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Enterprise · Software Engineer Interview Guide

How to Pass the Iliad / Free Software Engineer Interview in 2026

Το DNA της Iliad / Free (TL;DR)

Iliad / Free values candidates who demonstrate a strong entrepreneurial spirit, technical prowess, and a drive to disrupt markets with innovative, cost-effective solutions. They seek individuals who are autonomous, customer-focused, and can thrive in a lean, fast-paced environment.

Οι συνεντεύξεις tech διεξάγονται στα αγγλικά

Ακόμη κι όταν κάνετε αίτηση τοπικά, η ίδια η συνέντευξη γίνεται σχεδόν πάντα στα αγγλικά. Σας δείχνουμε κάθε ερώτηση και prompt πρώτα στα αγγλικά — τη γλώσσα στην οποία θα γίνει η συνέντευξη — με μετάφραση από κάτω για να προετοιμαστείτε στην ισχυρότερη γλώσσα σας.

Το Interview Loop της Iliad / Free

Το onsite loop σας θα αποτελείται τυπικά από 5 γύρους.

  1. 1

    Γύρος 1

    Recruiter Screen
    Motivation, role fit, logistics.
  2. 2

    Γύρος 2

    Coding Screen
    LeetCode-medium algorithmic problems under time pressure.
  3. 3

    Γύρος 3

    System Design
    Distributed systems, trade-offs at scale, architecture under constraints.
  4. 4

    Γύρος 4

    Onsite Coding
    LeetCode-hard, debugging, code clarity, edge cases.
  5. 5

    Γύρος 5

    Behavioral / Leadership
    Past evidence of ownership, influence, resolving conflict.

Η ζώνη κινδύνου: Κορυφαίοι λόγοι που οι υποψήφιοι αποτυγχάνουν

Με βάση τη βάση δεδομένων μας με αποτελέσματα συνεντεύξεων Iliad / Free, αποφύγετε αυτές τις συνηθισμένες παγίδες:

  • Blaming the other party or portraying them as unreasonable without acknowledging their perspective.
  • Focusing on authority or pressure rather than persuasion.
  • Inefficient parsing logic, leading to slow processing of large log files.
  • Jumping to conclusions without analyzing relevant logs (router, ISP, client devices).

Δοκιμάστε τον εαυτό σας: Πραγματικές ερωτήσεις Iliad / Free

Τρία πραγματικά prompts τραβηγμένα από τη βάση δεδομένων μας.

Τύπος · Debugging

A Freebox router is intermittently dropping internet connections for users in a specific building. The logs show occasional 'DHCP lease renewal failures'. Debug this issue, identify potential root causes, and propose a fix.

Τύπος · Data Structures

Design a system to efficiently track and report the number of active mobile users within specific geographic regions (e.g., cities, neighborhoods) in real-time. Assume data streams from millions of devices.

Τύπος · Data Storage

Design a database schema and strategy for storing customer call detail records (CDRs) for Iliad. Consider the massive scale, the need for efficient querying (e.g., by customer ID, time range, call type), and data retention policies.

+ πολλές ακόμη ερωτήσεις, σήματα και επεξεργασμένα παραδείγματα

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Iliad / Free Interview Question Bank

A sample from our database, grouped by round. Sign up to see the full set.

9 of 20 questions shown

1

Recruiter Screen

1
  1. 1

    Τύπος · Motivation

    Why are you interested in joining Iliad/Free, and what excites you about working in the telecom industry specifically?
2

Coding Screen

3
  1. 2

    Τύπος · Algorithmic

    Given a list of cell tower locations (latitude, longitude) and a user's current location, find the N closest cell towers. Consider the Earth's curvature for distance calculation.
  2. 3

    Τύπος · Data Structures

    Design a system to efficiently track and report the number of active mobile users within specific geographic regions (e.g., cities, neighborhoods) in real-time. Assume data streams from millions of devices.
  3. + 1 more questions in this round (sign up to unlock)
3

System Design

3
  1. 4

    Τύπος · API Design

    Design an API for a new Iliad service that allows users to remotely manage their Freebox settings (e.g., Wi-Fi password, port forwarding). Consider security, scalability, and ease of use for developers integrating with it.
  2. 5

    Τύπος · Scalability

    How would you design a system to handle the signaling traffic for Iliad's mobile network, ensuring low latency and high availability, especially during peak hours or major events?
  3. + 1 more questions in this round (sign up to unlock)
4

Onsite Coding

3
  1. 6

    Τύπος · Algorithmic (Hard)

    You are given a list of network connection events, each with a start time, end time, and source/destination IP addresses. Find the longest period during which a specific IP address was continuously connected to the network, possibly through multiple intermediate hops.
  2. 7

    Τύπος · Debugging

    A Freebox router is intermittently dropping internet connections for users in a specific building. The logs show occasional 'DHCP lease renewal failures'. Debug this issue, identify potential root causes, and propose a fix.
  3. + 1 more questions in this round (sign up to unlock)
5

Behavioral / Leadership

10
  1. 8

    Τύπος · conflict resolution

    Tell me about a time you had a significant disagreement with an engineer or designer about a product decision. How did you approach it, and what was the outcome?
  2. 9

    Τύπος · ownership

    Describe a time you took ownership of a project or problem that was outside your direct responsibility. What motivated you, and what did you achieve?
  3. + 8 more questions in this round (sign up to unlock)

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Interview tracks at Iliad / Free

How Iliad / Free's DNA translates across functions. Pick your role.

SWEs are expected to demonstrate strong technical skills, especially in networking, infrastructure, and scalable systems, crucial for Free Mobile and Freebox services. They value problem-solvers who can build robust, efficient, and cost-effective solutions with minimal oversight.

Debugging

A Freebox router is intermittently dropping internet connections for users in a specific building. The logs show occasional 'DHCP lease renewal failures'. Debug this issue, identify potential root causes, and propose a fix.

Data Structures

Design a system to efficiently track and report the number of active mobile users within specific geographic regions (e.g., cities, neighborhoods) in real-time. Assume data streams from millions of devices.

+ 1 more

Unlock the Software Engineer grading rubric for Iliad / Free

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Compare Iliad / Free with other tech interviews

Same DNA, different bar. Browse the closest companies in our database and see how their loops differ.

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