<span>If a user name can have seven letters (with no distinction between upper and lower case), and if a letter can be repeated, then the maximum number of names is 26x26x26x26x26x26x26, or 8,031,810,176. That is, slightly more than eight billion names are possible.</span>
        
             
        
        
        
Answer:
ARPANET
Explanation:
It was the ARPANET sponsored by the US Department of Defense to enable scientists collaborate on research.