Computer Science 881
                             Quiz 2           Name____________________

1. ICMP packets are

   a. Encapsulated in IP              b. Sent standalone without
      datagrams.                         even an ethernet header

   c. Have an ethernet header         d. Sent as a UDP packet.
      but no IP header.

2. The standard "ping" program:

   a. Sends a UDP packet and            b. Sends an ICMP packet and
      receives an ICMP reply.              receives a UDP reply

   c. Sends a UDP packet and            d. Sends an ICMP packet and
      receives a UDP reply                 receives an ICMP reply

3. When a "ping" packet travels across the network

   a. An ICMP echo reply is returned    b. An ICMP echo reply is returned
      by every router through which        only by the destination host.
      it passes.

   c. no ICMP echo replies are generated
      at all because ping uses UDP.

4. The reason that the "ping" program must be run with root privileges
   is that:

   a. The getprotobyname() function     b. Creation of a socket of
      fails since ICMP is a protected      type SOCK_RAW fails on Unix
      protocol.                            systems unless the caller is
                                           running as root.

   c. The gethostbyname() function      d. All of the above
      is priviledged.

5. ICMP query replies are delivered to:

   a. Only to the sender of the       b. Any process whose PID
      query request.                     matches the "id" field in
                                         header.

   c. All processes who have an       d. All processes in the system.
      ICMP socket open.

6. ICMP error messages are delivered to:

   a. Only to the sender of the       b. Any process whose PID
      packet that caused the problem     matches the "id" field in
                                         header.

   c. All processes who have an       d. All processes in the system.
      ICMP socket open.

7. Identify two of the five classes of messages for which
   ICMP error messages MUST NOT be generated:


   1 -


   2 -


8. Identify the elements comprising an ICMP error message:















9. Suppose the method proposed in class for guesstimating bandwidth
   and delay is being used and the following measures are captured:

                                 Time to H1          Time to H2

   Small packet (125 bytes)        10 msec            20 msec


   Big packet  (1000 bytes)        20 msec            40 msec


   a. Find the H1-H2  bandwidth in Kbits / sec (Here K is 1000 not 1024)











   b. Find the H1-H2 latency in msec