It's going to be golden nine and silver ten soon , Xiaobian summed up some interview questions, including Baidu / tencent / millet / NetEase / sogou / You know / JD.COM /360/ Melon seeds , Now put it on , Because it's self-organizing , So if the coverage is not comprehensive, please understand .

According to my interview experience over the years , The interview has a certain level , Such as bat Every point of the company goes deep into , And some companies just ask the surface , Therefore, each field is divided into two parts that must be mastered and deeply understood .

One 、 computer network

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Base part

• TCP Header format
• UDP Header format
• TCP/UDP difference （ It's not just macro , It's better to explain clearly according to their own mechanism ）
• HTTP Status code （ It's better to combine the usage scenarios , For example, which one to use when cache hits ）
• HTTP agreement （ The function of some header fields , Such as cace-control、keep-alive）
• OSI agreement 、TCP/IP Protocol and the corresponding protocol for each layer .
• SESSION Mechanism 、cookie Mechanism
• TCP Three handshakes 、 Four waves （ This question really needs to be answered , But it's really the interviewer's favorite question , It's recommended to roll it every day , And it's not just the process of every request , Various FIN_WAIT、TIME_WAIT State should also be mastered ）.
• The process from opening a web page to displaying a page （ It covers all aspects ,DNS Analytic process ,Nginx Request forwarding 、 Connection establishment and retention process 、 Browser content rendering process , The more detailed you think, the better ）.
• http and https difference ,https Additional process at request ,https How to ensure data security
• IP Address subnet Division
• POST and GET difference
• DNS Analytic process

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In-depth part

• TCP How to ensure the reliable transmission of data （ This problem can lead to many problems , Congestion control starts slowly 、 Congestion avoidance 、 Fast retransmission 、 Sliding window protocol 、 Stop waiting for agreement 、 Timeout retransmission mechanism , It's better to master ）
• Address resolution protocol ARP
• The difference between switch and router

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Two 、 database

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Base part

• Four characteristics of transaction （ACID）
• Database isolation level , What is the problem with each level ,mysql Which level is the default
• MYSQL The difference between the two storage engines （ Business 、 Lock level and so on ）, Their applicable scenarios
• Database optimization （ from sql Sentence optimization and index are two parts of the answer ）
• The index has B+ Index and hash Indexes , The difference between them
• B+ Index data structure , and B The difference between trees
• Classification of indexes （ primary key 、 unique index ）, Leftmost prefix principle , When the index fails
• The difference between a clustered index and a nonclustered index .
• What locks are there （ Optimistic lock pessimistic lock ）,select How to lock it
• The difference between relational database and non relational database
• understand nosql
• Three paradigms of database , Design a data table based on a scenario （ You can do it by hand ER chart ）
• Master-slave replication of database
• Use explain Optimize sql And index
• long_query How to solve
• Internal connection 、 External connection 、 Cross connect 、 Cartesian product, etc

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thorough

• MVCC Mechanism
• According to the specific scene , Explain the version control mechanism
• How to solve deadlock
• varchar and char Usage scenarios of .
• mysql How to solve the problem of concurrency （ Through transaction 、 Isolation level 、 lock ）

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Redis

• redis What are the data structures
• redis Queue application scenario
• redis and Memcached（ Support data persistence ）
• Distributed usage scenarios （ Store session etc. ）
• Release / Subscribe to usage scenarios

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3、 ... and 、 operating system

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• Memory page replacement algorithm
• Process scheduling algorithm
• Interprocess communication mode
• Process thread difference
• Communication between processes
• Father child process 、 Orphan process
• fork Process operation ,

I didn't give a good answer to this part , It's just rote learning , It is suggested that students with good foundation should take a look at the operating system , It's a big bonus .

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Four 、 Algorithm

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Basics

• The finger of the sword OFFER The most common topics are , Even if it's not the original title, it's a variation of the title , Because an interview is not like a written test , Generally, there are no particularly difficult problems , So the sword finger OFFER Small and precise topics are very suitable for . I suggest you brush it by hand .PHP Students can refer to the column Jianzhi OFFER
• Binary tree correlation （ Level traversal 、 Seek depth 、 Find the distance between two nodes 、 Flip binary tree 、 Traversal in front, middle and back order ）
• List related （ Insert node 、 Linked list location 、 Use linked list to add and subtract big numbers , Bidirectional linked list to achieve the queue 、 Looking for links in a linked list ）
• Pile up （ Looking for the biggest... In a lot of data N A number, almost every time , And then there's the adjustment of the heap when it's inserted ）
• Sort （ Eight sorts , Their time complexity 、 Stability of sorting algorithm . Fast line asks almost every time ）
• Two points search （ They usually go deep into , If you look for an array, the sum is K Two numbers of ）
• Two stacks implement queues .
• chart （ Depth breadth first traversal 、 Single source shortest path 、 Minimum spanning tree ）
• Dynamic programming problem .

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thorough

• The nature of the mangrove
• The difference between divide and conquer and dynamic programming
• Time complexity of calculation
• The time complexity of binary tree and hash table lookup
• Stack and linked list are tools often used in interview algorithm , Think more about how to use the nature of the data structure
• solve , Because an interview is not like a written test , Pay more attention to the basic data structure , The general problem is relatively simple . Then take the mold is also a common tool （ For example, I once asked how to make 100 Processes are called with specified weights , You can take the mold ）.
• Interviewers usually ask simple questions first , And then go deep , It's better to follow his ideas , Because the ability to understand his hints also needs to be investigated .
• LINUX
• The difference between hard link and soft link
• kill usage , The reason why a process can't be killed （ Go into kernel state , Ignore kill The signal ）
• linux Used orders
• System management command （ For example, check the memory usage 、 Network situation ）
• Use of pipes |
• grep Use , Be sure to master , Every time I ask you to look up
• shell Script
• find command
• awk Use
• The language part （PHP）
• Array operation function
• String manipulation functions （ Array and string functions are the most frequently asked , A lot , Don't mix it up ）
• Pointer and reference are different
• The difference between heap and stack
• == === difference
• PHP Garbage collection mechanism
• zval structure
• prevent sql Inject
• Cross-domain problem
• Long links and long polling

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object-oriented 、 Design patterns

• Interface is different from abstract class
• Single inheritance
• construct Call order of （ Between subclasses and superclasses ）
• Design patterns （ Factory mode 、 The strategy pattern 、 The singleton pattern 、 Decorative patterns are common ）
• OOP characteristic , Through which mechanisms
• The difference between rewriting and overloading
• Static class static method
• Design a class according to a requirement （ We mainly consider the inheritance relationship between classes and the permission setting of properties ）

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project

• Difficulties encountered in the project （ Think ahead , And explain the implementation or optimization methods ）
• The magnitude of the system 、pv、uv etc.
• Solutions to high concurrency （ Distributed ）
• What are the main responsibilities in the project .
• nginx Load balancing of
• Consistency of Distributed Cache , How to expand the server capacity （ Hash loop ）

In a word, you should be familiar with the project part of your resume , Technology stack 、 Project functions 、 All difficulties should be considered .

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The following is the interview topic of some Internet companies' full stack knowledge points sorted out by Xiaobian himself , It's not too complete. Please understand .

Interview topics of major factories

• computer network （ Both documents summarize ）

• operating system

• The basic chapter

• JVM piece

• Multithreading & Concurrent articles

• Spring piece

• MyBatis piece

• SpringBoot piece

• MySQL piece

• Redis piece

• Nginx piece

• MQ piece

• Data structure and algorithm

• Linux piece

• Resume