
<u>Networks were originally used as a government weapon 61 years ago</u> to <u>communicate information</u> such as data and research. However, individual networks were eventually discontinued by the government and made open to the public to use for things such as PAN, LAN, MAN, WAN, SAN, and so on.
<u>Our internet today is capable of communicating with bilions of computers.</u> This is possible due to your modem using radio wave-like speeds to connect to your ISP. Your ISP then connects to a larger network, which is connecting to thousands of other networks. You see, <u>the internet is just a large network of networks that are connected through very fast radiowaves</u>. However, it is not just a single network being used anymore; it's thousands of them. The term, "internet" was used to describe this large selection of networks. In short, <u>B</u><u> would be incorrect. </u>
The worldwide web is a protocol used by the internet to connect to select websites favourably from whoever's using it. This obviously would not define the network, as this is something that's used by it. Furthermore, <u>A</u><u> would not be correct.</u>
As described already, the network was a selection of computers used to communicate information to each other. <u>C </u><u>would not be correct </u>as it states that there is only one computer being used.


Web-based application - this is a special kind of applications that operate in the global Internet via HTTP. The user interacts with the program, usually carried out through the browser.
Answer:
We need context, it could be several answers
Explanation:
For the view of Exercise 4.18, explain why the database system would not allow a tuple to be inserted into the database through this view.
For reference
For the database of Figure 4.12, write a query to find the ID of each employee with no manager. Note that an employee may simply have no manager listed or may have a null manager. Write your query using an outer join and then write it again using no outer join at all.
OUTER JOIN
select e.ID from employee e left outer join manages m on e.ID = m.ID
where m.manager_id is null;
NO OUTER
select e.ID from employee e where e.ID not in (select m.ID from manages m) or e.ID in (select m.ID from manages m where m.manager_id is null);