2024-07-11
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introduce
In the process of learning computer networks, I have sorted out some key points that may be tested in the exam. Some specific points may not be covered. I hope it will be helpful to everyone!
Address resolution, converting domain names into IP addresses
Recursive query
Iteration query
Based on TCP, because file transfer cannot be error-prone
Castrated version, using UDP datagram, only supports file transfer but not interaction
Also known as terminal emulation protocol, it is not complicated to implement and is rarely used now.
TCP connection is used, and NVT format is used in the middle to convert user key input, etc. The target end can then convert it into the format required by the corresponding system
Large-scale, online information repository
That is, a site is linked to another site using distributed
Application: For example, if you click on the underlined blue word, you will jump to another web page
Without the World Wide Web, users would have to use complex commands to navigate, rather than click directly on links.
The World Wide Web is a distributed hypermedia system, an extension of the hypertext system that includes sound, images, etc.
Tagging different documents on the World Wide Web
Use TCP connection, but HTTP itself is connectionless, that is, there is no need to establish an HTTP connection before exchanging HTTP messages
Stateless, the browser does not remember how many times the user has visited or what content they have visited, and the response is the same for each visit
Proxy Server
A layer of cache is added in the middle. If there is data in the cache, it will be responded to the client directly without having to access the resource on the Internet.
HTTP message structure
1. Start the row
2. Header line
3. Entity Subject
Tips: Status codes include
- 200 ok
- 304 Redirect
- 400 Client Error
- 500 Server error, etc.
Simply put, it is a web page
Closely related to front-end knowledge, I have learned somehtml css js Everyone knows what it is, and there is a lot of information on the Internet, so I won’t introduce it in detail here.
Search engine: a tool used to search the World Wide Web (full-text search, classification search)
Blog is a sharing of personal documents and diaries
Weibo is a microblog that only records trivial fragments and answers a question.
facebook、youtube、tiktok …
Simple Mail Transfer Protocol SMTP
Internet Text Message Format RFC
SMTP protocol usage TCP As its transport layer protocol
supply Plug and Play Networking Mechanisms
When a computer joins a network, it is automatically assigned an IP address.
Each network now has at least one DHCP relay agent
Management programs, processes, etc.
Issued when the application process needs to use the network to communicateSystem calls, requesting the operating system to create a **"socket"** for it so that the system resources required for network communication can be allocated to the application process.
The operating system represents the sum of these resources with a number called a socket descriptor.
All network operations performed by the application process must use this socket descriptor.
After the communication is completed, the application process notifies the operating system to reclaim all resources associated with the socket descriptor through a system call to close the socket.
When an application process needs to communicate using the network, it issues a system call.
Using the TCP/IP application programming interface API, you can write Internet-based network applications.
When calling the API, users can use TCP services or other services such as UDP.
TCP provides a connection-oriented service.
Using TCP services requires three stages:
Involving file upload and download
P2P software is software that uses the P2P principle to achieve high-speed downloading, such as: Thunder
I have devoted myself to the research of technology for more than 30 years. I am proficient in various languages such as Java, Linux, JavaScript, PHP, CSS, etc. I have made many contributions in the field of open source. I have established a developer documentation site to share some problems in technology development for everyone to read.
