Top 150 Must‑Know Linux & DevOps Interview Questions (Answers Inside)

Disk usage detection (using a shell script)

What load‑balancing strategies does LVS provide?

Explain your understanding of LVS.

What is the principle of load balancing?

What two components make up LVS?

What terminology is related to LVS?

Principle of LVS‑NAT mode

Characteristics of the LVS‑NAT model

Principle of LVS‑DR mode

Characteristics of the LVS‑DR model

Comparison of the three LVS load‑balancing modes

LVS scheduling algorithms

Differences between LVS and Nginx

What are the functions of load balancing?

Nginx load‑balancing distribution strategies

What is keepalived?

How do you understand the VRRP protocol?

How does keepalived work?

Causes of split‑brain (brain split) in keepalived

How to solve keepalived split‑brain issues?

How does Zabbix monitor split‑brain?

What load‑balancing strategies does Nginx implement?

Which Nginx modules are used for load balancing?

What are the various implementations of load balancing?

How does Nginx achieve layer‑4 load balancing?

What web services do you know?

Why use Nginx?

Why is Nginx performance higher than Apache?

Components of epoll

Differences between Nginx and Apache

Advantages and disadvantages of Tomcat as a web server

Three Tomcat ports and their purposes

Differences between FastCGI and CGI

Common Nginx commands

What is a reverse proxy, a forward proxy, and their differences?

Differences among Squid, Varnish, and Nginx

How does Nginx handle HTTP requests?

What virtual host configurations does Nginx support?

How does Nginx perform health checks on backend services?

Differences between Apache Worker and Prefork models

Default Tomcat port and how to change it

Tomcat operating modes

Request flow inside Tomcat

How to monitor Tomcat memory usage

Optimizations you have performed on Nginx

Optimizations you have performed on Tomcat

How to handle Nginx session desynchronization

Common Nginx modules

Common Nginx status codes

Process of accessing a website

TCP three‑way handshake and four‑way termination

Definition of dynamic vs. static resources

Maximum concurrent connections supported by a worker

Differences between Tomcat and Resin and selection criteria

What is gray‑scale release for websites?

How to analyze Nginx access logs to find top‑10 IPs by page views

Differences among Nginx versions

New versions of Nginx

Interview questions about Nginx access module

Default Nginx configuration file

Location directive rules

How to configure anti‑hotlinking in Nginx

Differences between DROP, DELETE, and TRUNCATE

MySQL master‑slave architecture

Problems in MySQL master‑slave replication

Methods of MySQL replication

Causes and solutions for master‑slave lag

How to detect master‑slave delay

How to recover a lost MySQL root password

MySQL backup methods

Features of InnoDB

Difference between VARCHAR(100) and VARCHAR(200)

Main types of MySQL indexes

Typical NoSQL database products, characteristics, and use cases

How to strengthen MySQL security with concrete measures

Binlog working modes, characteristics, and enterprise selection guidance

Manual recovery steps when a replica in a one‑master‑multiple‑slave setup fails

At least five differences between MyISAM and InnoDB

How to troubleshoot a slow website caused by database performance, with examples

Principles of XtraBackup backup, incremental backup, and recovery; how to recover from accidental DROP using XtraBackup

How to perform master‑slave data consistency checks

How many types of MySQL logs exist?

Different binlog entry formats and their differences

How to handle MySQL CPU usage spiking to 500%

Is Redis single‑threaded or multi‑threaded?

Common Redis versions

Typical Redis use cases

Common Redis data structures

How Redis persistence is implemented

Principle of Redis master‑slave replication

Principle of Redis Sentinel mode

Differences between Memcached and Redis

Architectural patterns of Redis

What is a cache avalanche?

What is cache penetration?

What is cache breakdown?

Why is Redis so fast?

Use cases for Memcached

Features and working principle of Memcached service

How does Memcached perform authentication?

What is MongoDB?

Advantages of MongoDB

MongoDB use cases

In Kafka, what do ISR and AR represent, and what does ISR scaling mean?

Role of a broker in Kafka

Purpose of Zookeeper in Kafka and whether Kafka can run without it

How a Kafka follower synchronizes data with the leader

Why Kafka is so fast

Possibility of message loss or duplicate consumption in Kafka

Why Kafka does not support read‑write separation

What is a consumer group?

Kafka terminology overview

Typical scenarios where Kafka is applied

Kafka write process

Components of Zabbix

Two monitoring modes of Zabbix

Workflow of a monitoring system

Zabbix worker processes

Common Zabbix terminology

How to implement custom discovery in Zabbix

WeChat alert integration

How to batch‑install Zabbix agents

How Zabbix achieves distributed monitoring

Use cases for Zabbix proxy

Working principle of Prometheus

Prometheus components

ELK workflow

Input sources for Logstash

Logstash architecture

Key concepts of the ELK stack

Common Elasticsearch plugins

Parameters you monitor with Zabbix

MySQL synchronous and semi‑synchronous replication

CI/CD concepts

Kubernetes monitoring metrics

How Kubernetes performs log monitoring

Difference between Service and Ingress in Kubernetes

Overview of Kubernetes components

Fundamentals of the TCP/IP protocol

Understanding of CDN technology