CSSE150(1,2,3) 5stream IITU
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CSSE150(1,2,3) 5stream IITU
Created by CSSE150(1,2,3) 5stream IITU over 6 years ago
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SDP9

Question 1 of 53

1

Layers four and five of the Internet protocol stack are implemented in the end systems but not in the routers in the network core.

Select one of the following:

  • True

  • False

Explanation

Question 2 of 53

1

With ADSL, each subscriber gets more downstream bandwidth than upstream bandwidth.

Select one of the following:

  • True

  • False

Explanation

Question 3 of 53

1

Twisted-pair cooper wire is no longer present in computer networks.

Select one of the following:

  • True

  • False

Explanation

Question 4 of 53

1

4. Two packets A and B are sent in that order through a connection-oriented communication network. They could arrive at the destination:

Select one of the following:

  • a. in any order, after having traversed the same route.

  • b. only in the order A-B, after possibly having traversed different routes.

  • c. in any order, after possibly having traversed different routes.

  • d. only in the order A-B, after having traversed the same route.

Explanation

Question 5 of 53

1

5. Two packets A and B are sent in that order through a connectionless communication network. They will arrive at the destination:

Select one of the following:

  • a. in any order, after possibly having traversed different routes.

  • b. in the order A-B, after having traversed the same route.

  • c. in any order, after having traversed the same route.

  • d. in the order A-B, after possibly having traversed different routes.

Explanation

Question 6 of 53

1

6. The Internet received its name in the 1980s because:

Select one of the following:

  • a. it was an interim (temporary) design of what it later became, but the name stuck.

  • b. it was meant to be a network internal to the United States Department of Defense.

  • c. it consisted of many interconnected networks.

  • d. it achieved international scope with the addition of the City University of London.

Explanation

Question 7 of 53

1

DNS lookups often involve a combination of recursive and iterative queries.

Select one of the following:

  • True

  • False

Explanation

Question 8 of 53

1

The Date: header in the HTTP response message indicates when the object in the response was last modified.

Select one of the following:

  • True

  • False

Explanation

Question 9 of 53

1

Skype relay nodes are typically peers under the control of Skype users.

Select one of the following:

  • True

  • False

Explanation

Question 10 of 53

1

The process that sends messages into, and receives messages from, the network through a software interface is called a socket.

Select one of the following:

  • True

  • False

Explanation

Question 11 of 53

1

In a P2P File Distribution architecture, the server must sequentially send (upload) file copies.

Select one of the following:

  • True

  • False

Explanation

Question 12 of 53

1

12. SMTP is used to:

Select one of the following:

  • a. to transfer messages from one mail server to another.

  • b. to transfer messages from mail server to a user agent.

  • c. to define the format of message headers.

  • d. all of the above.

Explanation

Question 13 of 53

1

13. Suppose a DNS resource record has Type=MX. Then:

Select one of the following:

  • a. Value is the hostname of the DNS server that is authoritative for Name.

  • Value is the IP address of the mail server that has the alias hostname Name.

  • c. Value is the hostname of the mail server that has the alias hostname Name.

  • d. none of the above.

Explanation

Question 14 of 53

1

14. Local DNS name servers:

Select one of the following:

  • a. cache resource records, but discard them after a period of time that is on the order of a few days.

  • b. cache resource records and never discard them.

  • c. obtain resource records from Web caches.

  • d. never cache resource records.

Explanation

Question 15 of 53

1

Consider an HTTP Web server using persistent connections. Suppose the server spawns a
separate process for each client that connects to the server. Then each of these spawned processes will have different server port numbers.

Select one of the following:

  • True

  • False

Explanation

Question 16 of 53

1

The size of the TCP RcvWindow never changes throughout the duration of the connection.

Select one of the following:

  • True

  • False

Explanation

Question 17 of 53

1

17. When a TCP segment arrives to a host, the socket to which the segment is directed depends on

Select one of the following:

  • a. the source IP address of the datagram that encapsulated the segment.

  • b. the destination port number.

  • c. the source port number.

  • d. all of the above.

Explanation

Question 18 of 53

1

18. UDP has which of the following characteristics:

Select one of the following:

  • a. regulated send rate.

  • b. connection state at the server.

  • c. three-way hand shake for connection establishment.

  • d. none of the above.

Explanation

Question 19 of 53

1

19. When a UDP segment arrives to a host, in order to direct the segment to the appropriate socket, the OS uses:

Select one of the following:

  • a. the source port number.

  • b. the source IP address.

  • c. the destination port number.

  • d. all of the above.

Explanation

Question 20 of 53

1

20. Suppose a client sends an HTTP request message with the If-modified-since: header. Suppose the object in a server has not changed since the last time a client retrieved the object. Then the server will send a response message with the status code:

Select one of the following:

  • a. 404 Not Found.

  • b. 200 OK.

  • c. 304 Not Modified.

  • d. none of the above.

Explanation

Question 21 of 53

1

21. Streams are not needed in which of the following programs:

Select one of the following:

  • a. TCPserver.

  • b. UDPserver.

  • c. TCPclient.

  • d. UDPclient.

Explanation

Question 22 of 53

1

22. Consider the minimum time for P2P file distribution, as discussed in Section 2.6. Suppose the upload rate of the server is10 Mbps, the upload rates of all peers is 1 Mbps, and the download rates of all peers is 10 Mbps. Further suppose that there are 100 peers and the file is 100 million bits. The minimum distribution time is

Select one of the following:

  • a. approximately 100 seconds.

  • b. approximately 10 seconds.

  • c. approximately 1 second.

  • d. approximately 1000 seconds.

Explanation

Question 23 of 53

1

For BitTorrent, which of the following is true:

Select one of the following:

  • a. Although a peer may have 50 concurrent TCP connections with other peers, at any given instant of time it sends data to less than 10 other peers.

  • b. At a given instant of time, a peer A may upload to a peer B, even if peer B is not sending anything to A.

  • c. Among the chunks that a peer does not have, the peer will request chunks that appear to be relatively rare in the torrent.

  • d. All of the above.

Explanation

Question 24 of 53

1

24. Consider the latency model for dynamic congestion windows. Which of the following components contribute to latency?

Select one of the following:

  • a. the sum of all the stalled times.

  • b. round trip time, RTT.

  • c. the transmission time of the object, O/R.

  • d. all of the above.

Explanation

Question 25 of 53

1

25. TCP applies fast retransmit to a segment when:

Select one of the following:

  • a. it estimates unusually large RTTs.

  • b. it receives three ACKs for an earlier segment.

  • c. the segment's timer expires.

  • d. none of the above.

Explanation

Question 26 of 53

1

26. Nmap is often used to:

Select one of the following:

  • a. do port scans over a range of ports at a target host.

  • b. measure throughput between hosts.

  • c. measure round-trip times between hosts.

  • d. decipher encrypted traffic.

Explanation

Question 27 of 53

1

27. With SYN cookies, when a server receives a SYN segment, it returns a SYNACK with:

Select one of the following:

  • a. an initial sequence number that is a hash of the IP addresses and port numbers in the SYN segment (as well as of other things).

  • b. initial sequence number 1.

  • c. a randomly chosen initial sequence number.

  • d. none of the above.

Explanation

Question 28 of 53

1

Before sending a packet into a datagram network, the source must determine all of the links that packet will traverse between source and destination.

Select one of the following:

  • True

  • False

Explanation

Question 29 of 53

1

The primary role of a router is to forward datagrams from input links to output links.

Select one of the following:

  • True

  • False

Explanation

Question 30 of 53

1

Forwarding involves transferring a packet from the router’s input link to the appropriate output link.

Select one of the following:

  • True

  • False

Explanation

Question 31 of 53

1

All link layer protocols that support IP have the same frame structure (i.e., length of frame,
number and length of header fields).

Select one of the following:

  • True

  • False

Explanation

Question 32 of 53

1

CRC error detection, as used in Ethernet, is always able to detect whether there is an error in a frame.

Select one of the following:

  • True

  • False

Explanation

Question 33 of 53

1

The even parity bit scheme can correct single bit errors.

Select one of the following:

  • True

  • False

Explanation

Question 34 of 53

1

With CDMA, each sender uses the same code, cm, m=1,...,M.

Select one of the following:

  • True

  • False

Explanation

Question 35 of 53

1

Each LAN adapter has a unique LAN address.

Select one of the following:

  • True

  • False

Explanation

Question 36 of 53

1

41. A channel partitioning protocol has which of the following characteristics forwarding table is:

Select one of the following:

  • a. it does not generate collisions.

  • b. all transmitting nodes get the same amount of bandwidth.

  • there is no master node.

  • d. all of the above.

Explanation

Question 37 of 53

1

42. In slotted ALOHA with N active nodes, the probability that no node transmits in a given slot is

Select one of the following:

  • a. (1-p)N

  • b. (1-p)N

  • c. pN

  • d. 1-p

Explanation

Question 38 of 53

1

43. An ARP query packet is encapsulated in

Select one of the following:

  • a. an IP datagram.

  • a link-layer frame addressed to a specific adapter.

  • a link-layer broadcast frame.

  • none of the above.

Explanation

Question 39 of 53

1

Ethernet provides which of the following services to the network layer

Select one of the following:

  • a. error detection.

  • flow control.

  • reliable data transfer.

  • all of the above.

Explanation

Question 40 of 53

1

45. For Ethernet, if an adapter determines that a frame it has just received is addressed to a different adapter

Select one of the following:

  • a. it discards the frame without sending an error message to the network layer.

  • it discards the frame and sends an error message to the network layer.

  • it sends a NACK (not acknowledged frame) to the sending host.

  • it delivers the frame to the network layer, and lets the network layer decide what to do.

Explanation

Question 41 of 53

1

A typical "infrastructure network" wireless network includes base stations.

Select one of the following:

  • True

  • False

Explanation

Question 42 of 53

1

In CDMA, the chipping rate is typically the same as the original data rate.

Select one of the following:

  • True

  • False

Explanation

Question 43 of 53

1

The 11 channels in the 802.11 are non-overlapping.

Select one of the following:

  • True

  • False

Explanation

Question 44 of 53

1

If you enter an Internet café and more than one AP is present, then the packets your host

Select one of the following:

  • True

  • False

Explanation

Question 45 of 53

1

During the 802.11 association handshake protocol, the wireless host gets assigned an IP address.

Select one of the following:

  • True

  • False

Explanation

Question 46 of 53

1

51. In CDMA, let Ym be the received value in the mth mini-slot for some slot i. Let cm, m=1,...,M, be the sender's M code values. To determine the bit value the sender sent, the receiver:

Select one of the following:

  • a. multiples Ym with the sum of the M code values.

  • b. multiplies each Ym with the corresponding cm, sums the resulting values and divides by M.

  • simply declares Ym as the sent value.

  • d. none of the above.

Explanation

Question 47 of 53

1

52. A beacon frame sent by an AP includes

Select one of the following:

  • a. the AP's SSID.

  • b. the AP's MAC address.

  • c. both the AP's MAC address and SSID.

  • d. none of the above.

Explanation

Question 48 of 53

1

53. The 802.11 protocol does not implement collision detection because (Click all that apply)

Select one of the following:

  • a. collision detection was found to be useless in wired Ethernet.

  • b. the adapter would still not be able to detect all collisions due to hidden terminals.
    c. it is costly to build wireless hardware that detects collisions.

  • c. it is costly to build wireless hardware that detects collisions.

  • d. all of the above.

Explanation

Question 49 of 53

1

54. Packets sent by two stations in 802.11 can collide because

Select one of the following:

  • a. at a given time, the random backoff values of the two stations are the same.

  • b. the packets are sent to different APs but on the same channel.

  • c. the two stations could be hidden from each other.

  • d. all of the above.

Explanation

Question 50 of 53

1

An 802.11 frame includes:

Select one of the following:

  • a. an acknowledgement field.

  • b. a sequence number field.

  • c. four address fields.

  • d. all of the above.

Explanation

Question 51 of 53

1

In IP spoofing, the attacker interchanges the source and destination addresses in the sender's IP datagram.

Select one of the following:

  • True
  • False

Explanation

Question 52 of 53

1

Nonce's are often used to combat the playback attack.

Select one of the following:

  • True

  • False

Explanation

Question 53 of 53

1

65. Filtering in a firewall can be based on:

Select one of the following:

  • a. source and destination IP addresses

  • b. TCP ACK bits

  • c. source and destination port numbers

  • d. all of the above

Explanation

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