20. The packets on the backlog queue are processed by tcp_v4_do_rcv().

    a. When the backlog queue         b. Whenever the prequeue
       gets too long.                    is too full.

    c. When a periodic timer expires  d. Whenever the sock lock is
                                         released.

21. For each of the following TCP receive queues indicate whether a
    packet might be reside on the queue before (B) or after (A) being
    processed by tcp_v4_do_rcv();

    ___ a. prequeue


    ___ b. receive queue


    ___ c. out-of-order queue


    ___ d. backlog queue


22. Suppose all of the queues contain data. Order them (1, 2, 3, 4)
    by sequence number where 1 means the queue contains the smallest
    sequence number and 4 the larges.

    ___ a. prequeue


    ___ b. receive queue


    ___ c. out-of-order queue


    ___ d. backlog queue