Computer Science 853
                               Quiz 8        Name _________________

1. The occurence of multiple fib_nodes in a single 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. 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.

3. During a FIB table lookup

   a. Only one fn_zone will           b. It may be necessary to search
      ever need be be searched           several zones or one may
                                         suffice
   c. All zones must always be
      searched

4. The IP address of the next hop of a route is kept in which
   of the following structures:

   a. fib_nh                          b. fib_node

   c. fn_zone

5. The IP address that is compared with the input key in the FIB lookup
   process is kept in which   of the following structures:

   a. fib_nh                          b. fib_node

   c. fn_zone                         d. fib_info

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

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

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


7. 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

8. Answer the following questions pertaining to fib_select_default()
   and fib_detect_death() T or F. (Assume there are exactly three
   default routes and that they all have different fib_info's and
   different next hop gateways).

   ___ 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. It is possible for an unreachable gateway to be used


9. 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.


10. In a FIB lookup the zone associated with a "default" route will be
    searched:

    a. first, because most requests       b. last because it corresponds
       use the default route                 to a 0 length prefix.

    c. in random order based on a
       hash function.

11. Suppose source address, destination address, and oif are
    specified and that the source address is a legit unicast address
    on this machine and that the dest address is a legit unicast
    address elsewhere in the Internet. Which of the following
    conditions will cause a possible output route to be rejected

    a. source address is on an interface   b. only route to next hop doesn't
       other than oif                         use oif

    c. both of the above                   d. neither of the above


12. Assuming the destination address of an incoming packet is a
    unicast owned by this host and that the incoming interface has
    an IP address and rpf is disabled on that interface what if any
    characteristics of the source address will cause the packet to
    be dropped.