Question

Networks

Hi guys. I need some assistance with a few questions below.

1. Which of the following is TRUE regarding a TCP 3-way handshake.
a.   Consists of 3 segments being sent between 2 hosts      
b.   Segments only carry data in the SYN, ACK and sequence number bits and bytes with no data      
c.   No ACK is needed for the SYNACK received from the receiver      
d.   A, B and C      
e.   None of the above

2. Which of the statements listed is true for the following scenario? A sending host sends a segment to a receiving host with the following 16-bit words: 0011 1101 1111 1110, 1110 1000 1111 1101 and 0001 0010 0111 0101. The receiving host receives the following 16-bit words: 0011 1101 1111 1101, 1110 1000 1111 1110 and 0001 0010 0111 0101.
a.   No error exists as no errors occurred in the transmission.      
b.   Bit swapping occurred in 2 of the 16-bit words therefore an error will be detected.
c.   Bit swapping occurred in corresponding positions in 2 of the 16-bit words therefore no error has actually occurred and no error will be detected      
d.   Bit swapping occurred in corresponding positions in 2 of the 16-bit words therefore when the checksum is added to the sum of the 16-bit words received, an error will be detected      
e.   None of the above

3. In which protocol does each packet have a timer?
a.   RDT3.0      
b.   Go-Back-N      
c.   Selective Repeat      
d.   A, B & C      
e.   None of the above

4. How is a UDP socket fully identified?
a.   Destination IP address and source IP address      
b.   Destination IP address and destination port number      
c.   Source port number and destination port number      
d.   Destination port number and source port number      
e.   None of the above

5. Why does UDP provide error checking using a checksum when link layer protocols already provide error checking?
a.   Not all link layer protocols provide error checking      
b.   A bit error could be introduced when the segment is being stored in the routers memory      
c.   Link by link reliability is not guaranteed      
d.   A, B and C      
e.   None of the above

Kindly assist.

Thank you

Answer 1

1. option (a) is correct.
   • 3 segments are sent over during the communication
   • couldn't understand the second option
   • An acknowledgment frame is sent after the SYNACK Is received
2. option (e) is correct
   • the last two bits of the first two words are swapped, hence an error occurred
   • it depends upon the algorithm used to detect an error, the checksum will not be able to detect the error
   • after the error occurred, the combination of the last four bits seemed to swap with each other.
3. option (b) is correct
   • no explanation is required
4. option (b) is correct
   • no explanation is required
5. option (e) is correct
   • error checking is an inherent feature of the data link layer
   • no error occurs when segments are in the router
   • UDP provides end-to-end reliability