Computer Science 825
                         Quiz 1              Name _______________________


1. a. Which of the seven layers of the ISO model is the LOWEST
      layer having end to end responsibilites.



   b. Which of the seven layers of the ISO model would typically
      be responsible for code translation (e.g. EBCDIC <-> ASCII).



   c. Which of the seven layers of the ISO model is the HIGHEST
      layer that resides in the communcations subnet.



   d. Which of the seven layers of the ISO model is responsible
      for checkpointing and recovery from network failures.



2. PROTOCOLs define 3 aspects of messages passed in a network.
   One is the SYNTAX. What are the other two?

   a.

   b.


3. Do protocols (as the term is normally used in networking, e.g
   in SDLC, TCP, or IP) define the rules under which a layer communicates

   a. With the layer above it   b. With a peer layer in another node.

   b. With the layer below it.  d. All of the above.

4. Match the service classes with the appropriate applications
   (No answer should be used more than once.)

   ___ a. File transfer      1. Unreliable Conn Less datagram

   ___ b. Digitized Voice    2. Reliable Conn Less Request/reply

   ___ c. E-Mail             3. Reliable Conn oriented byte stream

   ___ d. Remote login       4. Unreliable Conn oriented byte stream

   ___ e. Database queries   5. Reliable Conn Less datagram

                             6. Reliable Conn oriented message stream

                             7. Unreliable Conn oriented message stream

5. Protocol headers used by a layer N are handled by layer K (K < N)
   as follows:

   a. The are removed before  b. They are treated as user data.
      the packet arrives at
      Layer K

   c. They are deleted by layer K.
---------------------  More on the back ----------------

6. At each layer of the ISO model existing network architectures
   (ISO_OSI, SNA, ARPANET) define:

   a. Exactly one protocol           b. Zero or more protocols.

7. For two separate implementations of a specific network
   architecture to interoperate correctly it is necessary that:

   a. Internal interlevel interfaces  b. Intra level peer protocols
      be comptatible.                    be compatible

   c. Both a and b.