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

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

Q1. What is the difference between Subject and Observable ?

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Q2. 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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Q3. Interface vs Abstraction

Core Java

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Q4. 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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Q5. 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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Q6. How would you design the database schema for an event?

Database

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Q7. 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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Q8. differences between drop , delete and truncate

Database

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Q9. What is a composite primary key and foreign key ?

Database

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Q10. 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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Q11. 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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Q12. 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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Q13. 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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Q14. Explain Working of joins in sql.

Database

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Q15. SQL Questions.

Database

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Q16. Write SQL query to join 2 tables ?

SQL

Ans. Select * from table1 join Select * from table2

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Q17. What are different awt constructs ?

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Q18. Differences between MongoDB and mysql.

Database

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Q19. Create DB schema for Employee, Department.

Database

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Q20. Sort an Employee Object based on Name or Age

Database

Ans. Use Comparable or Comparator interface

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Q21. Can we load environment variables into Properties in Java ? How ?

Core Java

Ans. Yes

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

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Q22. 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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Q23. Does abstract class have public constructor?

Core Java

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

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Q24. 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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Q25. Can we load Yaml files into AWS DynamoDB ?

Amazon Web Services (AWS)

Ans. No

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Q26. Difference between composite , primary and unique key ?

Database

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Q27. 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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Q28. What are the factors on which RedShift is priced on ?

Amazon Web Services (AWS)

Ans. Compute Node Hours
Backup
Data Transfer

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Q29. What is the ideal use case for DynamoDB ?

Amazon Web Services (AWS)

Ans. Fast reads
Much more reads than writes

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Q30. What is the limit of read replicas per database ?

Amazon Web Services (AWS)

Ans. 5

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