Networking Test I -- The Xena and Gabi Test

  1. (Yes/Yes) Did you put your name on the test?
  2. (3 points) What is the current latency and bandwidth between here and www.xena.com?  You get one point for measuring the right data, one point for writing down the right equations, and one point for the right solution to them.  Don't forget to put units of measure.  (i.e.  don't say that the latency is 28, say its 28 bytes or seconds or gallons).

    3. Data: __________________________________________________________________________
    Equations: ______________________________________________________________________
    Latency: ________________________________________________________________________
    Bandwidth: ______________________________________________________________________
  3. The maximum packet size on our ethernet is 1500 bytes.  Yet you can ping a 4000 bytes message to www.xena..com (feel free to try it).  How does such a large message get from here to there?
    __________________________________________________________________________________________________
    __________________________________________________________________________________________________
    __________________________________________________________________________________________________
  4. Suppose a host has two network adapters, one token ring and one ethernet.  The day is Tuesday.  Both networks are part of the internet.  The computer is a Mac.  How many IP numbers does the computer have?

    5. _____________________________________________________
  5. What class address is IP address 134.10.16.102?
    1. Class A
    2. Class B
    3. Class C
    4. Class D
    5. Class E
    6. Xena has class.
  6. (Yes/No) If I switch ethernet cards on a computer, does the IP number necessarily change?
  7. (Yes/No)Does Ethernet use Frequency Division Multiplexing?
  8. Suppose I have a very lightly loaded network.  My one goal is to minimize the average latency of small messages.  Which is the best type of network.  Why
    1. 10 megabits/sec Ethernet.  Why: _______________________________________________
    2. 10 megabits/sec Token Ring.  Why: _____________________________________________
  9. (Two points) I notice that as more and more clients on my ethernet become busy, total network traffic successfully passed from all senders to all receivers drops, even though my clients have lots of data to transmit.

    10. Why?________________________________________________________________________________
    _____________________________________________________________________________________
    How can I fix it? _______________________________________________________________________
    ____________________________________________________________________________________
  10. Suppose I want to translate the name xena.and.gabi.com to an IP number.  What is the most number of packets (queries) I might have to generate and what is each query?

    11. 1) __________________________________________________________________
    2) __________________________________________________________________
    3) __________________________________________________________________
    4) __________________________________________________________________
    5) __________________________________________________________________
    Others) ______________________________________________________________
  11. What layer is Token Ring (circle all that apply)
    1. Physical
    2. Data Link
    3. Network
    4. None
  12. Which statement is most true of slotted Aloha?
    1. Xena could kick Gabi's butt.
    2. Gabi cooks fish better than Xena.
    3. Apollo and Xena should just move on.
    4. Xena's really Hercules's sister.
  13. What is the maximum latency before a node can access the ethernet?

    14.          1.Twice the propogation delay across the cable.
             2.Twice the propgation delay accross the cable plus the length of time needed to transmit a maximum size packet.
             3.Infinite
             4.28 ms.
  14. Which system call can take the longest amount of time?
    1. gethostbyname()
    2. bind()
    3. accept()
    4. socket()
  15. The function gethostbyname returns a pointer to a structure.  What does it return on error?
    _____________________________________________________________________________________________
  16. List two things that can cause an error in gethostbyname().
    _____________________________________________________________________________________________
    _____________________________________________________________________________________________
  17. (Two Points) Suppose I change the ethernet backoff algorithm.  Recall that after a collision normal ethernet chooses an interval, and then picks a random number within the interval, and finally waits the chosen amount of time before retransmitting.  Instead, I propose to to always pick a random number in the range 10 .. 20 milliseconds.  Considering both reliability and performance, compared to normal ethernet ...
    How will this work in a small, lightly loaded network?___________________________________________________
    _____________________________________________________________________________________________
    How will this work in a large, very heavily loaded network. ______________________________________________
    ______________________________________________________________________________________________
  18. I want to redesign ethernet.  Suppose I want to increase the maximum distance between two ethernet nodes.  What can I do?
    1. Decrease the maximum packet size
    2. Increase the maximum packet size
    3. Decrease the minimum packet size
    4. Increase the minimum packet size
    5. Paket size has nothing to do with the ethernet distance limitation
  19. What does the bind() system call do?

    20.          1.Gives an otherwise anonymous socket an address.
             2.Tells the operating system how large the backlog of requests can be.
             3.Changes the socket to send datagrams instead of streams.
             4.Creates a file descriptor and connects that descriptor to a socket.
             5.All or none of the above.
  20. What does the accept() system call do?

    21.          1.Gives an otherwise anonymous socket an address.
             2.Tells the operating system how large the backlog of requests can be.
             3.Changes the socket to send datagrams instead of streams.
             4.Creates a file descriptor and connects that descriptor to a socket.
             5.All or none of the above.