I've been reading HTTP books recently, and it's a bit slow and intermittent, and I forget a lot of things after reading them. The knowledge points are many and scattered, and I feel that I have to read it several times to digest it.
The TCP/IP protocol family is divided into 4 layers according to the layers:
Application layer:
The application layer determines the activities of communication when providing application services to users.
Transport layer:
The transport layer provides the application layer with data transfer between two computers in a network connection.
Network layer:
The network layer is used to process packets flowing on the network.
link layer:
The link layer handles the hardware part of connecting the network.
TCP/IP communication transport stream:
IP protocol:
The role of Internet Protocol is to transmit various data packets to the other party. There are two conditions (MAC address and IP address) to ensure that the data can be accurately transmitted to the other party.
MAC address:
The fixed address to which the network card belongs.
IP address:
Indicates the address to which the node is assigned.
TCP three-way handshake:
In order to accurately transmit data to the target, the TCP protocol uses a three-way handshake mechanism. The sender first sends a data packet with the SNY (synchronize) flag to the other party. After the receiver receives it, it will return a data packet with the SYN/ACK (acknowledgement) flag to confirm receipt, and then the sender sends another A packet with an ACK flag indicates that the handshake is over. Note: If the handshake process is interrupted at a certain stage, the TCP protocol will send the same packets again in the same order.
DNS service:
Computers have IP addresses, host names and domain names (such as www.cnblogs.com). Users usually use domain names to access instead of IP addresses, because domain names are more in line with human memory habits than a string of numbers in IP addresses, but computers are very Difficult to understand the name, so the DNS service came into being.
Finally, take a look at an overview map:
All the above pictures are from Nobu Ueno's "Illustrated HTTP" ("Let's Learn HTTP Together Tonight").