreme. A lot of money and resources are spent by the developers of these apps to give the best results, and each and every single one of them will be useful to you sooner or later.

- SAM - Virus

Is your computer infected by virus named -SAM - ? Are you not able to surf your favorite websites like orkut or proxy sites ? Irritated due to activities of that virus? Here is the solution !!

Download -SAM- Cleaner

One thing I want make clear is that, This is not a “Computer virus”. (You may check the definition of that word on the net) Then what exactly is it ?

It is actually a computer program designed to block the website not expected in colleges, companies or any other official places. This -SAM- program will only block pornographic sites, harmful sites and sites like orkut, my space n so on.

What can be assured is it will not harm your computer in any way, also its not having any kind of destructive purpose. Instead if -SAM- is running, rest of the viruses cant exist in the same computer, yes this is one of the best features of -SAM- program.

-SAM- was actually a module of our project “System Maintenance Suite” - one of the top 8 softwares awarded in India in IIT TechFest !

-SAM- was spread by mistake while experimenting on college PCs, want to say that it was not spread desperately. Still if you don’t like that you may run the removal of -SAM- provided above.

S.M.A.R.T. Server

Following is the abstract of my B.E. final year project :

1.1. Preface

We all are living in the computer era where almost everything is automated and computer controlled. This SMART Server also aims to have complete network management. The system administrator or analyst of the company or organization would be pleased if he is given something that will automatically keep track of all inventories present in the campus, something that manages the clients and the web traffic, something that helps him to solve the problems remotely. Now the wait is over. Yes, that abstract “something” is realized as SMART Server. Its acronym for Self Monitoring, Analysis and Reporting Technology based Server. 

In today’s world, all the things mentioned above are of extreme importance. The organization can see the quick snapshot of organization’s IT structure and assure that everything is alright. If not, then it can take the appropriate actions. The real-time reports can surely help the system controller to work more efficiently and fast. The implementation is totally based on “open source projects” like Apache, PHP, etc. So, in turn, the SMART Server inherits the powerful features, for instance, fast and flexible client-server interaction, security, platform independence, etc.

1.2. Statement of Problem

Consider an organization where there are many computers and other related inventory. Now it is quite necessary for the system administrator or analyst to:

1. Know all devices connected to IT network.
2. Know which software or hardware component is installed on a computer.
3. Have ability to deploy software or configuration scripts on computers.
4. Keep something between users and the Internet to handle web requests.
5. Provide protection for users and use a web cache to make browsing faster.
6. Have total traffic management and content filtering.
7. Be able to solve software related problems remotely.

1.3. Objectives of Project 

Considering the problem statement, moving towards the solution, our project has following objectives.

SMART Server - 

• Should have a proxy server that allows Total Access Control, Total Content Security, allows easy scalability in really large environments and most importantly, easy to implement, manage and tweak, as per every-day needs. 
• Should determine what the components of your network are, how they are configured and when they change. 
• System administrator should be able to resolve the problems remotely. 
• It should be platform independent that is works perfectly under Windows, Linux or any other system architecture. 
• Should have web based interface so that it must be accessible from any browsers. 

Thus, SMART Server, an automated network management suite is exactly “What you want is what you get.”

1.4. Scope of the Project 

Keeping track of your machines is an essential enterprise task that facilitates hardware and software management, license compliance, regulatory compliance, and security. Indeed, a successful asset management solution can save companies time, money, and lots of management headaches. 

Such a solution is essential for tracking all of your hardware and software assets. It can tell you where they're located, how they're configured, and when any changes are made to them. An asset management solution can provide an audit of manufacturer model and serial number, processor configuration, and even memory installed with free slots. An asset management solution can audit this information quickly and thus help an organization.

Another major job of IT manager is to let the clients use the network bandwidth efficiently. This can be achieved using the caching technique. A proxy server helps in monitoring, controlling the network traffic in extra-ordinary way. Use of Virtual Computing technology to solve the client problems is a good idea, which allows one to control the remote computer machine virtually from any location in the world. 

1.5. Organization of the Project

Its acronym for Self Monitoring, Analysis and Reporting Technology based Server. As its name suggests, it provides self monitoring, analysing and reporting of the related data. For this purpose, SMART Server is organized of the following basic modules – 

· SMART Proxy

· SMART AudIT

· SMART Virtual Computing

SMART Proxy:

It is a proxy server is a server which services the requests of its clients by forwarding requests to other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. 

A SMART Proxy can reply to service requests without contacting the specified server, by retrieving content saved from a previous request, made by the same client or even other clients. This is called caching. Caching proxies keep local copies of frequently requested resources, allowing large organizations to significantly reduce their upstream bandwidth usage and cost, while significantly increasing performance. Proxy programs provide a means to deny access to certain URLs in a blacklist, thus providing content filtering. 

SMART AudIT:

The auditing module intelligently “discovers” software installed across the computer network, and collects software file information such as title, product ID, size, date, path, and version. It also compares software inventory data with purchasing information to reveal license deficits and ensure that organizations remain compliant with their licensing agreements.

SMART Virtual Computing:

SMART Virtual Computing is a remote control software package derived from the popular VNC software. With SMART Virtual Computing, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer.