HTTP protocol, TCP protocol, IP protocol, DNS service before the relationship and differences

There has been a problem for a long time, everyone is talking about the HTTP protocol, TCP protocol, IP protocol, what is the difference between them, what is the use, no one told me, recently read this "illustrated http" understand some of the film from the book

First, understand a transmission stream to expand

For example, HTTP is the first client in the Application layer (HTTP protocol) to send an HTTP request to see a Web page.

Then, for the convenience of transmission, the data received from the Application layer (the HTTP request message) is segmented at the Transport Layer (TCP protocol ), and tagged serial number and port number are forwarded to the network layer on each message.

On the Network layer (IP protocol), increase the MAC address as the destination of the communication and then forward to

。 In this way, the communication request to the network is ready to complete.

The receiving end server receives the data at the link layer and sends it sequentially to the upper layer, until the application tier. When transferred to the application tier, it is true that HTTP requests sent by the client are actually received.

Ii. protocols that are closely related to http: ip,tcp and DNS

IP protocol : From this, you can know that the IP protocol belongs to the network layer, may be someone will confuse the "IP" and "IP Protocol", "IP" is actually a name of the protocol, the role of IP protocol is to send various packets to each other. and to ensure that they do transfer to each other, you need to meet all kinds of conditions. Two important conditions are IP address and MAC address
The IP address indicates that the address is assigned, and the MAC address refers to the fixed location where the network card belongs, the IP address can be transformed, but the MAC address is basically unchanged

TCP protocol : According to the level of the TCP protocol is located in the transport layer, providing a reliable byte stream service, the word throttle service refers to the convenience of transmission, the large chunks of data into the message segment unit for the management of packets.

DNS: The DNS service is the protocol that is located at the application layer of the HTTP protocol, which provides parsing services between domain names to IP addresses

Here's a diagram of how the IP protocol, the TCP protocol, and the DNS service play a role in communicating with the HTTP protocol

HTTP protocol, TCP protocol, IP protocol, DNS service before the relationship and differences