check my answers for Networking I came up with these answers, can check my answe

Question

check my answers for Networking

I came up with these answers, can check my answers

my answers in bold

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Question 5: TCP and Flow Control
You set up an experiment in which host A blasts a 26 Megabyte file to host B through a single TCP Tahoe connection over a 1 Gigabit/sec Ethernet. B transmits no data. Neither host uses any IP or TCP options. The maximum Ethernet payload size is 1500 bytes. With no options, the IP+TCP headers occupy exactly 40 bytes. This leaves a TCP maximum segment size (MSS) of 1,460 bytes, approximately 1/18,000 the size of the file. Which of the following statements are true (check all that apply):

-Host B can send TCP acknowledgements to host A, even though it has no data to send.
-The size of the flow control window in segments B sends (the window field) cannot increase throughout the duration of the connection.
-Suppose that the last RTT sample at host A is 10 msec. The current value of the RTT estimate must be greater than or equal to 10 msec.
-If the user temporarily stops or suspends the process receiving the data on host B, host A will eventually stop sending new data until B's receiver process is resumed.

Question 9
Now let’s compare our answer above with an estimate of the future capacity needed to carry web traffic. We’ll assume 100 million people download an average of 100 web pages per day (i.e. averaged over 24 hours), each containing 1Mbyte of data. If the peak traffic is five times the average, then which of the following is the closest estimate of the capacity needed by the network to deliver this traffic?
-500 Gb/s
-1 Tb/s
-5 Tb/s
-10 Tb/s

Question 10
We can think of the network as a spanning tree, with the video server at the root, and the one hundred million subscribers at the leaves. Assuming that the tree has degree eight (i.e. each router in the tree connects to eight other routers closer to the leaves), then roughly how many routers does a packet pass through from the root to each subscriber?
-9
-10
-11
-12
-13

Question 11: Queues
At the start of every second, a train of 100 bits arrive to a queue at rate 1000 bits/second. The departure rate from the queue is 500 bits/second. The queue is served bit-by-bit, and you can assume the buffer size is infinite.

a) What is the average queue occupancy? (in bits)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
5

b) What is the average delay of a bit in the queue? (in milliseconds)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
0.5

c) If the trains of 100 bits arrived at random intervals, one train per second on average, would the average queue occupancy be the same, lower or higher than in part (a)?
-Higher
-Same
-Lower

d) If the departing bits from the queue are fed into a second, identical queue with the same departure rate, what is the average occupancy of the second queue? (in bits)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
-0

Question 12: Protocol Stack
You plug a new laptop into a wired Ethernet jack for the first time. You have already told the network administrators your MAC address, and can join the network with no further action on your part.

Assume that:
1. your DHCP server is 171.64.7.77,
2. your Ethernet address is 00:11:22:33:44:55
3. the IP address you'll be given is 171.64.7.22
4. the gateway IP address is 171.64.7.1
5. the gateway Ethernet address is 00:66:77:88:99:00
6. the netmask is 255.255.255.0
Let's consider the series of packet exchanges that will occur on the link for your laptop to send a single IP packet to 128.30.2.1. We assume that no packets are lost or discarded, and that no other packets are exchanged on the link.

a) Which of the following protocols are involved in the series of packet exchanges (check all that apply)?
-IP
-ARP
-UDP
-ICMP
-DHCP

b) How many packets will traverse the link ?
-4

c) In which packet (sent or received) will your IP address be mentioned for the first time?
-the 1st packet
-the 2nd packet
-the 3rd packet
-the 4th packet
-the 5th packet

d) How many packets (sent or received) contain the Ethernet address of the gateway?
2

e) How many packets (sent or received) contain the IP address of the DHCP server?
10

Explanation / Answer

Question 10
We can think of the network as a spanning tree, with the video server at the root, and the one hundred million subscribers at the leaves. Assuming that the tree has degree eight (i.e. each router in the tree connects to eight other routers closer to the leaves), then roughly how many routers does a packet pass through from the root to each subscriber?
Answer: 10

Question 11: Queues
At the start of every second, a train of 100 bits arrive to a queue at rate 1000 bits/second. The departure rate from the queue is 500 bits/second. The queue is served bit-by-bit, and you can assume the buffer size is infinite.

a) What is the average queue occupancy? (in bits)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
Answer: 5 bits

b) What is the average delay of a bit in the queue? (in milliseconds)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
Answer: 0.05s

c) If the trains of 100 bits arrived at random intervals, one train per second on average, would the average queue occupancy be the same, lower or higher than in part (a)?
Answer: Higher

d) If the departing bits from the queue are fed into a second, identical queue with the same departure rate, what is the average occupancy of the second queue? (in bits)
Note: Enter an integer. Any other kind of answer will result in a 0 point grade for this question.
Answer: 0.2 bits

Question 12:

a) Which of the following protocols are involved in the series of packet exchanges (check all that apply)?

Answer: IP, ARP, UDP, DHCP

b) How many packets will traverse the link ?

Answer: 3

c) In which packet (sent or received) will your IP address be mentioned for the first time?

Answer: 4th packet => 171.64.7.1

d) How many packets (sent or received) contain the Ethernet address of the gateway?

Answer: 2

e) How many packets (sent or received) contain the IP address of the DHCP server?
Answer: 1

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