export_final (1)

Question 1

TCP implements network fairness directly.

Answer 1

false

Question 2

TCP has a congestion control mechanism.

Answer 2

true

Question 3

TCP implements network fairness indirectly.

Answer 3

true

Question 4

What are some possible consequences of network-core congestion? (Check all that apply)

Answer 4

Delayed packets Network collapse Dropped Packets Out-of-order packet arrival Increased network congestion

Question 5

Given a 4 Gbps link with TCP applications A, B, and C. Application A has 29 TCP connections to a remote web server Application B has 2 TCP connection to a mail server Application C has 14 TCP connections to a remote web server. According to TCP “fairness”, during times when all connections are transmitting, how much bandwidth should Application C have? (Give answer in Mbps, rounded to one decimal place, without units. So for an answer of 1234,567,890 bps you would enter “1234.6” without the quotes.)

Answer 5

1244.4

Question 6

For the following binary IP address, give the dotted-decimal representation: 11000000 10101000 00001011 00010100

Answer 6

192.168.11.20

Question 7

For the following dotted-decimal IP address, give the binary representation: 10.108.112.240

Answer 7

00001010 01101100 01110000 11110000

Question 8

For the following binary IP address, give the dotted-decimal representation: 10011000 11101110 10011101 11000011

Answer 8

152.238.157.195

Question 9

A network with a connectionless network layer is called a datagram network .

Answer 9

datagram network

Question 10

In a subnet, the reserved addresses are the __________ (with a lowest subnet IP address) and the ____________ (with a highest subnet IP address).

Answer 10

subnet address, broadcast address

Question 11

When a host in a network needs to obtain a valid IP address for itself, it broadcasts a “discover” message that can be handled by a Dynamic Host Configuration Protocol (DHCP) server, which will “offer” an IP address within the correct domain.

Answer 11

Dynamic Host Configuration Protocol (DHCP)

Question 12

The Internet Protocol (IP) implements flow control.

Answer 12

false

Question 13

The process of moving a datagram from a router’s input port to output port is handled by the switching fabric .

Answer 13

switching fabric

Question 14

In addition to a “default” entry, routing tables in an internet store…

Answer 14

the “first hop” in a path to each of the networks known to the router

Question 15

In a datagram network, the responsibilities of the network layer include: (check all that apply).

Answer 15

host-to-host communication packet forwarding packet routing

Question 16

Given a router with 5 input ports and 5 output ports. If the switching fabric is 5 times as fast as the input/output line speed, queueing can occur at an output port.

Answer 16

can

Question 17

Where do network-layer protocols run?

Answer 17

PCs Mobile devices Laptops Routers

Question 18

The Internet Protocol (IP) header may be 28 bytes long.

Answer 18

true

Question 19

What can cause packet queueing at a router’s output port?

Answer 19

Multiple data flows requiring the same outbound link. Slow outbound link transmission rate.

Question 20

The Internet Protocol (IP) implements data reliability services

Answer 20

false

Question 21

The network layer manages communications from host to host .

Answer 21

host to host

Question 22

The Internet Protocol (IP) header may be 21 bytes long.

Answer 22

false

Question 23

For the IPv4 CIDR address 153.10.22.56 /22 What is the… Netmask: Network Address: Host Mask: 0.0.3.255 Broadcast Address: Number of possible hosts: 1022 Host Number:

Answer 23

Answer 1: Correct! 255.255.252.0 Answer 2: Correct! 153.10.20.0 Answer 3: Correct! 0.0.3.255 Answer 4: Correct! 153.10.23.255 Answer 5: Correct! 1022 Answer 6: Correct! 568

Question 24

What are some causes of network congestion? (Check all that apply)

Answer 24

Typical Internet Usage. Correct! Parallel TCP Connections. Correct! High utilization. Correct! Dropped TCP Packets. Correct! Reliable Data Transfer schemes.

Question 25

A host starts a TCP transmission with an EstimatedRTT of 10.2ms (from the “handshake”). The host then sends 3 packets and records the RTT for each: SampleRTT1 = 39.7 ms SampleRTT2 = 37.8 ms SampleRTT3 = 19.4 ms (NOTE: SampleRTT1 is the “oldest”; SampleRTT3 is the most recent.) Using an exponential weighted moving average with a weight of 0.4 given to the most recent sample, what is the EstimatedRTT for packet #4? Give answer in miliseconds, rounded to one decimal place, without units, so for an answer of 0.01146 seconds, you would enter "11.5" without the quotes.

Answer 25

24.8

Question 26

For the following binary IP address, give the dotted-decimal representation: 11011110 01110011 01100110 01100110

Answer 26

222.115.102.102

Question 27

In a datagram network, the responsibilities of the network layer include: (check all that apply).

Answer 27

Correct Answer host-to-host communication Correct Answer packet routing Correct Answer packet forwarding

Question 28

In host-inferred congestion control, congestion is detected based on delayed and/or dropped packets.

Answer 28

host inferred

Question 29

UDP uses an additive-increase multiplicative-decrease (AIMD) system to manage flows.

Answer 29

false

Question 30

Select the appropriate new CongWin sizes for the following TCP Reno congestion scenario. Assume ssthresh is initially set to 8 MSS: Connection Established with new server host. CongWin = ACK(s) received from first segment set. CongWin = ACK(s) received from next segment set. CongWin = 2 MSS ACK(s) received from next segment set. CongWin = ACK(s) received from next segment set. CongWin = ACK(s) received from next segment set. CongWin = Triple Duplicate ACK occurs. CongWin = , ssthresh = 4 MSS ACK(s) received from next segment set. CongWin =

Answer 30

Connection Established with new server host. CongWin = 1MSS ACK(s) received from first segment set. CongWin = 2MSS ACK(s) received from next segment set. CongWin = 4 MSS ACK(s) received from next segment set. CongWin = 8MSS ACK(s) received from next segment set. CongWin = 9MSS ACK(s) received from next segment set. CongWin = 10MSS Triple Duplicate ACK occurs. CongWin = 8MSS , ssthresh = 5 MSS ACK(s) received from next segment set. CongWin = 9MSS

Question 31

Given a nodal delay of 64.7ms when there is no traffic on the network (i.e. usage = 0%), what is the effective delay when network usage = 94.6% ? (Give answer is miliseconds, rounded to one decimal place, without units. So for an answer of 0.10423 seconds you would enter "104.2" without the quotes). You Answered

Answer 31

1198.1

Question 32

Which of the following are benefits of a virtual circuit network? (Check all that apply)

Answer 32

Correct! Guaranteed timing. Correct! Guaranteed bandwidth. Correct! Connection states are preserved.

Question 33

Which of the following are benefits of a datagram network? (Check all that apply)

Answer 33

Faster delivery. Less overhead than a VC network.

Question 34

A network with a connection-oriented network layer is called a

Answer 34

virtual circuit network

Question 35

The path MTU is the smallest MTU on a path from sender to receiver

Answer 35

true

Question 36

The "ping" application (on Windows) uses ICMP echo request/reply.

Answer 36

true

Question 37

Network address translation is strictly a Layer-3 protocol.

Answer 37

false

Question 38

ICMP messages are carried within the payload of IP datagrams.

Answer 38

true

Question 39

It is the responsibility of a routing algorithm to correlate MAC addresses with IP addresses.

Answer 39

false

Question 40

For a TCP/IP datagram leaving a home network through a NAPT device, which of the following header fields (IP and/or TCP) are altered? (Check all that apply)

Answer 40

source port Source ip address Header checksum

Question 41

If an IP datagram is fragmented into 1000-byte fragments, and later encounters a link with an 800-byte MTU, it is dropped.

Answer 41

false

Question 42

The "Identification" header field is unchanged by IP datagram fragmentation.

Answer 42

true

Question 43

The IP header is encapsulated in IP datagram fragments.

Answer 43

false

Question 44

For the IPv4 CIDR address 146.10.150.116 /24 What is the... Netmask: Network Address: Host Mask: Broadcast Address: Number of possible hosts: 254 Host Number:

Answer 44

Netmask: 255.255.255.0 Network Address: 146.10.150.0 Host Mask: 0.0.0.255 Broadcast Address: 146.10.150.255 Number of possible hosts: 254 Host Number: 116

Question 45

A private network uses a NAPT device at public IP address 207.96.121.8 The computers in the network use addresses of the form 10.0.0.x/22. Suppose that computer inside the NATed network sends a request with Source address: 10.0.2.5 Source port: 750 Destination address: 128.193.4.20 Destination port: 60 The next available port number on the NAPT device is 12345. PART 1: What source and destination information do the request packet headers contain when the request is sent out by the sending host? Source address: Source port : Destination address: Destination port : PART 2: What source and destination information do the request packet headers contain when the request is sent out by the NAT box? Source address: Source port : Destination address: Destination port : PART 3: What source and destination information do the response packet headers contain when the response is received by the NAT box? Source address: Source port : Destination address: Destination port : PART 4: What source and destination information do the response packet headers contain when the response is received by the original sending host? Source address: Source port : Destination address: Destination port :

Answer 45

PART 1: What source and destination information do the request packet headers contain when the request is sent out by the sending host? Source address: 10.0.2.5 Source port : 750 Destination address: 128.193.4.20 Destination port : 60 PART 2: What source and destination information do the request packet headers contain when the request is sent out by the NAT box? Source address: 207.96.121.8 Source port : 12345 Destination address: 128.193.4.20 Destination port : 60 PART 3: What source and destination information do the response packet headers contain when the response is received by the NAT box? Source address: 128.193.4.20 Source port : 60 Destination address: 207.96.121.8 Destination port : 12345 PART 4: What source and destination information do the response packet headers contain when the response is received by the original sending host? Source address: 128.193.4.20 Source port : 60 Destination address: 10.0.2.5 Destination port : 750

Question 46

Suppose that a 2500-byte datagram (identification #23) must transit a network which has a 740-byte MTU. Assume the minimum IP and TCP header sizes, i.e., the IP header is 20 bytes and the TCP header is 20 bytes. How many fragments are created? fragments How many bytes of application data are carried in the first fragment? bytes How many bytes of application data are carried in the second fragment? 720 bytes How many bytes of application data are carried in the last fragment? bytes What is the identification number of the second fragment? # What is the fragment offset in the last fragment?

Answer 46

How many fragments are created? 4 fragments How many bytes of application data are carried in the first fragment? 700 bytes How many bytes of application data are carried in the second fragment? 720 bytes How many bytes of application data are carried in the last fragment? 320 bytes What is the identification number of the second fragment? # 23 What is the fragment offset in the last fragment? 270

Question 47

NAPT devices translate IP address and port numbers.

Answer 47

true

Question 48

If hosting a server inside a NATed network, how do clients outside the NAPT router connect to the server? (Check all that apply)

Answer 48

Correct! By using the NAPT devices IP address, and a port number pre-configured to correspond to the server. Correct! Using Universal Plug and Play (UPnP) Correct! Through a connection relay service

Question 49

The IP header is encapsulated in IP datagram fragments.

Answer 49

false

Question 50

The transport-layer header is encapsulated in the first fragmented IP datagram.

Answer 50

true

Question 51

The "time to live" field in a modern IPv4 datagram header specifies...

Answer 51

number of hops before datagram is dropped

Question 52

Network address translation alters IP to add new IP addresses.

Answer 52

False It doesn't add IP addresses, it just re-uses them.

Question 53

Re-assembly of fragmented IP datagrams is handled by...

Answer 53

the destination host.

Question 54

The IPv6 address size is 120 bits.

Answer 54

false

Question 55

In IPv6, there is no datagram fragmentation performed in the network core..

Answer 55

true

Question 56

Select all features explicit in IPv6 which are not explicitly available in IPv4.

Answer 56

Correct! 128-bit Addresses Correct! Payload Length Correct! Flow labeling Correct! Extension Headers

Question 57

The IPv6 address size is 128 bits.

Answer 57

true

Question 58

In IPv6, datagram fragmentation is handled at the network edge .

Answer 58

handled at the network edge

Question 59

1234:aac:a03::abcd is a valid preferred-format IPv6 address.

Answer 59

true

Question 60

1234::a03::abcd is a valid preferred-format IPv6 address.

Answer 60

false

Question 61

::ffff:ffff:fffff is a valid preferred-format IPv6 host address.

Answer 61

false It doesn't add IP addresses, it just re-uses them.

Question 62

Ethernet provides... error detection via CRC check

Answer 62

true

Question 63

t is fairly easy to detect collisions in wired networks.

Answer 63

true

Question 64

A switch is a network-layer device.

Answer 64

false

Question 65

For an machine using 2-dimensional even parity for error detection/correction, and the following received bytes, where is the error? If there is no error, select "No Error" for both boxes. Byte # Code Parity 1 1000 011 1 2 1000 110 0 3 1001 101 0 4 1100 011 0 5 1101 000 1 6 1100 110 0 7 1010 100 1 Parity 1111 001 1

Answer 65

Byte # 2 Bit # 4

Question 66

In a CSMA/CD system, when a collision is detected, …

Answer 66

the sender will cut off transmission and wait some time before retransmitting.

Question 67

The data-link layer provides logical communications between adjacent node and adjacent node .

Answer 67

true

Question 68

Given the following received byte on an odd-parity machine, there is definitely at least one error. 01001101

Answer 68

true

Question 69

When sending a message to all devices on a link, you would send it to the broadcast MAC address: 00-00-00-00-00-00

Answer 69

false

Question 70

Star Ethernet uses the same multiple access control as Bus Ethernet.

Answer 70

false

Question 71

Which are functions of the Ethernet preamble? (Check all that apply)

Answer 71

circuit wake-up Start signal Clock sync

Question 72

A MAC address is permanent and unique.

Answer 72

false

Question 73

The method by which a MAC protocol coordinates access to a broadcast medium to prevent and/or reduce collisions is most commonly called ________

Answer 73

multiple access

Question 74

A link-layer link between only two adjacent nodes is called a/an point to point link.

Answer 74

true

Question 75

A link-layer link between more than two adjacent nodes is called a/an broadcast link.

Answer 75

true

Question 76

It is fairly easy to detect collisions in wireless networks.

Answer 76

false It doesn't add IP addresses, it just re-uses them.

Question 77

Ethernet uses a RTS/CTS contention-free period.

Answer 77

false

Question 78

In an Ethernet network, after 8 collisions, the range of wait times will be …

Answer 78

[0, 1, ... 255] * 512 bit times

Question 79

When a mobile unit moves from a home or foreign agent to another (foreign) agent, the new agent must assign.... (Check all that apply)

Answer 79

a new “care-of” address to the mobile unit

Question 80

In indirect routing, after the initial contact with the home network, the correspondent sends packets to

Answer 80

The permanent address

Question 81

Which of the following are used in a wireless network such as 802.11n?

Answer 81

Correct! Exponential back-off/retry for collision resolution Correct! Carrier Sense Multiple Access Correct Answer Collision Avoidance Correct! Reservation system with Request to Send (RTS) and Clear to Send (CTS)

Question 82

The default multiple access scheme of 802.11g is RTS/CTS

Answer 82

false