Actually, I took this question from Matt Bishop's Introduction to Computer Security. The answer can be in any format but is preferred if it is short in points.

"The designers of the UNIX password algorithm used a 12-bit salt to perturb the first and third sets of 12 entries in the E-table of the UNIX hashing function (the DES). Consider a system with 224 users. Assume that each user is assigned a salt from a uniform random distribution and that anyone can read the password hashes and salts for the users.

What is the expected time to find all users' passwords using a dictionary attack?

Assume that eight more characters were added to the password and that the DES algorithm was changed so as to use all 16 password characters. What would be the expected time to find all users' passwords using a dictionary attack?

Assume that the passwords were eight characters long but that the salt length was increased to 24 bits. Again, the salts (and the corresponding algorithms) are known to all users. What would be the expected time to find all users' passwords using a dictionary attack?"