CSCE 41 6 Q#2

suppose host A send 3 TCP segments back to back to host B over a TCP connection. the sequence numbers of the 1st, 2nd and 3rd segments are 1000, 1500 and 2500 respectively. suppose 1st segment arrives, 2nd segment is lost, and then the 3rd segment arrives at B. when the 3rd segment arrives at B, in the ACK that B sends to A, what will be the ACK number? a. 1500 b. 1001 c. 1000 d. 2500

a. 1500

suppose host A send 3 TCP segments back to back to host B over a TCP connection. the sequence numbers of the 1st, 2nd and 3rd segments are 1000, 1500 and 2500 respectively. when the 1st segment arrives at B, in the ACK that B sends to A what will be the ACK number? a. 1500 b. 1000 c. 1001 d. 1501

a. 1500

suppose the congestion window of a TCP sender was 4 segments long and it receives 3 duplicate acks. after that, what would be the new threshold? a. 2 segment b 1 segment c. 8 segment d. 3 segment

a. 2 segment cw=4 3-DUP-Ack TH = cw/2 = 2

suppose host A send 3 TCP segments back to back to host B over a TCP connection. the sequence numbers of the 1st, 2nd and 3rd segments are 1000, 1500 and 2500 respectively. how much data is in the 1st segment? a. 500 b. 1000 c. 125 d. 1500

a. 500

suppose the congestion window of a TCP sender was 4 segments long and the threshold is 6 segments. after it receives a new ACK, what would be the new congestion window. a. 8 segments b. 6 segments c. 7 segments d. 5 segments

a. 8 segments cw =4 TH =6 CW <TH //slow start CW = 8

in Tcp which of the following header bits would be set in the response segment sent upon receiving a connection request? a. SYN b. ACK c. FIN d. URG

a. SYN b. ACK

TCP uses which of the following fields in the segment header to determine the socket to pass the received data to? a. destination port number b. source port number c. source IP address d. destination IP address

a. destination port number b. source port number c. source IP address d. destination IP address

why might an application developer choose UDP over TCP? a. no connection establishment b. no congestion control c. more secure d. small header size

a. no connection establishment b. no congestion control d. small header size

suppose the congestion window of a TCP sender is 8 segments and the threshold is 6 segments. after it receives 8 new ACKs, what would be the new congestion window? a. 12 segments b. 14 segments c. 9 segments d. 16 segments

b. 14 segments //cw=8 TH = 6 increase by 1 CW =9

in TCP, which of the following header bits would be set in the connection close request segment? a. SYN b. FIN c. ACK d. URG

b. FIN

in TCP which of the header bits would be set in the connection request segment? a. ACK b. SYN c. URG d. FIN

b. SYN

UDP uses which of the following fields in the segment header to determine the socket to pass the received data to? a. source port number b. destination port number c. source IP address d. destination IP address

b. destination port number d. destination IP address

what functionality does UDP provide beyond what is provided by IP? a. faster communication b. inter process communication c. best effort delivery d. error detection

b. inter process communication d. error detection

in TCP will the loss of an ACK always result in a re-transmission of a segment? a. yes b. no

b. no

if the congestion window of a TCP sender was 4 segments long when a timeout occurred, what would be the new congestion window? a. 8 segments b. 3 segments c. 2 segments d. 1 segments

c. 2 segments

after how many duplicate ACKs does TCP perform a fast re-transmit? a. 2 b. 1 c. 3 d. 4

c. 3

which of the following methods does TCP use for connection establishment? a. 1 way handshake b. 2 way handshake c. 3 way handshake d. 4 way handshake

c. 3 way handshake

what method does TCP use to estimate the round trip time? a. average of 10 precent RTT samples b. most recent sample RTT c. exponential weighted moving average of sample RTT d. four times the recent sample RTT

c. exponential weighted moving average of sample RTT ERTT = 7/8ERTT + 1/8ERTT

which field in the TCP header does a reciver use to infrom the sender about the number of bytes it is willing to accept withput overflowing its buffers? a. send window b. ACK number c. receive window d. congestion window

c. receive window

how does TCP use the estimated round trip time to set the time out interval for transmission of a segment? a. timeout = 4 x estimated RTT b. timeout = estimated RTT c. timeout = estimates RTT + 4 x deviation from estimated RTT d. timeout = 4 x deviation from estimated RTT

c. timeout = estimates RTT + 4 x deviation from estimated RTT

if congestion window of a TCP sender was 4 segments long when a timeout occurred, what would be the new threshold? a. 1 segment b. 8 segment c. 3 segment d. 2 segment

d. 2 segment

what is the size of UDP header? a. 16 bytes b. 12 bytes c. 20 bytes d. 8 bytes

d. 8 bytes