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Master Boot Record

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EXTENDED PARTITION

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The DNS PROTOCOL

The Domain Name System protocol translates domain names into IP addresses (Wikibooks page). When a client wants to open a webpage at www.google.com, a query is sent to a DNS server (a.k.a. name server) to fetch the corresponding IP address. The IP returned by the name server is used to contact the Google web server – the server that hosts the actual website contents. In this post we explain the DNS protocol and the packets involved.



Usually, a client will know the IP address of one or more DNS servers after the DHCP boot process is completed. In order to resolve a hostname, a DNS query packet is sent. All DNS traffic between clients and name servers is encapsulated in UDP, and name servers always run on UDP port 53.

The DNS PACKET STRUCTURE

The structure of DNS packets looks like this:


The flags field (16 bits) has the following structure:

a)  The first (0th)bit indicates query(0) or response(1)
    b) Next three bits (1-4) indicates ‘Standard Query (0)’,
       ‘Inverse Query (1)’ and ‘Server Status Request (2)’.
    c) The 5th bit field indicates Authoritative answer. The
       name server is authoritative for the domain in the
       question section.
    d) The 6th bit field is set if message was truncated. With
       UDP this means that the total size of the reply exceeded
       512 bytes and only the first 512 bytes of reply were
       returned.
    e) The 7th bit field indicates Recursion Desired. This bit
       can be set in a query and is returned in the response.
    f) The 8th bit field indicates Recursion Available or not.
    g) The next 3 bits (9-11) have to be 0.
    h) The next 4 bits (12-15) give a return code where
       0 signifies No Error and 3 signifies Name Error.

QUERY PACKET

When a client sends a query to a name server, the Resource Record fields are empty. The Number of Questions field contains the amount of entries in the Questions field, usually 1. Each question consists of:

Name: A string containing the Internet address being queried
Class: The query class, normally the value 1 for Internet (“IN”).
Type: The record type to be queried, the most common types are:

RESPONSE PACKET

A response sent by a name server to a client will contain the original questions in the Questions fields. Additionally the Resource Record fields contain one or more entries. A resource record entry has the following structure:

The Name Server

 A client that wants to translate a name to an IP address sends a question to the name server(s) on its network. The name server provides an answer to the question, but it might have to contact several other servers to obtain the answer. A lot goes on behind the scenes that the client is blissfully unaware of. A typical scenario where a client looks up abc.company.com looks like this:

1. The client formulates a question and sends it to the name server, expecting an unambiguous answer. The name server will first search its cache (5), and immediately answer the client if the answer is found.
2. If the name server does not know the answer itself, it contacts the root name server. The root name server finds out that it does not know the IP for abc.company.com, but it contains an NS type resource record delegating the .com domain to a subordinate name server. So it returns the IP’s for the authoritative name servers for the .com Top Level Domain (TLD).
3. The name server contacts the authoritative server for the .com domain, which contains an NS type resource record for the company.com domain. It will receive the IP addresses for the authoritative servers for the company.com domain.
4. Then, the authoritative name server for the company.com domain is contacted, again asking for the IP of abc.company.com. This server then solves the query (or not), and transmits the result back to the name server. Finally, the name server sends the answer to the client.
5. The name server also caches the information it obtains during the lookup process for future reference.
6. This process is called iterative lookup, and it the most common approach for name servers that serve clients.

Editing/Compiling Programs on Windows Using MinGW

So, you are new to C or C++ and you want to figure out how to get started? How to run your code? How to create executables? Well, here is all you need to know.

EDITORS: 

There are quite a few editors for C and C++, and some which even support multiple other languages. It's up to you to figure out which one works best for you. Some of the better ones that I am aware of are:

Notepad++: Fully featured editor which supports a wide variety of languages out of the box.
http://notepad-plus-plus.org/ 

SciTE: Fast and lightweight cross platform editor. Supports many languages and has a nice syntax highlighting scheme.
http://www.scintilla.org/SciTE.html 

Emerald Editor: Another free and easy to use, small editor. This one also supports a wide variety of programming languages and has macro capabilities. It is based on Crimson Editor, which is no longer in development.
http://www.emeraldeditor.com/ 

TextPad: Quite nice, but not completely free. If you want to keep this editor, you should eventually pay for it.
http://www.textpad.com 
You can get the proper syntax highlighting plugin from:
http://www.textpad.com/add-ons/syna2g.html 

Dev-C++: Included only for the reason that it is extremely popular, Dev C++ is not a stand alone editor, but an all out Integrated Development Environment which uses MinGW/GCC. For the purposes of this tutorial, we'll assume you're not using Dev-C++.
http://www.bloodshed.net/devcpp.html 

COMPILING: 

If you want to compile your source code, here is the "best", most straight-forward way. We will be working with GCC, through the Windows MinGW port, probably the most popular cross platform collection of compilers. It include compilers for C, C++, Objective C, Java as well as Ada.

First, what you need to do is download it from here:
http://sourceforge.net/projects/mingw/files/latest/download 

Next, just install it, no differently than you would install any other program. You can keep all the configurations and settings as their default; that should be good enough.

Alright, this is the part that you need to pay attention to. To use the compiler through command prompt, you will need to edit the Windows PATH environmental variable. If you are using Windows 2000 or Windows XP then you have to:

1. Right click on My Computer from the desktop. 
2. Select properties. 
3. Go to advanced. 
4. Click environmental variables. 
5. Under system variables select Path 
6. Click edit. 
7. Add ; and then where you installed MinGW to. If it was C:/Program Files/MinGW then you would add ;C/Program Files/MinGW/bin to the end of what is already there, do not overwrite what is already there!

Now you're done! To test to see if it worked, and compile programs, open command prompt. If you don't already have a shortcut then it should be somewhere in the accessories folder in the start menu.

When you are already there, you will see the directory which you are already in. Now what you need to do is browse to where the source file is. You will be using DOS style commands, if you are not already familiar with them then:

• type cd to open a folder and browse it. 
• type cd .. to go up, 'back' into a more general directory.
• type dir to see what folders and files are already in the directory

Now, once you are at the location of your source file, to compile it you have to type:


1.    For C++: 
g++ .cpp -o .exe 

2.    For C: 
gcc .c -o .exe 

3.    For Java: 
gcj .java -o .exe


This just specifies which compiler you are using, the source file, and what the resulting executable file will be called.

Straight Line Depreciation Method

The simplest and most commonly used method of depreciation is the straight line method.

The straight line depreciation method takes the purchase or acquisition price, subtracts the salvage value and then divides it by the total estimated life in years.

For example, an equipment worth $1m with an estimated life of five years and salvage value of $100,000 would have the following depreciation schedule and asset value after each year as shown below.

Inventory Valuation Methods in Accounting

Inventory can make up a large amount of the assets on the balance sheet and so knowing how to analyze the inventory, and the method used by management is crucial.

A large part of stock valuation comes from being able to understand how inventory is valued and built.

To put it in the most basic form, inventory is what you have in stock. If you expand on this definition to look at what is involved on the other side of the scale to get the ending inventory amount, the equation for inventory is

Beginning Inventory + Net Purchases – Cost of Goods Sold = Ending Inventory

In words, your beginning inventory along with your purchases and then subtracting what you have sold, results in ending inventory.

But this is where it gets tricky with GAAP rules. Depending on the inventory valuation  method used by the company, the COGS can vary considerably which ultimately affects the ending inventory.

Sadly, it is not as easy as counting what is left on the shelf at the end of the day to get the ending inventory value.

Three inventory valuation methods are used in the US.

1. Average cost method

2. First In First Out (FIFO) method

3. Last in First Out (LIFO) method

1.    Average Cost Method

To put it real bluntly, the average cost method is rarely used. This method does not offer any real convenience or added accuracy.

The equation for average cost method is as follows.

Average Cost = (Total Quantity of Inventory Units) / (Total Quantity of Units)

where

Cost of Goods Sold = (Average Unit Cost) x (Number of Units Sold)

For example if 1,000 toys are produced on Monday at a cost of $1 and then on Tuesday another 1,000 toys are manufactured at a price of $1.05, the average cost method would value the inventory at $1.025 a piece.

2.    FIFO Method

As mentioned previously on aggressive and conservative accounting policies, the FIFO method of valuing inventory is considered to be the aggressive method.

FIFO works like how you maintain your fridge at home. After you have bought some groceries, you tend to place what you just bought at the back of the fridge in order to finish off the older food before it spoils.

In other words, under FIFO, the oldest goods are sold first and the newest goods are sold last.

As a formula it would look like this

Unit Cost per batch = (Cost/Quantity) for each batch

where

Cost of Goods Sold = (Unit Cost x Quantity) for each batch

Using the toy example above, if 1,000 toys were then sold on Wednesday, the COGS would be $1 per unit. The remaining inventory on the balance sheet would then be worth $1.05 each.

3.    LIFO Method

LIFO is the opposite of FIFO. Instead of the oldest inventory being considered as sold first, the newest product is sold first. While the factory analogy works for the FIFO, consider a bakery. By lunch or evening, the bread baked from the morning will not sell as well as the fresh ones from the afternoon batch.

This means that cost of the latest inventory now becomes the COGS with the cost of the oldest inventory being assigned to the inventory value on the balance sheet.

The equation is essentially the same as FIFO since both are calculated based on batches of unit sold.

Unit Cost per batch = (Cost/Quantity) for each batch

where

Cost of Goods Sold = (Unit Cost x Quantity) for each batch

Using the toy example, the 1,000 units sold on Wednesday would have a COGS of $1.05 per unit, with the remaining 1,000 toys being valued at $1 each.

5.    How Inventory Valuation Affects Profits and Assets

As you can see from above, despite ending with the same 1,000 toys, FIFO assigns the inventory value to be $1,050 compared to the LIFO $1,000.

But another point is that the method of inventory valuation does not just affect the balance sheet. Gross profit also varies considerably. How?

Gross Profit = Sales – COGS

COGS differ under FIFO and LIFO, and if your COGS is low, then that means gross profit will increase.

The table below sums up how each of the three inventory valuations vary.

Financial Statement Analysis

 Helping You with Financial Statement Analysis

Accounting is the language of business and to become a successful investor, you also have to think like a businessman.

Warren Buffett said that

“I am a better investor because I am a businessman and a better businessman because I am an investor.”

In other words, business and investing is so closely intertwined that you can not separate it. In order to be a great investor, understanding accounting and performing financial statement analysis is a top priority in your growth as an investor.

I personally struggled a lot with financial statement analysis. Coming from a background with no financial degree or any education in finance, it was difficult to self learn how to analyze financial statements.

But because I went through the hardship of reading many books, magazines, articles and tutorials to improve my knowledge of accounting and the analysis of financial statements, the following articles will make your journey somewhat easier.

1.    How to Master Analyzing the Income Statement

The financial statement is divided into three sections. The income statement is the first part of the financial statement and gets the most attention because it is where the numbers for revenue, net income and earnings per share lives.

This tutorial of the income statement analysis will provide you with insight on how to not just read the income statement, but provide insights on what other points you have to consider as you analyze the income statement in your financial statement analysis.

2.   How to Master Analyzing the Balance Sheet

By understanding the balance sheet, you will be able to gain valuable insight into the financial health of the company. This article uses Circuit City as an example to see why the company went bankrupt.

3.    How to Master Analyzing the Cash Flow Statement

The cash flow statement is a little different than the income statement and balance sheet, because while you can easily compare income statements by quarter, the cash flow statement is more “accrual”. This means that numbers in the cash flow statement add up or accrue throughout the fiscal year.

Best to go read the final section of the financial statement analysis.

4 Timeless Articles on Financial Statement Analysis