Cis105 questions need in a couple hours (8)

#4. Determine the total time it takes to transmit an uncompressed grayscale image (with 8 bits/pixel) from a screen with a resolution of 1,280 × 840 pixels using each of the following media:

a. A 56 Kbps modem

b. A 1.5 Mbps DSL line

c. A 100 Mbps Ethernet link




#5. Assume that we need to transmit a 1,440 × 900 uncompressed color image (using 16 bits per color pixel) over a computer network in less than 0.01 second. What is the minimal necessary line speed to meet this goal?


#20. What are the advantages of breaking up a single logical message into a number of fixed-sized packets and then sending each one of those packets independently through the network?


#1. The following are three possible logon scenarios. Explain why answer (c) below is preferable in terms of system security.

a. Welcome to XYZ computing / Enter username: jones / Invalid username / Enter username:

b. Welcome to XYZ computing / Enter username: smith / Enter password: password / Invalid access / Enter username:

c. Enter username: smith / Enter password: password / Invalid access / Enter username: smith / Enter password: FpQr56 / Welcome to XYZ computing 




#16. If a message is encrypted using AES with a key length of 256 bits, the brute force approach to decryption involves generating each of the 2256 possible keys in turn until one is found that decodes the encrypted message. Quantum computing was discussed in Chapter 5. Using a quantum computer, how many qubits are required to represent all 2256 possible keys simultaneously?




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