Computer  Science 826
                        Quiz 3  -         Name ________________________

1. The ARP pathology example in the book shows that a UDP datagram
   transmission from a host on an ethernet will fail:

   a. Any time the packet to be sent   b. Whenever the next hop hardware
      is larger than Ethernets MTU        address is not in the ARP cache.

   c. Either a. or b. is true.         d. both a. and b. are true.

2. 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.

3. 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

4. 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.

5. 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.

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. The "original" traceroute program:

    a. Sends ICMP and receives ICMP      b. Sends UDP and receives UDP

    c. Sends ICMP and receives UDP       d. Sends UDP and receives ICMP



8. The socket used for sending in the original traceroute is
   created using:

   a. socket(AF_INET, SOCK_DGRAM, 0);    b. socket(AF_INET, SOCK_RAW, 1);

   c. socket(AF_INET, SOCK_RAW, IPPROTO_RAW))


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 (250 bytes)        10 msec            20 msec


   Big packet  (1250 bytes)        20 msec            50 msec


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











10. Assuming "traceroute" is working correctly, how many messages
    should be received by the host initiating the traceroute for
    each packet that it transmits.

    a. 1                               b. One for each router the
                                          transmission passes through.

    c. None (unless the transmission
       succeeds in arriving at the
       destination named in the IP
       header.).

11. In the new and improved traceroute of RFC 1393, how many messages
    should be received by the host initiating the traceroute for each packet
    that it transmits.

    a. 1                               b. One for each router the
                                          transmission passes through.
    c. None (unless the transmission
       succeeds in arriving at the
       destination named in the IP
       header.).