1. UCCN1003 Data Communications and Networks
May 2010
Mid-Term Test 02 [Total: 100 marks]
Student ID : ______________________
Program : ______________________
Lab Instructor : ______________________
Practical Group # : ______________________
Multiple Choice Questions (Choose all that apply, including none of the above)
[22 questions, 2 marks each, Total = 44 marks]
1. All of the host in the above network are connected with each other via the managed switch.
Which of the following statements correctly describe the scheme of the network?
A) Subnet mask = 255.255.255.128
B) Subnet mask = 255.255.255.240
C) IP address 172.16.1.205 can be assigned to PCs in VLAN1
D) IP address 172.16.1.25 can be assigned to PCs in VLAN1
E) LAN Ethernet port of the router is configured with one IP address
F) LAN Ethernet port of the router is configured with multiple IP addresses
Answer:
2. A new switch is installed into an existing LAN and a new trunk is configured with an
existing switch. Which VLANs will be allowed on this new trunk?
A) All defined VLANs are allowed on the trunk by default.
B) Each VLAN, or VLAN range, that is specified with the switchport mode command.
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2. C) Each VLAN, or VLAN range, that is specified with the dot1q command.
D) Each VLAN, or VLAN range, that is specified with the vlan database command.
Answer:
3. What are some of the characteristics of a typical VLAN arrangement?
A) VLANs logically divide a switch into multiple, independent switches at Layer 2.
B) Trunk links can carry traffic for multiple VLANs.
C) VLAN implementation significantly increases traffic due to added trunking information.
D) A VLAN can span multiple switches.
E) VLANs typically increase the number of switches needed.
F) VLANs typically decrease the number of switches needed.
Answer:
4. How could a large corporation with many specialized divisions benefit from using VLANs
on their networks?
A) VLANs allow access to network services based on department, not physical location.
B) VLANs utilize packet filtering to enhance network security
C) VLANs provide a low-latency, high bandwidth internetworking alternative
D) VLANs provide a method of communication between IP addresses in large networks
E) VLANs establish segmented broadcast domains in switched networks
F) VLANs can greatly simplify adding, moving, or changing hosts on the network
Answer:
5. A college has a small campus where 25 lecturers are located. The faculty offices and student
computers are currently on the same subnet. The faculty is concerned about students being
able to capture packets going across the network and obtain sensitive material. What could a
network administrator do to protect faculty network traffic from student connections?
A) Install anti-virus software on student computers
B) Put the faculty computers in a separate VLAN
C) Power down the switches that connect to faculty computers when they are not in use.
D) Remove the student computers from the network and put them on a peer-to-peer network
E) Create an access list that blocks the students from the Internet where the hacking tools are
located.
Answer:
6. What are three valid reasons to assign ports on VLANs on a switch?
A) to make VTP easier to implement
B) to isolate broadcast traffic
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3. C) to increase the size of the collision domain
D) to allow more devices to connect to the network
E) to logically group hosts according to function
F) to increase network security
Answer:
7. A managed switch is configured with all ports assigned to VLAN 2. In addition, all ports are
configured as full-duplex FastEthernet. What is the effect of adding switch ports to a new
VLAN on this switch?
A) The additions will create more collisions domains
B) IP address utilization will be more efficient
C) More bandwidth will be required than was needed previously
D) An additional broadcast domain will be created
E) An additional broadcast domain will be created
F) The possibility that switching loops will occur will increase dramatically
Answer:
8. Refering to the above network, which of the follow statements correctly describe the switch
port configuration and the router port configurations?
A) The Router1 serial port is configured as a trunking port
B) The Router1 port connected to Switch1 is configured using sub-interfaces
C) The Router1 port connected to Switch1 is configured as 10Mbps
D) The Switch1 port connected to Router1 is configured as a trunking port
E) The Switch1 port connected to Host B is configured as an access port
F) The Switch1 port connected to Hub1 is configured as full duplex
Answer:
3

4. 9. Which of the following are true statements on the use of VLANs to segment a network?
A) They increase the size of collision domains.
B) They allow logical grouping of users by function.
C) They can enhance network security
D) They increase the size of the broadcast domain while decreasing the number of collision
domains.
E) They increase the number of broadcast domains while decreasing the size of the broadcast
domains.
F) They simplify switch administration
Answer:
10. In the above network, 802.1Q trunk is configured between a switch and a router. Which of
the following are valid configuration for the host shown in the network?
A) host A IP address: 192.1.1.65
B) host A subnet mask: 255.255.255.224
C) host B IP address: 192.1.1.125
D) host B default gateway: 192.1.1.65
E) host C IP address: 192.1.1.166
F) host C subnet mask: 255.255.255.224
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5. Answer:
11. Which is the following statements are the benefits associated with access control lists (ACLs)?
A) ACL monitor the number of bytes in the packets
B) ACL filter viruses and spam
C) ACL impede unnecessary services
D) ACL classifies and organizes network traffic
E) ACL provide high network availability
F) ACL provide IP route filtering
Answer:
12. When are packets being processed in an inbound access list?
A) Before the packets are routed to an outbound interface
B) After the packets are routed for outbound traffic
C) After the packets are routed to an outbound interface while queuing
D) Before and after the packets are routed on to an outbound interface
E) Depends on the configuration of the interface.
F) None of the above
Answer:
13. Which one of the ACL below will deny all telnet connections to subnet 10.10.1.0/24?
A) access-list 15 deny telnet any 10.10.1.0 0.0.0.255 eq 23
B) access-list 115 deny udp any 10.10.1.0 eq telnet
C) access-list 15 deny tcp 10.10.1.0 255.255.255.0 eq telnet
D) access-list 115 deny tcp any 10.10.1.0 0.0.0.255 eq 23
E) access-list 15 deny udp any 10.10.1.0 255.255.255.0 eq 23
Answer:
14. Which of the following statements are correct for named access list?
A) You can erase individual statements in a named access list
B) Named access lists required a list number range of 1000 to 1099
C) Name access lists must be specified as standard or extended
D) One can use the ip access-list command to create name access lists
E) One can’t erase individual statements in a named access list
F) You can use the ip name-group command to apply named access lists.
Answer:
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6. 15. In the above network, the Hong Kong router needs an access list that will accomplish the
following:
I) Allow a Telnet connection to the HR server via the Internet
II) Allow Internet HTTP traffic to access the Web Server
III) Block any other traffic from the Internet to everything else
Which of the following access list can perform the above goals?
A) access-list 101 permit tcp any 172.17.18.252 0.0.0.0 eq www
B) access-list 1 permit tcp any 172.17.17.252 0.0.0.0 eq telnet
C) access-list 101 permit tcp any 172.17.17.252 0.0.0.0 any eq telnet
D) access-list 101 deny tcp any 172.17.17.252 0.0.0.0 eq telnet
E) access-list 101 deny tcp any 172.17.18.252 0.0.0.0 eq www
F) access-list 101 permit tcp any 172.17.17.252 0.0.0.0 eq telnet
Answer:
16. You need an access list that will deny access to all hosts that lie in the range of
192.168.160.0 to 192.168.191.0. Hosts in the 192.168.195.0 network will be granted full
access. Which one of the following fulfills the requirement?
A) access-list 1 deny 192.168.163.0 0.0.0.255
B) access-list 1 deny 192.168.128.0 0.0.127.255
C) access-list 1 deny 192.168.160.0 0.0.255.255
D) access-list 1 deny 192.168.160.0 0.0.31.255
Answer:
17. You are the system administrator, and you create the following access list.
access-list 101 deny tcp 5.1.1.10 0.0.0.0 5.1.3.0 0.0.0.255 eq telnet
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7. access-list 101 permit any nay
You then enter the command “ip access-group 101 in” at the Ethernet port of Router0. Which
of the following telnet sessions will be blocked as a result of your access lists?
A) Telnet sessions from host A to host 5.1.1.10
B) Telnet sessions from host A to host 5.1.3.10
C) Telnet sessions from host B to host 5.1.2.10
D) Telnet sessions from host B to host 5.1.3.8
E) Telnet sessions from host C to host 5.1.3.10
F) Telnet sessions from host F to host 5.1.1.10
Answer:
18. Which of the following statements regarding the use of multiple access lists are valid when
configuring a single interface on a Cisco router?
A) Application of up to three access lists per protocol to a single interface
B) No more than two access lists per interface
C) One access list may be configured per direction for each layer 3 protocol configured on an
interface
D) The maximum number allowed varies due to RAM availability in the router
E) An infinite number of access list that can be applied to an interface, from most specific to
most general
F) Cisco IOS allows only one access list to an interface
Answer:
19. The following access list below was applied outbound on the fa0/0 interface connected to the
192.169.1.8/29 subnet.
access-list 135 deny tcp any 192.169.1.8 0.0.0.7 eq 20
access-list 135 deny tcp any 192.169.1.8 0.0.0.7 eq 21
How will the above access lists affect traffic?
A) FTP traffic from 192.169.1.22 will be denied
B) No traffic, except from FTP traffic will be allowed to exit fa0/0
C) FTP traffic from 192.169.1.9 to any host will be denied
D) All traffic exiting fa0/0 will be denied
E) All FTP traffic to network 192.169.1.9/29 will be denied
F) Telnet sessions from host F to host 5.1.1.10
Answer:
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8. 20. What are some general guidelines for the placement of ACL?
A) Standard ACLs should be placed as close as possible to the source of traffic to be denied
B) Extended ACLs should be placed as close as possible to the source of traffic to be denied
C) Standard ACLs should be placed as close as possible to the destination of traffic to be
denied
D) Extended ACLs should be placed as close as possible to the destination of traffic to be
denied
Answer:
21. A network administrator has configured an ACL 172 to prevent telnet and ICMP traffic from
reaching a server with an IP of 192.168.13.26. Which command can the administrator issue
to verify that the access list is working properly?
A) Router#ping 192.168.13.26.
B) Router#debug access-list 172
C) Router#show open ports 192.168.13.26
D) Router#show access-list
E) Router#show ip interface
Answer:
22. The following ACL needs to be applied to one of the routers shown in the above network.
access-list 101 permit tcp 192.168.1.16 0.0.0.15 192.168.2.16 0.0.0.15 eq 23
What can be concluded for this ACL?
A) Telnet traffic from 192.168.1.16 0.0.0.15 to 192.168.2.16 0.0.0.15 is allowed
B) SMTP traffic from 192.168.2.16 0.0.0.15 to 192.168.1.16 0.0.0.15 is allowed
C) The ACL is configured to allow traffic from one specific host to another
D) The ACL should be applied inbound to the Ethernet port of RouterA
E) The ACL should be applied outbound to the Ethernet port of RouterA
Answer:
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9. Problems [8 questions, total = 56 marks]
1. Based on the partial pathping result of Table 1, estimate the distance between 172.16.10.1
and 218.100.16.21 using the following criteria: [5 marks]
• The speed of signal traveled through the Internet medium is 2*108 m/s.
• Both 172.16.10.1 and 219.93.218.176 are in the same city. (negligible distance)
• There is router latency in 219.93.218.176 for both ways (to and fro).
• 218.100.16.21 is an efficient router (negligible latency).
c:>pathping 218.93.216.145
Computing statistics for 175 seconds…
Hop RTT Lost/Sent = Pct Lost/Send = Pct Address
0 acl127 [172.16.10.17]
0/ 100 = 0% |
1 0ms 0/ 100 = 0% 0/ 100 = 0% 172.16.10.1
0/ 100 = 0% |
2 0ms 0/ 100 = 0% 0/ 100 = 0% 218.93.190.45
0/ 100 = 0% |
3 28ms 0/ 100 = 0% 0/ 100 = 0% 219.93.218.176
0/ 100 = 0% |
4 46ms 0/ 100 = 0% 0/ 100 = 0% 218.100.16.21
0/ 100 = 0% |
...
Table 1
Answer:
9

10. 2. The following is the beginning 160 bytes of an Ethernet frame. Within this frame contains
part of an HTTP header. Please find the embedded URL inside the frame (Answer example:
http://www.cnn.com/news.html). [6 marks]
00 0e d7 ec 76 80 00 20 ed 78 85 31 08 00 45 00
01 d0 52 10 40 00 80 06 19 a7 c0 a8 09 1f c0 a8
03 01 11 fa 1f 90 09 a2 40 e9 57 b5 d9 e1 50 18
43 dd 8c c1 00 00 47 45 54 20 68 74 74 70 3a 2f
2f 77 77 77 2e 67 6c 6f 62 61 6c 72 65 73 65 61
72 63 68 2e 63 61 2f 33 63 6f 6c 5f 6c 65 66 74
4e 61 76 2e 63 73 73 20 48 54 54 50 2f 31 2e 31
0d 0a 48 6f 73 74 3a 20 77 77 77 2e 67 6c 6f 62
61 6c 72 65 73 65 61 72 63 68 2e 63 61 0d 0a 55
73 65 72 2d 41 67 65 6e 74 3a 20 4d 6f 7a 69 6c
.......
Answer:
3. The following Ethernet frame contains a TFTP option acknowledgement. What is the tsize
and blksize? (Hint: A little research in the Internet will be useful) [7 marks]
00 0d 87 df 79 dc 00 50 ba c2 e0 d4 08 00 45 00
00 39 35 b5 40 00 40 11 70 56 ac 10 1e 46 ac 10
1e 42 80 12 04 4d 00 25 3b d6 00 06 74 73 69 7a
65 00 35 38 39 33 37 36 00 62 6c 6b 73 69 7a 65
00 31 32 32 35 30 00
Answer:
10

11. 4. Fill in the appropriate number for the blanks in “Seq =” and “Ack =” for the following TCP
flow graph. Start with Seq=0 and Ack=0 for the first line (SYN). [16 marks]
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12. 5. Write one signal formula, based on the following frequency domain display. [4 marks]
Amplitude/volts
3
8 18
f/Hz
Answer:
6. Based on Figure 1(a).1 and Figure1(a).2, list all the IP addresses that can be assigned to PC0,
so that PC0 can ping either PC1 or PC2. [8 marks]
Figure 1(a).1
!
hostname Router0
!
interface FastEthernet0/0
ip address 10.1.1.254 255.255.255.0
no shutdown
!
interface FastEthernet0/1
ip address 192.168.1.254 255.255.255.0
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13. ip access-group 10 out
no shutdown
!
interface FastEthernet1/0
ip address 172.16.1.254 255.255.255.0
ip access-group 11 out
no shutdown
!
access-list 11 permit 10.1.1.0 0.0.0.52
access-list 10 permit 10.1.1.2 0.0.0.73
!
Figure 1(a).2
Answer:
For PC0 to PC1:
For PC0 to PC2:
7. What is the maximum transmission efficiency for an Ethernet frame that contains an UDP
segment, assuming the Ethernet frame overhead as 16 bytes. (Hint: transmission efficiency =
[Data/(Data+Overheads)]) [6 marks]
Answer:
13

14. 8. There are 8 lines in the following HTTP message. State the line (e.g. first line, second line,
etc) that contain an error and briefly describe the error. [4 marks]
GET http://www.google.com.my/images/nav_logo.gif HTTP/1.1rn
Content-Length: 3357
Date: Tue, 27 Feb 2007 11:02:41 GMTrn
Age: 668rn
Content-type: image/gifrn
Server: Netscape-Enterprise/6.0rn
Last-modified: Mon, 27 Dec 2004 14:49:47 GMTrn
Accept-ranges: bytesrn
rn
Answer:
14