Networking Final (Concrete Blonde Version)

1. How long does it take to transmit a packet (assume no failures).  You may use the variables 'latency', 'bandwidth', and 'packet_size'.

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2. What is availability?
1. The rate at which the network can accept data.
2. The amount of time the network is working properly.
3. The rate at which packets accepted by the network are delivered to their destinations.
4. Love is the beast, eating your heart.  Love is the vampire, drunk on your blood.
3. (Yes/No) Is Ethernet a half-duplex link?
4. When is selective repeat particularly better than alternating bit and go back N?
1. With small packet sizes and low latencies and high error rates.
2. With small packet sizes and high latencies and high error rates.
3. With large packet sizes and low latencies and low error rates.
4. With large packet sizes and high latencies and low error rates.
5. Suppose I send a box holding 100 data tapes at 2 gigaBYTES each.  How many DAYS would a T1 line (1.54 megaBITS/second) to transmit the same data.  Show work for partial credit. _____________________________________________________________________________
6. Which is a good use of datagrams?
1. Continus streaming very high data rate video transmissions.
2. Bank transactions such as check clearing or ATM machines.
3. Industrial control applications such as atomic power plant monitoring.
4. Got a bottle of Tequila, who needs friends.  I know a hundred games of solitaire.
7. Which OSI network layer describes how long a voltage must be placed upon an ethernet wire to represent a single bit?
1. Physical
2. Data Link
3. Network
4. Application
5. They could talk talk talk forever ... they probably will.
8. Which OSI network layer manipulates the most bytes?
1. Physical
2. Data Link
3. Network
4. Application
9. Which OSI network layer describes how long an unacknowledged Ethernet packet can go before a retransmission is sent?
1. Physical
2. Data Link
3. Network
4. Application
10. Consider the function call gethotsbyname().  Which system does gethostbyname() access.
1. NFS (Network file system).
2. ARP (Address resolution protocol).
3. DNS (Domain name system).
4. None or all of the above.
11. How many possible internet addresses are there?  Ignore the multicast addresses, just use the normal single-host addresses.  Show work of partial credit.  Hint:  It's not 2^32 nor 2^31.
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12. (Y/N) The telnet port is port 23.  Does this mean that the data representing my keystrokes are sent over port 23.  Assume I'm actually using telnet as intended.
13. Which are advantages of Ethernet like protocols (put an E) and which are advantages of Token Ring like protocols (put a T) or equal (put an EQ)?

Known delays

Small latencies for lightly loaded network

High efficiency for heavily loaded network

Easier and simpler to implement

Can be used by TCP/IP

Can be used to transmit http data

14. (Y/N) Consider virtual circuits and virtual circuit type routing.  Can packets arrive in a different order than they are sent?
15. List two factors that should be used as a weighting or cost function for Dijkstra spanning tree algorithm when used for routing decisions.
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16. _______ Using HTTP/0.9 (the old one), how many data items can be requested over a single connection?
17. _______ Consider Netscape (a web client) and Apache (a web server).  Both are written in C for UNIX.  Which of them MUST have a listen() system call?
18. Please name one file system operation besides delete that cannot be made idempotent
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19. Which type of attack on a crypt system is the strongest (provides the most data to the decryption effort).
1. Cyphertext only attack
2. Chosen plaintext attack
3. Known plaintext attack
4. He was the ghost of a Texas Lady's Man.
20. (2 pts) Which operations should I do to send secret data to Jeff using public key crypt, and what does he do to read it.  You may assume that we both know everybody's public key, and that we each know our own private key.
    Me:_____________________________       Jeff:_______________________________________
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21. Suppose I want to sign something electronically, and give to Jeff.  Which key should I use?
1. My private key
2. My public key
3. Jeff's private key
4. Jeff's public key.

22. What is the best route and cost from A to I? _______________________________________
23. What is the best route and cost from O to B?________________________________________
24. (Talker question) Why does ethernet use an adaptive random delay for retransmissions?  Why not just use a random delay with a fixed distribution, for instance a linear distribution between 10 and 100 ms.
25. (Talker Question) Consider an enviornment that has very high latency and high bandwidth.  Which would transmit data faster, a series of http requests in parallel or a series of http requests one after the other?  Why?