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Interview questions from top companies, mapped to the exact round they show up in. Prep for what you will actually face.

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Online AssessmentDSA / CodingMachine CodingLow-Level Design

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The Loop aggregates publicly shared interview experiences and curated commonly-asked questions, each labeled with its source. Not affiliated with any company listed.

CC BY-NC 4.0 · © 2026

← Northrop Grumman

Mid Backend at Northrop Grumman

BackendMidNo offer◆ Commonly asked· 2025

Mid backend interview. Fast-paced; expect follow-ups that push on depth.

The loop · 5 rounds

01

Round 01 · 3 questions

DSA / Coding

Data structures & algorithms on a whiteboard or shared editor.

  • Find minimum in rotated sorted array.
    MidMedium◆ Commonly asked
    #binary-search
    PracticeLeetCode↗GeeksforGeeks↗
  • Validate a binary search tree.
    MidMedium◆ Commonly asked
    #tree#dfs
    PracticeLeetCode↗GeeksforGeeks↗
  • Two Sum — return indices of numbers adding to a target.
    MidEasy◆ Commonly asked
    #array#hashmap
    PracticeLeetCode↗GeeksforGeeks↗
02

Round 02 · 2 questions

Machine Coding

Build a working component or service under time pressure.

  • Design and build a URL-shortener service (API + storage).
    MidMedium◆ Commonly asked
    #api#hashing
    PracticeGeeksforGeeks↗Search↗
  • Build a REST endpoint with pagination, filtering and sorting.
    MidMedium◆ Commonly asked
    #api#pagination
    PracticeGeeksforGeeks↗Search↗
03

Round 03 · 1 question

Low-Level Design

Object-oriented / low-level design of a focused module.

  • Design a logging library with levels and sinks.
    MidMedium◆ Commonly asked
    #oop
    PracticeGeeksforGeeks↗Search↗
04

Round 04 · 3 questions

Tech Deep-Dive

Deep questions on your core stack and fundamentals.

  • How do you prevent and detect N+1 queries?
    MidMedium◆ Commonly asked
    #databases#orm
    PracticeGeeksforGeeks↗Search↗
  • Explain database replication lag and how to mitigate it.
    MidMedium◆ Commonly asked
    #databases#replication
    PracticeGeeksforGeeks↗Search↗
  • How does a bloom filter work and when would you use one?
    MidMedium◆ Commonly asked
    #data-structures#probabilistic
    PracticeGeeksforGeeks↗Search↗
05

Round 05 · 2 questions

Behavioral / HR

Values, collaboration, and past-experience (STAR) questions.

  • How do you handle being blocked for several days?
    Mid◆ Commonly asked
    #ownership#star
  • A time you made a mistake in production — what happened next?
    Mid◆ Commonly asked
    #ownership#star

Practice each round across every company

  • DSA / Coding
  • Machine Coding
  • Low-Level Design
  • Tech Deep-Dive
  • Behavioral / HR

◆ This experience is composed from commonly reported questions for this role and level. Real, individually-shared interviews will be layered in over time.