Analysis: The whole process -http visit a page, it is like we enter the address in the address bar and click Enter access
The main test sites face questions are: TCP computer network / IP protocol stack
Photo: http request is first submitted to the application layer, the transport layer is transmitted by the encapsulation, the protocol TCP packet and the TCP header is HTTP data.
Then the network layer, the IP packet encapsulation, it is constantly dispensing data. Finally came the link layer, plus a transport protocol (Ethernet *) associated with a hardware,
Transmission media by the hardware, and then performing the unpacked data to the final HTTP.
Small knowledge: mainly in the application layer, transport layer and network layer, respectively corresponding to the three protocol
Application Layer: DNS Domain Name Service
Transport Layer: TCP to ensure reliability of data segmentation
Network layer: IP is responsible for transport
Test sites: 1 "request package unpacking
2 "describes the layers
3 "once to create multiple TCP requests
4 "browser cache (extra points)
Problem: that the whole process at http access a page? ? ?
Answer: URL URLs we entered in the application layer for DNS domain name resolution, and find its corresponding IP address.
And the requested data into the data to HTTP. The premise is to see whether there is a cache, if there is a cache, you can directly take
Take data, if no cache, it would need to be requested. In the transport layer using the TCP protocol for reliable transmission,
Plus the TCP header package. In the network layer plus the encapsulating IP header, to the server through the network layer. Then
Sequentially up (deblocked) find application layer, the data obtained. And then returned from the server to the client, the entire load
page.