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==== What is NGINX? Nginx is a lightweight/high performance reverse proxy Web server, it is very efficient reverse proxy, load balancing, it can handle 20-30,000 concurrent connections, official monitoring can support 50,000 concurrent.

==== Why use Nginx? Cross-platform, simple configuration, directional agent, high concurrent connection: handle 20-30,000 concurrent connections, and the official monitoring can support 50,000 concurrent connections. Nginx handles static files well and consumes less memory. In addition, Nginx has built-in health check function: if one of the servers is down, a health check will be done, and requests sent again will not be sent to the server that is down. Resubmit the request to another node. With Nginx you can also:

  1. Save broadband: support GZIP compression, can add browser local cache
  2. High stability: the probability of downtime is very small
  3. Receiving user requests is asynchronous

==== Why is Nginx performing so well? Because its event handling mechanism: asynchronous non-blocking event handling mechanism: using the EPOLL model, provides a queue, queuing resolution

==== How does NGINX handle requests? When NGINX receives a request, it matches the server module with the LISTEN and SERVER_NAME directives and the location in the server module. The location is the actual address of the server {#, which starts with the first server block. Represents a standalone web hosting site listen 80; Default 80 server_name localhost; # host name of the domain name provided by the service location / {

The first Location block starts

The root HTML; Index.html index.htm = index; index.html = index; # default home file, multiple separated by space} # result of first location block}

==== What are forward and reverse proxies? (key) 1) positive agency client is true, is a located in the client and server, before the original server to get content from the original server, the client send a request to the agent and specify the target (the original server), then transfer agent to the original server requests and will be returned to the client, the content of the The client can use the forward proxy. For example, we want to visit a website, we can not access directly, then we can find a proxy server for our service, we request to this website through the proxy server. For this website, he only knows that a server has visited him, he does not know that you have visited him.

2) The reverse proxy is hidden in the real server. The reverse proxy server is located between the user and the target server, but for the user, the reverse proxy server is equivalent to the target server, that is, the user can directly access the reverse proxy server to obtain the resources of the target server. At the same time, the user does not need to know the address of the target server, and does not need to make any Settings on the client side. Reverse proxy servers are often used as Web accelerators, where a reverse proxy is used as a front-loader on the Web server to reduce the load on the network and server and improve access efficiency. Reverse proxy means that the proxy server receives the connection request on the Internet, and then forwards the request to the server on the internal network, and returns the results obtained from the server to the client that requests the connection on the Internet. At this time, the proxy server behaves as a node server.

==== What are the advantages of using a reverse proxy server? A reverse proxy server can hide the existence and characteristics of the source server. It acts as an intermediary between the Internet cloud and the Web server. This is great for security, especially if you are using Web hosting services.

==== The pros and cons of Nginx? Advantages:

  1. Small memory, can achieve high concurrent connection, fast processing response
  2. Can realize HTTP server, virtual host, reverse proxy, load balancing
  3. Nginx is simple to configure
  4. Can not expose the formal server IP address shortcomings: dynamic processing is poor: NGINX static file processing good, less memory consumption, but the processing of dynamic pages is very chicken ribs, now the general front end with NGINX as a reverse proxy to resist pressure

====Nginx application scenarios?

  1. HTTP server. Nginx is an HTTP service that provides HTTP services independently. Can do web static server.
  2. Virtual hosting. Can achieve in a server virtual out of a number of websites, such as the virtual machine used by personal websites.
  3. Reverse proxy, load balancing. When the site visits to a certain extent, a single server can not meet the user’s request, the need to use multiple server cluster can use NGINX to do the reverse proxy. And multiple servers can share the load evenly, not because of a server load high downtime and a server idle situation.
  4. Nginx can also configure security management, for example, you can use Nginx to build API interface gateway, to intercept each interface service.

==== What is the directory structure of Nginx? (key)

│ ├─ Anti-Flag – Anti-Flag – Anti-Flag – Anti-Flag – Anti-Flag – Anti-Flag – Anti-Flag – Anti-Flag │ ├─ FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI – FastCgi_Params # FastCGI │ ├─ types.default │ ├─ Bass Exercises – Bass Exercises – Nginx.conf. Defaults │ ├─ Bass Exercises – Nginx.conf │ ├─ Bass Exercises – – Bass Exercises – – Win-UTF ├─ Bass Exercises – – Bass Exercises – – Win-UTF ├─ Bass Exercises – – Bass Exercises – – Bass Exercises # fastcgi_temp # fastcgi Temporary Data Directory – HTML # Nginx default site directory – 50x. HTML # error page instead of displaying files │ ├─ Exercises – Logs # Nginx – Access. Log # │ ├─ Exercises – Error. Log # error └─ nginx.pid # pid file, nginx process start, ├─ Anti-Flag – Proxy_temp # temp – Sbin # Nginx command directory ├─ Anti-Flag – SCGI_TEMP # temp – uwsgi_temp # temporary directory

==== What are the properties of the nginx.conf configuration file? Nginx.conf consists of several blocks. The outermost block is main, which contains Events and HTTP, which contains upstreams and servers, which in turn contain locations

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