UNIVERSIDADE DA BEIRA INTERIOR Faculdade de Engenharia Departamento de Informática

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1. This is a frequency evaluation test.

2. Read the questions carefully before answering. 3. Write your answers in the answer sheet provided.

4. Return only the answer sheet with your name, number and course name.

5. The grading grid is at the end of the test. Good work!

SINGLE GROUP – in the following questions, please choose only one option.

1. Consider the image above. How many subnetworks are shown? a) One, identified by the address 192.168.0.0/24

b) One, , identified by the address 192.168.100.0/24

c) Two, identified by the addresses 192.168.0.0/24 and 192.168.100.0/24

d) None because the computers run an operationg system that is too old to use networks e) None of the above options

2. Regarding the scheme used in question 1, which of the following statements is true?

a) The MAC address of the Modem has to be different from the MAC address of the remaining elements in the network

b) The machine with the address 192.168.0.4 cannot use the PING command to determine if the Modem is on c) The Windows machines and the Router/Switch have to be in the same network of the Modem to be able to access

Internet

d) To configure correctly the network the Router/Switch can only have addresses from one subnet e) All the above

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3. For the scheme above, what would be the network mask for Network A? a) 255.255.255.255

b) 255.255.255.0

c) 255.255.0.0 d) 255.0.0.0 e) Any of the above f) None of the above

4. Regarding the scheme for question 3 how many subnetworks can you identify between the final host and the Internet Modem?

a) 1 b) 2

c) 3

d) 4

e) None of the above

5. Regarding the scheme for question 3, hwo many interfaces has the machine identified as “XP Router” (at least)? a) 1

b) 2

c) 3

d) 4

e) One can not tell, that information is not visible on the scheme f) None of the above

6. Regarding the scheme in question 3, which of the follwoing claims is true? a) All the computers and active equipments have different MAC addresses

b) All the network interfaces in the “XP Router” machine have the same MAC address

c) The machine with the 10.10.10.50 address may have the same MAC address of the machine with the 192.168.20.100 address

d) The machine with the 10.10.10.50 address must have a MAC address that is different of all the machines it communicates with

e) All of the above f) None of the above

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7. Regarding the addresses of Layer 3, what of these claims is true? a) These are physical addresses

b) These are addresses used in routing decisions

c) There are addresses used only in local networks

d) There are addresses changed each time a packet is passes in a Switch e) All of the above

f) None of the above

8. A network defined as 192.168.1.0/24 has a network mask: a) 255.255.255.255

b) 255.255.255.0 c) 255.255.0.0 d) 255.0.0.0

e) It may have any valid network mask defined by the user f) None of the above

9. A network defined as 10.0.0.0/24 may have

a) 254 hosts

b) 256 hosts c) 65534 hosts d) 65536 hosts

e) The number of hosts is not a function of this information f) None of the above

10. Supose you have the address 192.168.8.0/22. Which of these informations is correct? a) You can create 4 networks with address 192.168.x.0/24, x < 8

b) You can create 4 networks with address 192.168.x.0/26, x < 8

c) You can create 4 networks with address 192.168.x.0/24, x>=8

d) You can create 4 networks with address 192.168.x.0/26, x>=8 e) None of the above

11. When you try to use the command “ping 127.0.0.1” you receive an error messge. Probably this mean that: a) Your computer is disconnected from the network

b) The computer’s network interface is not correctly configured

c) The protocol stack is not correctly working

d) The command is not correct e) None of the above

12. Regarding the scheme above, the computer PC1 is able to access contents in computer PC2 using Telnet. This means that:

a) Routers A and B are configured in the same subnetwork b) The IP addresses for interfaces S0 and S1 are the same c) PC1 is in the same subnetwork as PC2

d) PC2 is running a Telnet server

e) All of the above f) None of the above

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13. What network mask admits 2040 hosts in network 10.0.0.0? a) 255.255.0.0 b) 255.255.254.0 c) 255.255.252.0 d) 255.255.248.0 e) 255.255.255.240 f) None of the above

14. Following the convention, what of the next network masks is adequate for a Class B network? a) 255.255.255.0

b) 255.255.0.0 c) 255.0.0.

d) it depents on the number of computers you want to define e) none of the above

15. Following the convention, the address 172.16.3.1 is: a) Public, Class C

b) Private Class C c) Public, Class B

d) Private, Class B

e) It depends on the defined network mask f) None of the above

16. The address 49.22.201.70 (Class A) identifies: a) host 70 of network 49.22.201

b) host 201.70 of network 49.22

c) host 22.201.70 of network 49

d) None of the above.

17. Concerning private IP addresses, which of the following statements is false?

a) A network router may be responsible to distribute dynamic IP addresses using the DHCP protocol

b) A host can only use a private address if it is connected to the Internet

c) A computer may change its IP address dynamically d) A private address has to be unique in its network

18. Concerning public IP addresses, which of the following statements is false? a) A host may use a public address as long as it is in an isolated netork b) A host may use a public IP address in the Internet

c) Each host connected to the Internet must have its own public address

d) The management of public IP addresses is done differently from private addresses

19. If in the laboratory we define two networks with the addresses 192.168.1.0/24 and 192.168.2.0/24, which of these claims is false?

a) Each of these networks may have 240 hosts

b) Computers in one network will not be able to communicate with computers in the other network

c) Computers in one network are able to communicate with the computers in the other

d) Inside the class these networks belong to, it is possible to define other subnetworks

20. Consider the Class C 192.168.0.0/24 network. Besides this one can further define ___ subnetworks. a) 256

b) 255 c) 254

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21. Consider the above scheme. Computer C can execute with success the command “ping 127.0.0.1”, but not the command “ping 172.16.31.98”. This is because:

a) Computers A and B are not in the same network as computer C b) IP addresses in Fa0/1 interfaces in routers 1 and 2 are wrong

c) The network mask for computer C is wrong

d) Interface Fa0/0 in router 2 is not properly configured e) None of the above

22. Consider the scheme above. What would be an appropriate IP address for computer A?

a) 192.168.100.28 b) 192.168.100.20 c) 192.168.100.30

d) 192.168.100.31 e) none of the above

23. Consider the scheme for question 22. What would be an appropriate network mask to apply to computer A? a) 255.255.0.0

b) 255.255.255.0

c) 255.255.255.240

d) 255.255.255.248 e) none of the above

24. Consider the scheme in question 22. What would be the gateway to define for computer A? a) 192.16.1.2

b) 192.168.100.17

c) 192.168.1.0 d) 10.1.1.5

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25. A computer can not connect to remote computers, nor connect to the Internet, nor use a network printer that is working in the network. What command must be used to test if the network components are properly installed? a) Ipconfig /all

b) Ping 127.0.0.1

c) traceroute

d) none of the above

26. Consider the scheme above. Which of the statements is true?

a) Printers 10.0.0.253 and 10.0.1.253 can only be used by computers in its respective networks b) Printers have wrong addresses because higher addresses are used for broadcast

c) Computer 10.0.1.1 only can use printer 10.0.1.253

d) Computer 10.0.0.1 can use printer 10.0.1.253 if the routers are properly configured

e) None of the above

27. Which of these addresses is valid for a computer in a subnetwork? a) 10.1.11.128/27

b) 10.1.12.79/28 c) 10.1.12.32/28

d) 10.1.11.97/27

e) All of the above f) None of the above

28. Consider the figure above. In this network only a switch is available. If the address 192.168.34.1 is a gateway with access to the Internet, can this computer access the Internet?

a) Yes, because the network mas places the gateway in the same network as this computer. b) Yes, because the gateway allows the sharing of contents from the Internet

c) No, because the configuration is not dynamic

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29. Given the address 192.168.1.0, what is the mask that allows to have exactly 8 subnetworks? a) 255.255.252.0

b) 255.255.255.0 c) 255.255.255.252

d) 255.255.255.224

e) None of the above

30. The binary operation performed with the network mask and the IP address is a) A sum

b) AND

c) OR d) EXOR

e) None of the above

Grading grid

Each question is worth 0.6(6) (2/3) values.

Incorrect answers are graded with -50% of 2/3.

Prof. Nuno M. Garcia, January 2011

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