IBM Interview Questions and Answers

I prefer classless addressing due to its flexibility and efficient use of IP addresses.

• Classless addressing allows for more efficient use of IP addresses by allowing for variable-length subnet masks.

• Classful addressing is limited to fixed-length subnet masks, which can result in wasted IP addresses.

• Classless addressing also allows for more flexibility in network design and can accommodate networks of varying sizes.

• Classful addressing is outdated and no longer used in modern n...read more

Page replacement techniques are algorithms used in operating systems to manage memory efficiently.

• FIFO (First In, First Out)

• LRU (Least Recently Used)

• LFU (Least Frequently Used)

• Optimal Page Replacement

• Clock Page Replacement

The acid properties of a transaction refer to its key characteristics for ensuring reliability and consistency in database systems.

• Atomicity: A transaction is considered atomic if it is treated as a single unit of work that either completes in its entirety or is fully rolled back.

• Consistency: This property ensures that a transaction transforms the database from one consistent state to another consistent state.

• Isolation: Transactions should be isolated from each other to preve...read more

2NF and 3NF are both normal forms in database normalization, with 3NF being a stricter form of normalization than 2NF.

• 2NF eliminates partial dependencies, while 3NF eliminates transitive dependencies.

• In 2NF, every non-prime attribute is fully functionally dependent on the primary key, while in 3NF, every non-prime attribute is non-transitively dependent on the primary key.

• Example: If a table is in 2NF but not in 3NF, it means there are transitive dependencies present that nee...read more

Quick sort is faster for small arrays, while Merge sort is more efficient for larger arrays.

• Quick sort has an average time complexity of O(nlogn), while Merge sort has a time complexity of O(nlogn) in all cases.

• Quick sort is an in-place sorting algorithm, while Merge sort requires extra space.

• Quick sort is not stable, while Merge sort is stable.

• Quick sort is often used in practice due to its efficiency, while Merge sort is used in external sorting and when stability is requir...read more

Primary key uniquely identifies a record in a table, while foreign key establishes a link between two tables.

• Primary key ensures uniqueness of each record in a table

• Foreign key establishes a relationship between two tables

• Primary key can't have null values, while foreign key can have null values

• Example: In a 'students' table, 'student_id' can be a primary key, while in a 'courses' table, 'student_id' can be a foreign key linking to 'students' table

A view in DBMS is a virtual table created by a query that can be used like a regular table.

• Views are used to simplify complex queries by storing them as a virtual table.

• They can also be used to restrict access to certain columns or rows of a table.

• Views do not store data themselves, but instead display data from the underlying tables.

• Changes made to the data in a view will affect the underlying tables.

• Example: CREATE VIEW view_name AS SELECT column1, column2 FROM table_name W...read more

DDL commands are used to define the structure of database objects, while DML commands are used to manipulate data within those objects.

• DDL commands include CREATE, ALTER, DROP, TRUNCATE, etc.

• DML commands include INSERT, UPDATE, DELETE, SELECT, etc.

• DDL commands are used to create or modify the structure of database objects like tables, indexes, etc.

• DML commands are used to insert, update, delete, or retrieve data from tables.