Can you please help on number 1 and 2?

Is an attack that relies on guessing the isns of tcp packets

Explain how email technologies enable the exchange of messages between users. find out the typical parts of an email address and explain each part.

Match the following errors with their definitions. a. #name b. #value c. #ref d. 1. when a formula produces output that is too lengthy to fit in the spreadsheet cell 2. when you enter an invalid cell reference in a formula 3. when you type text in cells that accept numeric data 4. when you type in a cell reference that doesn’t exist