Host A sends the information of size 3000 bytes to Host B using TCP protocol. As long as Host B receives each packet in size 1000 bytes, Host B must acknowledge Host A. We assume the header size in...

Host A sends the information of size 3000 bytes to Host B using TCP protocol. As long as Host B receives each packet in size 1000 bytes, Host B must acknowledge Host A. We assume the header size in each packet is 40 bytes, the starting sequence number used by Host A is 1000, and the window size of the sender side is 3000 bytes. What is the value of SND.NXT when the first packet is sent out, but not acknowledged?

1000

2000

3000

1999

If a host is monitored, and there are seven TCP packets captured: {S1, S2, S3, S4, S5, S6, E1}, where Si represents ith Send packet, and Ej represent jth Echo packet. E1 here acknowledges and echoes all the six Send packets cumulatively. Which of the follow matching can make more sense to represent the RTT of the connection chain?

E1 matches with S1

E1 matches with S4

E1 matches with S5

E1 matches with S6