1. Application layer

2. Transport layer

3. Network layer

4. Network interface layer

Table link [URL]

Simple Mail Transfer Protocol [SMTP] Post Office Protocol [POP] Internet Mail Access Protocol [IMAP]

The range of each group of decimal numbers is 0~255

IPv6 solves the problems in IPv4 such as end-to-end IP connection, security, multicast, Issues such as mobility and plug-and-play.

The hierarchical structure of domain names is as follows: n-level domain name...third-level domain name. second-level domain name. top-level domain name

The domain name of People's Posts and Telecommunications Publishing House is: www.ptpress.com.cn The top-level domain name is cn (representing China), and the second-level domain name is com (representing commercial organizations) The third-level domain name is ptress (representing People’s Posts and Telecommunications Publishing House) www indicates that this domain name corresponds to the World Wide Web service

Physical network is the basis of network communication

client

Application layer

data layer

client

Service-Terminal

Simplicity

Scalability

platform independence

Relational Database

network database

hierarchical database

model: IaaS, PaaS, SaaS

With virtualization, ultra-large scale, high scalability, High reliability and low cost advantages

Big data refers to data that cannot be captured within a certain time range using conventional software tools. Collection of data managed and processed Requires the use of distributed processing, distributed databases, cloud storage and virtualization technologies of cloud computing

AR includes multimedia, 3D modeling, real-time video display and control, New technologies such as multi-sensor fusion, implementation tracking and registration, scene fusion, etc.