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 Technology Questions

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Q:

What is an error-first callback ?

Answer

Error-first callbacks are used to pass errors and data as well. You have to pass the error as the first parameter, and it has to be checked to see if something went wrong. Additional arguments are used to pass data.


 


fs.readFile(filePath, function(err, data) {
if (err) {
// handle the error, the return is important here
// so execution stops here
return console.log(err)
}
// use the data object
console.log(data)
})

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Subject: Java
Job Role: Analyst , Database Administration , IT Trainer

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Q:

So if md5( ) generates the most secure hash, why would you ever use the less secure crc32( ) and sha1( )?

Answer Crypto usage in PHP is simple, but that doesn’t mean it’s free. First off, depending on the data that you’re encrypting, you might have reasons to store a 32-bit value in the database instead of the 160-bit value to save on space. Second, the more secure the crypto is, the longer is the computation time to deliver the hash value. A high volume site might be significantly slowed down, if frequent md5() generation is required.
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Subject: PHP

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Q:

When do you override hashcode and equals() ?

Answer

HashCode method return int value. So the Hash value is the int value returned by the hash function .


If you want to do equality check or want to use your object as key in HashMap, we must override hashcode and equals() method.

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Subject: Java
Job Role: Analyst , IT Trainer

5 3253
Q:

How can you find a PL/SQL block, if the cursor is open?

Answer

By use of %ISOPEN status variable.


 

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Subject: SQL

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Q:

In HTML document the tags are

A) hidden keywords B) used to display the content
C) Both A & B D) None of the above
 
Answer & Explanation Answer: C) Both A & B

Explanation:

Hypertext Markup Language (HTML) is the standard markup language for creating web pages and web applications.

HTML tags are the hidden keywords within a web page that define how your web browser must format and display the content. Most tags must have two parts, an opening and a closing part. For example, <html> is the opening tag and </html> is the closing tag.

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Filed Under: Web Technology
Job Role: IT Trainer

13 3241
Q:

What is immutable object? Can you write immutable object ?

Answer

Immutable classes are Java classes whose objects can not be modified once created. Any modification in Immutable object result in new object. For example is String is immutable in Java. Mostly Immutable are also final in Java, in order to prevent sub class from overriding methods in Java which can compromise Immutability. You can achieve same functionality by making member as non final but private and not modifying them except in constructor.

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Subject: Java
Job Role: Analyst , Database Administration , IT Trainer , Project Manager

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Q:

What is anonymous FTP and why would you use it

Answer

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user's ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access

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Subject: Network Administration
Job Role: Software Architect

1 3225
Q:

What is the fastest type of JDBC driver ?

Answer

Type 4  (JDBC Net pure Java Driver) is the fastest JDBC driver.  Type 1 and Type 3 drivers will be slower than Type 2 drivers (the database calls are make at least three translations versus two), and Type 4 drivers are the fastest (only one translation).

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Subject: Java

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