Information Technology Mock Interview Questions & Practice

What is the difference between CSS Flexbox and CSS Grid, and when would you use each?

Key points to cover:

• Flexbox is one-dimensional (row or column) layout
• Grid is two-dimensional (rows and columns simultaneously)
• Flexbox suits component-level alignment, Grid suits overall page layout

What is the difference between synchronous and asynchronous JavaScript code?

Key points to cover:

• Synchronous code executes line by line, blocking further execution
• Asynchronous code lets other code run while waiting for an operation
• Mentions callbacks/promises/async-await as mechanisms

What is the difference between a GET request and a POST request in the context of a REST API?

Key points to cover:

• GET retrieves a resource without side effects, typically cacheable
• POST creates/submits data
• POST typically has side effects on the server

What is the purpose of a Software Requirements Specification (SRS) document?

Key points to cover:

• Formally documents functional and non-functional requirements
• Agreed upon with stakeholders
• Serves as a reference throughout development and validation

What is regression testing, and when is it performed?

Key points to cover:

• Re-running existing tests after a code change
• Ensures previously working functionality still works
• Performed after bug fixes, new features, or refactors

What is the difference between a Git merge and a Git rebase?

Key points to cover:

• Merge combines two branches via a new merge commit
• Merge preserves both histories
• Rebase replays commits on top of another branch, producing a linear history

What is the difference between authentication and authorization in a security context?

Key points to cover:

• Authentication verifies identity (who you are)
• Authorization determines what an authenticated identity is permitted to do
• Notes the two are checked at different stages of a request

What is the difference between symmetric and asymmetric encryption?

Key points to cover:

• Symmetric uses the same key for encryption and decryption, fast
• Asymmetric uses a public/private key pair
• Asymmetric avoids needing to share a secret key, but is slower

What is Cross-Site Request Forgery (CSRF), and how does it differ from XSS?

Key points to cover:

• Tricks a logged-in user's browser into submitting an unwanted request
• To a site they're authenticated with
• Unlike XSS, doesn't inject/execute attacker script in the victim's browser

Explain how you would detect if two strings are anagrams of each other.

Key points to cover:

• Character frequency count comparison
• Sorting approach as an alternative, O(n log n)
• Discusses the time/space trade-off between the two approaches

How would you find the lowest common ancestor of two nodes in a binary search tree?

Key points to cover:

• Uses the BST property while traversing from the root
• States O(h) time complexity
• Contrasts with general binary-tree LCA needing a full traversal

How does quicksort's pivot selection affect its performance?

Key points to cover:

• Poor pivot choice (e.g. first element on sorted input) degrades to O(n^2)
• Randomized or median-of-three pivot selection helps avoid the worst case
• Connects pivot quality to partition balance

Explain the difference between multithreading and multiprocessing.

Key points to cover:

• Multithreading shares memory within one process, lower overhead
• Needs synchronization to avoid shared-state issues
• Multiprocessing uses separate memory spaces, higher isolation and overhead

Compare paging and segmentation as memory management schemes.

Key points to cover:

• Paging uses fixed-size units, transparent to the programmer
• Segmentation uses variable-size logical units (code/data/stack)
• Notes segmentation can suffer external fragmentation

How does a condition variable work, and what problem does it solve?

Key points to cover:

• Lets a thread wait/block until a specific condition becomes true
• Signaled by another thread
• Solves busy-waiting inefficiency compared to polling a flag

What is a subquery, and give an example of when you'd use one.

Key points to cover:

• A query nested inside another query
• Useful for filtering based on an aggregate or related table result
• Gives a concrete example (e.g. rows above a subquery-computed average)

Explain Third Normal Form (3NF) and what problem it solves.

Key points to cover:

• 2NF plus no transitive dependency
• Non-key columns must depend only on the primary key
• Removes redundancy caused by indirect (transitive) dependencies

Explain the difference between the READ COMMITTED and REPEATABLE READ isolation levels.

Key points to cover:

• READ COMMITTED prevents dirty reads
• READ COMMITTED still allows non-repeatable reads within a transaction
• REPEATABLE READ additionally prevents non-repeatable reads