1. URL Which parts are included , What are the functions of each part ？
A complete URL= agreement + Domain name or IP+ Port number + route + Query string + Anchor point .
give an example ：www.baidu.com/s?wd=hello&…
2. DNS What is the role of ,nslookup How to use the order ？
DNS (Domain Name System) The domain name system , It's a hierarchy 、 Decentralized Internet Connect resource naming system .DNS Maintain a domain name and corresponding resources, such as IP List of addresses .
DNS The most prominent function is to make the domain name easy to remember ( for example mozilla.org) Translation becomes Digital IP Address ( for example 151,106,5,172). This one goes from domain name to IP The mapping process of address is called DNS Inquire about (DNS lookup), With the corresponding ,DNS Reverse query (rDNS) Used to find and IP The domain name corresponding to the address .
nslookup command Used to query DNS The record of , Check whether domain name resolution is normal , It is used to diagnose network problems when the network fails . Its usage is as follows ：
nslookup domain [dns-server]
nslookup -qt=type domain [dns-server]
among ,type It can be of the following types ：
nslookup –d [ The other parameters ] domain [dns-server]
Just at the time of inquiry , add -d Parameters , You can query the domain name cache .
3. IP What is the role of ,ping How to use the order ？
IP Address （ English ：IP Address, Full name Internet Protocol Address）, Internet protocol address 、 Internet protocol address . When the device is connected to the network , The device will be assigned a IP Address , Used as a sign . adopt IP Address , Devices can communicate with each other , without IP Address , We will not be able to know which device is the sender , There is no way to know which recipient is .IP Address has two main functions ： Identify the device or network and Addressing （ English ：location addressing）.
ping The command is used to detect the host .
perform ping Command will use ICMP Transfer protocol , Send a message asking for a response , If there is no problem with the network function of the remote host , They'll respond to the message , So we know that the host is working normally .
ping [-dfnqrRv][-c< Number of completions >][-i< Seconds apart >][-I< Network interface >][-l< Load ahead >][-p< Template Styles >][-s< Packet size >][-t< Survival value >][ Host name or IP Address ]
4. What is domain name , What kinds of domain names are there ？
Domain name （ English ：Domain Name, abbreviation ：Domain）, Hereinafter referred to as a domain name 、 domain , Is the name of a computer or computer group on the Internet consisting of a string of dot separated characters , Used to identify the electronic orientation of the computer during data transmission . Domain name can be said to be a IP Address , The purpose is to remember the latter .
There are three main categories of domain names ：