计算机英语讲课笔记10

I. IP - Hostname Mapping

• We can access a network resource in two manners - using IP or using hostname
• URL (Uniform Resource Locator) is used to access a certain resource on the Internet.
• URL has four parts: protocol + host + port + path

1. Using IP Address

• Visit Hadoop WebUI：http://192.168.1.101:50070/dfshealth.html#tab-overview
  

2. Using Hostname

• Visit Hadoop WebUI：http://master:50070/dfshealth.html#tab-overview

3. Mapping Between IP and Hostname

(1) Windows

• hosts文件位置：C:\Windows\System32\drivers\etc\hosts
  

(2) Linux (CentOS)

• three nodes: master, slave1, slave2
  
  
  
• on the master, we want to ping slave1 in two manners
  
  
• We can do this in two manners because we have set the mapping between ip and hostname
• Execute the command: vim /etc/hosts
  

4. Hostname

(1) Display Hostname

• Execute the command: hostname
  

(2) Modify Hostname

• Execute the command: hostnamectl set-hostname howard-master
  
• Let’s view the new hostname
  
• Now let’s reboot the master virtual machine
  
  
• on the slave1, we ping master virtual machine by ip address
  
• on the slave1, we ping master virtual machine by the new hostname
  
• on the slave1, we can ping master virtual machine by the old hostname
  
• Now I want to restore the hosname of the master virtual machine
  
• reboot the master virtual machine
  
• reconnect the master virtual machine
  

II. Data Visutalization

• Let’s visit wikipedia: https://www.wikipedia.org/
  

• Click English hyperlink
  

• Enter data visualiztion in the search box

• URL: https://en.wikipedia.org/wiki/Data_and_information_visualization
  

• Task 1. Use Excel to make the table for the number of articles in different languages and then generate a pie chart for the data.

• Task 2. Use Echarts to make a pie chart for the data.

• Task 3. Use matplotlib to make a pie chart for the data.

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