What type of query is known as a query that keeps working until an answer of some kind is forthcoming?

If an optical disc will not eject using the eject button or through the operating system, a user can use a(n) _______ to insert into the emergency eject hole

Fill in the blank(s) with correct word

The computer handling incoming e-mail messages is known as the ____________________ e-mail server.

Fill in the blank(s) with the appropriate word(s).