Essential Python Backend Interview Checklist: Questions, Code & Tips

I have a background in communications and have worked less than two years on C++ MFC GUI development at a struggling state-owned research institute. Now I am seeking Python backend positions, mainly using the Django framework, and I want to share my interview experiences and lessons learned.

Interview companies: Two Beijing startups (40‑50 people each), Guokr (phone interview only), Zhihu (phone interview only), iQIYI (applied via Lagou), NetEase in Hangzhou (internal referral).

The biggest takeaway is to code every day and push code to GitHub consistently; maintaining a GitHub presence for at least five days a week over six months impresses interviewers.

Other observations: each company emphasizes different skills, and neglecting any area (the "weakest link" principle) can be fatal, as I experienced with iQIYI when I could not write code on the spot.

Python Syntax and Fundamentals

Topics to master:

Mutable vs immutable types

Shallow copy vs deep copy; implementing deepcopy __new__() vs __init__() differences

Common design patterns

Encoding/decoding basics

List comprehensions vs generators

Decorators and how to implement a singleton with them

Regular expression for email validation

Garbage collection: reference counting, generational, cyclic references

Multiprocessing vs multithreading; CPU‑bound tasks

Inter‑process communication methods

Coroutines and why they can be faster than threads

Difference between range and xrange Write a C function that converts an IP address string (e.g., "172.0.0.1") to a 32‑bit integer

Algorithm & Sorting

Implement quicksort and heapsort

Know time complexities of common sorting algorithms and quicksort’s average case

Given an unsorted list of length n, find all combinations with interval d and analyze complexity

Print all possible combinations of a list A = [A1, A2, …, An] One‑line Python to compute 1+2+3+…+10**8 Recursive palindrome check

Detect a cycle in a singly linked list

Sort a singly linked list using quicksort

Find the median of an unsorted numeric list and estimate its complexity

Traverse an unknown directory tree using two different priority traversal strategies

Network Basics

Identify which OSI layer TCP/IP belongs to

Explain long‑living socket connections

Differences between select and epoll TCP vs UDP; three‑way handshake and four‑way termination

Reasons for excessive TIME_WAIT states

Full HTTP request/response flow from client to server

GET vs POST and other HTTP methods

Concept of RESTful APIs

Common HTTP status codes (200, 403, 404, 504, etc.)

Database

Types of MySQL locks and how deadlocks occur

Reasons and methods for sharding and partitioning

Differences among CHAR, VARCHAR, and TEXT JOIN types and behavior of LEFT JOIN when the right table has no matching rows

Index types; B‑Tree vs hash index differences

Write a query optimization example

Basic knowledge of NoSQL, differences from relational databases, and common Redis data structures

Linux & Git

Common Linux and Git commands and their purposes

How to view current processes

Other frequently used command‑line tools

Django Project Topics

Briefly describe your project responsibilities, even if not backend‑focused

Identify the most challenging part of the project and your solution

Familiarity with Django admin source code and Flask source code; understanding of open source

MVT (Model‑View‑Template) architecture

Cache usage

Middleware purpose

CSRF protection in Django and XSS basics

Design a simple login flow

Session vs cookie, why sessions are considered secure

Roles of uWSGI and Nginx

If you can answer these questions confidently, you are ready to attempt junior web backend interviews. Good luck!

Additional resource: a well‑organized GitHub repository for Python interview preparation – https://github.com/taizilongxu/interview_python