1. If the bit string 01111011111101111110 is subjected to bit stuffing, what is the output string?

a. 011110111110011111010 c 011110111010011111010

b. 011110111110111111010 d 011111111110011111010

2. The following data fragment occurs in the middle of a data stream for which the character-stuffing algorithm described in the class is used: DLE, STX, A, DLE, B, DLE, ETX. What is the output after stuffing? (DLE=Data Link Escape, STX= start of TeXt and ETX=End of TeXt).

a. DLE, STX, A, DLE, DLE, B, DLE, DLE, ETX

b. DLE, DLE, STX, A, DLE, DLE, B, DLE, DLE, ETX

c. DLE, DLE, STX, A, DLE, B, DLE, ETX

d. DLE, DLE, STX, A, B, DLE, DLE, ETX

3. A channel has a bit rate of 4 kbps and a propagation delay of 20 msec. For what range of frame sizes does stop-and-wait give an efficiency of at least 50%?

a. 100 bits c. 160 bits

b 200 bits d. 60 bits