The client

A Web browser that sends a request for a server resource can be called a client.

The client communicates with the server over HTTP. Protocols refer to rules. It can be said that the Web is built on the HTTP protocol for communication.

The sender

Transport Layer (TCP)

It divides the data (HTTP request packets) received from the application layer, marks the serial number and port number of each packet and forwards the packets to the network layer.

Network Layer (IP protocol)

Add the MAC address as the communication destination and forward the MAC address to the link layer.

IP and IP address

IP is the name of a protocol

The FUNCTION of IP protocol is to send various packets to each other. Ensure that the IP address and MAC address are correct.

IP address Specifies the IP address assigned to a node

A MAC address is the fixed (physical) address of a NIC. IP addresses can be paired with MAC addresses. The IP address can be changed, but the MAC address is basically unchanged

The ARP protocol is used to communicate by MAC address

The communication between IP addresses depends on MAC addresses.

During the transfer, the MAC address of the next transfer device is used to search for the next destination. In this case, ARP is used.

The ARP protocol is used to resolve addresses. Based on the IP address of the communication, the CORRESPONDING MAC address can be detected.

TCP to ensure reliability

TCP is located at the transport layer and provides reliable byte stream services.

Make sure the data gets to the target

TCP uses the three-way handshake. (There are also various other means to ensure the reliability of communication)

DNS service responsible for domain name resolution

DNS provides the resolution service between domain names and IP addresses

Using an IP address to access it is very impersonal, but using numbers and letters that are easy for humans to remember makes it harder for computers to understand. To solve this problem, DNS service came into being.

The DNS provides the service of searching IP addresses by domain names or reverse-searching domain names from IP addresses.

The relationship between various protocols and THE HTTP protocol

URI

URI concept

A URI is a location identifier for a resource represented by a protocol scheme. A protocol scheme is the name of the protocol type used to access resources.

A URI represents an Internet resource as a string, and a URL represents the location of the resource on the Internet.

Visible urls are a subset of URIs.

URI format

Use HTTP: or HTTPS: to obtain the protocol type specified for accessing resources. Case insensitive, followed by ‘:’