Answer:
When you need to keep the original document or send the document to multiple people.
Explanation:
If you need to keep the original document (eg. marriage documents or birth certificate or something important), you would make a copy of it (unless you are sending it to a lawyer or a government agency).
If you, for instance, have a memo for your company that all your employees need to read, you would copy the document so you would be able to print it and send it to everyone without passing the document one at a time.
 
        
             
        
        
        
Answer:
Answered below
Explanation:
Redis provides a short structure representation for the Sets data structure, called Intset. 
Intsets reduce the data size and presents short sets as a sorted array of integers. This provides an advantage of fast performance during sets operations and also low overhead.
Redis always uses inset representation so long as the set size is smaller than the configured size.
 
        
             
        
        
        
Answer:
The text will be shown without any formatting.
Explanation:
 
        
                    
             
        
        
        
ISO it is an organzation for agreement on internationational of network communication worldwide
OSI is the model for understanding and designing a network architecture