Computer Science 881
                            Quiz 5             Name_______________________

1. The occurence of multiple fib_nodes in an hash chain

   a. Will occur whenever a routing    b. Will occur whenever a routing
      table has multiple entries          table has multiple entries
                                          with the same prefix length

   c. May  occur whenever a routing    d. May  occur only if a routing
      table has multiple entries          table has multiple entries with
      with the same prefix length         the same destination address.

2. A single entry in the Linux routing table best corresponds to

   a. An element of type              b. An element of type struct
      struct rtable                      dstentry

   c. An element of type              d. An element of type struct
      struct fib_node                    fibinfo

3. When a routing table lookup occurs for an output route

   a. Both tables will always be      a. Both tables will always be
      searched but a result found        searched but a result found
      in the local table has             in the main table has
      precendence.                       precendence.

   c. The main table will be searched d. The local table will be searched
      first and only if a route is       first and only if a route is
      not found will the local table     not found will the main table
      be searched.                       be searched.

4. For a fib_node to be used for an output route it is necessary that

   a. fn_scope < key->scope           b. fn_scope > key->scope

   c. fn_scope <= key->scope          d. fn_scope >= key->scope

5. Answer the following questions pertaining to fib_select_default()
   and fib_detect_death() T or F.

   ___ a. For a given call to  fib_select_default() the value of
          last_resort will be set at most one time.

   ___ b. For a given call to  fib_select_default() the value of
          last_resort will be set at least one time.

   ___ c. For a given call to  fib_select_default(), fib_detect_death()
          will always be called at least one time.

   ___ d. On the first iteration of the loop in fib_select default
          if next_fi != res->fi, next_fi will be used to route the
          packet instead of res->fi.

   ___ e. The last_resort route will not be used if any fib_node
          on the chain that is searched has an associated fib_info
          for which the neighbour structure associated with the
          fib_info's nh_gw is in the reachable state.




5. How is the source address to be associated with a new output route
   determined in each of the following three cases:

   a. key.src == 0 &&
      key.oif != 0






   b. key.src == 0 &&
      key.oif != 0






   c. key.src != 0 &&
      key.oif != 0






6. When the new route cache element is created, its the src, dst, and
   oif of the key that must be matched in future route cache lookups
   will be set to:

   a. The values originally passed      b. The values contained in the
      to ip_route_output()                 "new" key structure created in
                                            ip_route_output_slow()

   c. The values actually used as       d. a. b. and c. are always
      src, dst, and oif when sending       indentical so they are all true.
      the packet.


7. For  ip_route_input_slow() answer T/F depending upon whether the
   following would be classified as a "martian" <destination>:

   ___ a. The loopback address 127.0.0.1


   ___ b. 140.150.2.11  (assuming no default route nor matching, network
                         or host routing table entry, but that forwarding
                         on the input interface is supported)


8. Precisely how does  ip_route_input_slow() distinguish incoming unicast
   packets that are to be delivered on <this> host from those that
   that should be forwarded on to another host.