TCP and UDP are provided port addressing .
UDP is an unreliable, connectionless protocol, there is no connection management capabilities, is not responsible for resending messages lost or erroneous data, there is no flow control function.
IP to MAC = ARP; RARP is in turn
In the browser, enter the URL, and press Enter
Browser to the DNS server issue DNS request and obtain results
According to the destination IP address and port number, and server establish a TCP connection
The browser to the server transmits the data request
Server web page data is sent to the browser
The browser parses the received data and displays
Communication is completed, disconnect TCP connections