Interview Questions and Answers for 'Ab' | Search Interview Question

Interview Questions and Answers for 'Ab' - 364 question(s) found - Order By Rating

Q1. Why do we do transformation on the observable itself rather than doing it in the subscriber ?

Ans. Because that way we just need to do that transformation at one place and not within each subscriber. Single source of truth.

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Q2. What does pipe does on an observable ?

RxJs

Ans. With pipe we specify the operator function to which this observable is passed for transforming the observable.

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Q3. What is the difference between Subject and Observable ?

Angular

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Q4. What is the main difference between unique key and primary key ?

Database

Ans. Primary key will not accept NULL values whereas Unique key can accept one NULL value.

A table can have only primary key whereas there can be multiple unique key on a table.

A Clustered index automatically created when a primary key is defined whereas Unique key generates the non-clustered index.

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Q5. Interface vs Abstraction

Core Java

^{This question was recently asked at 'Oracle financial services'.This question is still unanswered. Can you please provide an answer.}

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Q6. Difference between XSS and CSRF ?

Security

Ans. SRF attack requires an authenticated session, whereas an XSS attack doesn’t.
XSS doesn’t require any user interaction.CSRF is restricted to the actions the victim can perform.
XSS requires a vulnerability to happen, whereas CSRF relies on tricking the user to click a link or access a page.
CSRF can only send an HTTP request but cannot view the response. XSS can send and receive HTTP requests and responses to extract the required data.

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Q7. Can the value of a static variable be changed ?

Core Java

Ans. Yes the value of a static variable can be changed. It's the final keyword that restrict the modification of value not static.

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Q8. How would you design the database schema for an event?

Database

Ans. Broad question, but if the company need velocity, think about use a NO SQL instead of regular SQL databases.

Also prefers materialized views instead of joins to fetch data quickly.

Regarding the database design, there are very good design tools for professional database (to develop proper indexes and good database design) one of the best is QuickDBD

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Q9. Why would a cloud customer use resources in multiple regions and zones ?

Cloud Computing

Ans. 1. Fault Tolerance
2. Better Access by bringing the application closer to the users.

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Q10. differences between drop , delete and truncate

Database

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Q11. What is Throwable ?

Core Java

Ans. Throwable in java is a class that is the superclass of all exceptions and errors which may occurs in java program.It extends obcect class.

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Q12. What is a composite primary key and foreign key ?

Database

Ans. The combination of values from multiple columns in the composite primary key must be unique for each row in the table.
A foreign key, on the other hand, is a field or set of fields in one table that refers to the primary key in another table. It establishes a relationship between two tables based on the values of the foreign key and the primary key.

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Q13. What is SNMP ?

Networking

Ans. SNMP or Simple Network Management protocol is an application layer protocol for exchanging management information between network devices.

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Q14. What can be done to protect the application from DDOS attack ?

Security

Ans. We can set the max number of requests from a given IP or an IP range

We can set the time out so that a single request cannot hold on to resources for too long.

We can identify patterns ( like too many requests from single IP for single page ) and then block such requests.

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_{Like Discuss Correct / Improve DDOS security vulnerability}

Q15. Find the second largest array element without sorting?

Design

Ans. We initialize two variables first and second to INT_MIN as,
first = second = INT_MIN
then Start traversing the array,
If the current element in array say arr[i] is greater
than first. Then update first and second as,
second = first
first = arr[i]
If the current element is in between first and second,
then update second to store the value of current variable as
second = arr[i]
then Return the value stored in second.

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Q16. How can we increase the speed of SQL queries ?

Database

Ans. Using -
1. Prepared Statements
2. Using Indices
3. Using whereby clause only on indexed columns

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Q17. Explain Working of joins in sql.

Database

^{This question was recently asked at 'InfoGain'.This question is still unanswered. Can you please provide an answer.}

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Q18. SQL Questions.

Database

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Q19. Write SQL query to join 2 tables ?

SQL

Ans. Select * from table1 join Select * from table2

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Q20. What are different awt constructs ?

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Q21. Differences between MongoDB and mysql.

Database

^{This question was recently asked at 'RiseSmart'.This question is still unanswered. Can you please provide an answer.}

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Q22. Create DB schema for Employee, Department.

Database

^{This question was recently asked at 'RiseSmart India,RiseSmart'.This question is still unanswered. Can you please provide an answer.}

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Q23. Sort an Employee Object based on Name or Age

Database

Ans. Use Comparable or Comparator interface

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Q24. Can we load environment variables into Properties in Java ? How ?

Core Java

Ans. Yes

new Properties().putAll(System.getenv());

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Q25. Difference between System.getEnv and System.getProperties ?

Core Java

Ans. System.getEnv gets the environment variables where System.getProperties gets Java properties.

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Q26. Does abstract class have public constructor?

Core Java

Ans. Yes, an abstract class can have a constructor in Java.

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Q27. What is the minimum number of tables required to perform a SQL join?

Database

Ans. 1 , We can do self join

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Q28. Can we load Yaml files into AWS DynamoDB ?

Amazon Web Services (AWS)

Ans. No

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Q29. Difference between composite , primary and unique key ?

Database

^{This question was recently asked at 'Thomson reuters'.This question is still unanswered. Can you please provide an answer.}

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Q30. create an SQL query across multiple tables involving outer joins

Database

Ans. Select * from table1 t1Left outer join table2 t2 on t1.tid = t2.id

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