Interview Questions

Prices do not reflect the full social cost of production is an example of Market failure.

A market failure occurs when the supply of a good or service is insufficient to meet demand. This results in an inefficient distribution of resources among market participants.

It also occurs if externalities are not accounted for.

If a firm fails to maximize its profits this is not a general market failure.

Contextual selector addresses specific occurrence of an element.
It is a string of individual selectors separated by white space (search pattern), where only the last element in the pattern is addressed providing it matches the specified contex.

The mapreduce framework contains most of the key architecture principles of cloud computing such as:

- Scale: The framework is able to expand itself in direct proportion to the number of machines available.

- Reliable: The framework is able to compensate for a lost node and restart the task on a different node.

- Affordable: A user can start small and over time can add more hardware.

Syntax:

SORT   file-1 ON ASCENDING/DESCENDING KEY key....

USING  file-2

GIVING file-3.

USING can be substituted by INPUT PROCEDURE IS para-1 THRU para-2

GIVING can be substituted by OUTPUT PROCEDURE IS para-1 THRU para-2.

file-1 is the sort workfile and must be described using SD entry in FILE SECTION.

file-2 is the input file for the SORT and must be described using an FD entry in FILE SECTION and SELECT clause in FILE CONTROL.

file-3 is the outfile from the SORT and must be described using an FD entry in FILE SECTION and SELECT clause in FILE CONTROL.

file-1, file-2 & file-3 should not be opened explicitly.

INPUT PROCEDURE is executed before the sort and records must be RELEASEd to the sort work file from the input procedure.

OUTPUT PROCEDURE is executed after all records have been sorted. Records from the sort work file must be RETURNed one at a time to the output procedure.

User names and passwords in PHP can be encrypted using md5 function.

MD5 function calculates the md5 hash of a string. It is basically used for encryption. It is also used for digital signature applications, where a large file must be "compressed" in a secure manner.

Example:

Md5($str);

Crypt() function can also be used to encrypt a string,. It used MD5, DES or blow fish algorithms for encryption.

Syntax:

Crypt(str, salt)

Salt is an optional parameter used to increase the number of characters encoded, to make the encoding more secure

Windows XP supports four major file systems: FAT12, FAT16, FAT32 and NTFS. This means that Windows XP can be installed on these file systems. The use of NTFS is preferred especially when using a bigger hard drive space.

String Args (String []) is an array of parameters of type String.

In Java, 'args' contains the supplied command-line arguments as an array of String objects. In other words, if you run your program as 'java MyProgram Hello World' then 'args' will contain ["Hello", "World"]. When a java class is executed from the console, the main method is what is called.

Oracle HTTP Server is managed by OPMN which stands for Oracle Process Manager and Notification Server. With the use of opmnctl utility we can start, stop and restart Oracle HTTP Server. If we don’t use this utility the configuration management infrastructure cannot detect or communicate with the Oracle HTTP Server processes, and problems may occur.

The startproc command for the case of Windows is: ORACLE_HOME\opmn\bin> opmnctl [verbose] startproc ias-component=HTTP_Server.

To stop Oracle HTTP Server, use the stopproc command: Windows: ORACLE_HOME\opmn\bin> opmnctl [verbose] stopproc ias-component=HTTP_Server.