Computer Science 853
                            Quiz 7             Name_______________________


(For all questions referring to ARP states you should EXCLUDE
NUD_NOARP and NUD_PERMANENT from consideration and from your answer)

Suppose host 192.168.2.15 is on the same LAN with me but that it
hasn't been contacted since my host was last booted.  If I now send
a UDP packet to 192.168.2.15...

1. A new neighbour structure will be created

   a. at the time the route cache     b. At the time the packet is being
      element is created via call        transmitted by ip_finish_output2()
      to ip_route_output_slow()

   c. Since we are on the same LAN
      no new neighbour structure
      is required.

2. and the sending of the ARP request packet will occur

   a. at the time the route is        b. At the time the packet is being
      resolved during the call to        transmitted by ip_finish_output2()
      ip_route_output_slow()

   c. Since we are on the same LAN
      no ARP request
      is required.

3. In the above scenario, at entry to ip_finish_output2()

   a. neighbour structure for         b. It will exist an be in the
      192.168.2.15 won't yet exist       NUD_CONNECTED state

   c. It will be in the               d. It will be in the NUD_NONE
      NUD_INCOMPLETE state               state

4. When 192.168.2.15 receives my ARP request

   a. it will create a neighbour      b. it will create a neighbour
      struct and set its state to        struct and set its state to
      NUD_STALE                          NUD_REACHABLE


   c. It won't create a neighbour
      structure until an application
      tries to respond to me.


5. Neighbour and route cache structures are related transient data structures.
   Suppose a related pair are haven't been used in some time and need to
   be destroyed.  Which one must be destroyed first?

   a. the struct rtable               b. the struct neighbour

   c. whichever one's expiry
      timer fires first


6. In which of the SIMPLE STATES <<at entry>> to  neigh_event_send()
   will an ARP request actually be sent.  ( NUD_IN_TIMER, NUD_CONNECTED,
   NUD_VALID are NOT simple states)







7. In which of the SIMPLE STATES <<at entry>> to neigh_resolve_output()
   will neigh_resolve_output() invoke dev_queue_xmit() before returning.






8. Precisely what causes each of the following transitions.  If the transition
   is triggered by a timer indiciate WHICH timer. If the transition
   is triggered by an attempt to send or the arrival of a packet say so.
   If the transition can't happen,  say so.

   a. REACHABLE to STALE





   b. STALE to DELAY





   c. STALE to DEAD





   d. DELAY to PROBE




9. In what states is receipt of an ARP <<response>> an expected event.








10. What will happen if a SPOOFED are response is received in the
    NUD_REACHABLE state?