Al's CCENT Practice Test #3

Revised June 27, 2018

(If you find any errors, let me know!)

1. Which was the creator of the Internet?

  1. ARIN
  2. ARPA
  3. IETF
  4. Albert Gore, Jr.
  5. Mr. Spock

2. From which sources can configuration information be obtained?

  1. Console port
  2. Telnet via vty ports
  3. HTTP/HTTPS or SNMP
  4. Auxiliary port
  5. TFTP
  6. All of the above.

3. What is the function of the OSI "Application" layer?

  1. It contains the user application.
  2. It controls access to the media and performs packet encapsulation.
  3. It provides an interface between the network stack and the host's operating system, allowing use of network services.
  4. It performs compression, encryption and/or other data formatting.
  5. All of the above.
  6. None of the above.

4. Which of the following would be an acceptable banner in a business environment?

  1. Router1(config)#banner login ### Welcome to our Double-Top-Secret Multi-Layer Switch! ###
  2. Router1(config)#banner login *** This is private property! Stay the #*&@$ out! I've got a gun! ***
  3. Router1(config)#banner login <><><> Warning! Entry by authorized personnel only! <><><>
  4. Router1(config)#banner login >>>> The password on this router has been changed to "Ci$co" <<<<<
  5. Router1(config)#banner login /\/\/\ We know who you are. We know where you live. You'll be sorry! /\/\/\
  6. Router1(config)#banner login @-@-@ To give Al a mild electric shock, press any key! @-@-@

5. Which protocol's port numbers have more bits, TCP or UDP?

  1. TCP
  2. UDP
  3. TCP uses port numbers, but UDP doesn't.
  4. Neither, they both use 16-bit port numbers.
  5. Neither, they both use 32-bit port numbers.
  6. Neither a TCP nor a UDP header contains port numbers, they have protocol numbers.

6. Which switching option forwards the frame immediately after the sixty-fourth byte is received?

  1. Ad-hoc
  2. Cut-through
  3. Fragment-free
  4. Store-and-forward
  5. Full-duplex

7. Given the following CLI syntax, what command was used to move from the first prompt to the second? 

  Router1>command
  Router1#
  1. login
  2. enable
  3. config-register
  4. configure terminal
  5. service password-encryption

8. Which of the following might be adversaries attempting to illicitly access the network?

  1. Disgruntled employees.
  2. Terrorists.
  3. Nation-states.
  4. Your own government.
  5. Your own CEO.

9. Which command will display the number of CRC errors on an Ethernet port?

  1. show crc
  2. show fcs
  3. show errors
  4. show interface
  5. show ip interface

10. What is the purpose of a computer network?

  1. To share information and resources.
  2. To expend RAM, bandwidth and CPU cycles.
  3. To share information and resources with hackers.
  4. To reduce shareholder value by squandering corporate financial resources.

11. With regard to OFDM and DSSS, which provides higher data rates on WLANs?

  1. DSSS
  2. OFDM
  3. The data rate is independent of the encoding scheme.
  4. WLANs use Manchester encoding, not OFDM or DSSS.

12. If your IEEE 802.11b/g WLAN access point is operating at maximum legal power, what could you do to increase the range in a given direction?

  1. Install a linear amplifier between the access point and the antenna.
  2. Use a directional antenna.
  3. Use lead-based wall and ceiling paint to reduce the effects of attenuation, reflection and scattering.
  4. Place aluminum foil around the receiver's antenna on the side of the transmitter.
  5. Use the "reload" privileged-mode command on the access point.
  6. Nothing. You're out of luck.

13. Which of the following are true regarding TCP?

  1. The port numbers specify the application.
  2. The "SYN" bit signals the desire to synchronize on a beginning sequence number.
  3. The "ACK" bit signals that the acknowledgement field is valid.
  4. The "FIN" bit signals that the session is complete.
  5. The "RST" bit signals an error, terminating the session.
  6. All of the above.
  7. None of the above.

14. What is the purpose of the "description" command in interface configuration mode?

  1. To inform the router or switch of the relative importance of the hosts on that interface.
  2. To tell the router or switch what type (ATM, Ethernet, Serial, etc) the interface is.
  3. To provide documentation for humans (which the router or switch ignores).
  4. To give the router or switch information for CDP advertisements.

15. Given the following CLI syntax, what command was used to move from the first prompt to the second? 

  Router1(config)#command
  Router1(config-line)#
  1. router rip
  2. line console 0
  3. configure terminal
  4. controller serial1/0
  5. interface fastethernet0/1

16. How many layers are there in the OSI model?

  1. 1
  2. 4
  3. 7
  4. 9
  5. That information is classified.

17. Which of the following might interfere with WLAN transmissions?

  1. Brain waves
  2. Cordless phones
  3. Microwave ovens
  4. Rogue access points
  5. Ad hoc networks

18. Without resorting to the techniques of RFC-1323 (TCP Extensions for High Performance), what is the maximum window size?

  1. 255 packets
  2. 1024 bytes
  3. 16,384 packets
  4. 65,535 bytes
  5. Unlimited

19. Which of the following is an example of "jabber"?

  1. A politician with his mouth open.
  2. A switch that floods broadcast frames.
  3. A router that exchanges RIP updates with a neighbor.
  4. A NIC that continually sends random bits.
  5. An instructor who tells you everything he knows and more.

20. Which of the following are components of a network?

  1. Computers
  2. NICs
  3. Media
  4. Routers and switches
  5. All of the above.

21. The SPF algorithm works by building a shortest-path ______________ from which the routing table is obtained.

  1. Forest
  2. Shrub
  3. Vine
  4. Tree
  5. None of these, the routing table is constructed by the spanning-tree algorithm (STA).

22. Which layer of the OSI model is tasked with reliability?

  1. Layer 1
  2. Datalink
  3. Internet
  4. Transport
  5. Layer 5
  6. Some other layer.

23. IEEE 802.11 WLANs use "CSMA/CA". What does the "CA" represent?

  1. Carrier arbitration.
  2. Constant attenuation.
  3. Conjugate amplitudes.
  4. Co-axial asymptotes.
  5. Collision avoidance.

24. What are the default port numbers for FTP-data, TFTP, Telnet and HTTP, respectively?

  1. UDP 20, TCP 69, UDP 23 and UDP 80.
  2. TCP 20, UDP 69, TCP 23 and TCP 80.
  3. TCP 23, UDP 69, TCP 21 and TCP 80.
  4. TCP 80, UDP 69, TCP 23 and TCP 80.
  5. TCP 20, UDP 69, TCP 23 and TCP 8080.
  6. None of the above.

25. Why should networking equipment (such as routers, switches and firewalls) be kept behind locked doors?

  1. To prevent theft.
  2. To prevent sabotage.
  3. To prevent accidental damage.
  4. To prevent unauthorized access to the console port (password recovery).
  5. All of the above.

26. How many links are required for a full-mesh topology with 60 nodes?

  1. 30
  2. 60
  3. 255
  4. 1,770
  5. 65,536
  6. It cannot be determined without drawing an incredibly messy diagram and counting the links.

27. Which of the following are OSI Layer-2 capable devices?

  1. Cat-5 cable with RJ-45's
  2. Repeater
  3. Bridge
  4. Hub
  5. Switch
  6. Router
  7. NIC
  8. Multi-layer switch

28. Which of the following can the SDM perform?

  1. Configure routing protocols.
  2. Configure interfaces.
  3. Configure VPN service.
  4. Configure DHCP.
  5. Monitor router operations.
  6. Telepathic configuration.

29. If Host1 sends a TCP segment with a sequence number of 123, how would Host2 acknowledge it?

  1. It will send a TCP segment to Host1 with a value of 123 in the sequence number field.
  2. It will send a TCP segment to Host1 with a value of 123 in the acknowledgement field.
  3. It will send a TCP segment to Host1 with a value of 124 in the sequence number field.
  4. It will send a TCP segment to Host1 with a value of 124 in the acknowledgement field.
  5. It will send an ICMP "segment_received" message containing the value "124" to Host1.
  6. Since TCP is connectionless, it doesn't send acknowledgements.

30. Which command displays the MAC address of a Windows PC?

  1. ipconfig
  2. ipconfig/all
  3. show interface
  4. show mac-address
  5. Any of the above.

31. How are radio waves coupled into the air?

  1. With a speaker.
  2. With an antenna.
  3. With a microphone.
  4. With an RJ-45 interface.
  5. On a wing and a prayer.

32. Which command displays whence IOS was loaded?

  1. show ios
  2. dir flash:
  3. show flash
  4. show whence
  5. show version

33. What is meant by "connection-oriented" with regard to TCP?

  1. TCP negotiates to ensure that both hosts have sufficient resources to support the session.
  2. TCP requires the use of Permanent Virtual Circuits for WAN connections.
  3. TCP offers the option of up-front negotiation (but rarely makes use of it).
  4. TCP
  5. TCP takes total control of the entire Internet for the duration of the session.

34. Given the following CLI syntax, what command was used to move from the first prompt to the second? 

  Router1#command
  Router1(config)#
  1. router rip
  2. line console 0
  3. clock rate 64000
  4. configure terminal
  5. interface fastethernet0/1

35. When can a "/31" mask be used?

  1. On subnets of class "C" networks that require up to 126 hosts per subnet.
  2. On point-to-point links, which require only two hosts.
  3. Only on private networks.
  4. Never, it's forbidden by RFC 3021.

36. What is a "PSK"?

  1. Perimeter Security Knowledge (a protocol for keeping the bad guys away)
  2. Pre-Shared Key (the "password" that has to be kept secret)
  3. Private Secret Konfidential (a Russian encryption protocol)
  4. People Shouldn't Know (a U.S. encryption protocol)

37. What does the command "show mac-address-table" display?

  1. Interfaces, associated MAC addresses, and associated VLANs.
  2. IP addresses, associated subnets, and associated default gateways.
  3. TCP/UDP ports, associated applications, and associated header checksums.
  4. None of the above.

38. Which is the correct sequence of operations when sending packets from one host to another?

  1. ARP lookup, packet is encapsulated, packet sent from Layer-3 to Layer-2, frame dispatched from interface onto media.
  2. Packet is encapsulated, packet sent from Layer-3 to Layer-2, frame dispatched from interface onto media, ARP lookup.
  3. Packet sent from Layer-3 to Layer-2, ARP lookup, packet is encapsulated, frame dispatched from interface onto media.
  4. Packet sent from Layer-3 to Layer-2, packet is encapsulated, frame dispatched from interface onto media, ARP lookup.
  5. Frame dispatched from interface onto media, packet is encapsulated, ARP lookup, packet sent from Layer-3 to Layer-2.

39. If a host's address is 172.25.101.114, and its subnet mask is 255.255.255.248, which of the following could be the address of its default gateway?

  1. 172.25.101.0
  2. 172.25.101.112
  3. 172.25.101.117
  4. 172.25.101.119
  5. 172.25.101.248
  6. 172.25.101.249
  7. None of the above.

40. Which of the following are private class B networks?

  1. 10.0.0.0
  2. 125.1.0.0
  3. 127.0.0.1
  4. 151.28.0.0
  5. 172.20.0.0
  6. 172.31.128.0/24
  7. 192.168.255.0
  8. 239.73.0.0

41. The higher the frequency, the ____________ the wavelength.

  1. Longer.
  2. Shorter
  3. Louder.
  4. Redder.
  5. Doppler.
  6. None of the above.

42. With regard to the OSI model, what is meant by "peer-to-peer"?

  1. Clients communicating with servers.
  2. A layer in the stack communicating with the layers above and below.
  3. A particular layer in one device's stack communicating with the corresponding layer in another device's stack.
  4. This concept is not used in the OSI model.

43. Which of the following is a hardware threat?

  1. High humidity.
  2. Sledgehammer-wielding networking instructor.
  3. A backhoe cross-connecting a 2000 volt line with the 120 volt line.
  4. Failure of on-board flash memory without spare flash SIMMs available.
  5. All of the above

44. How is a client's UDP source port number usually determined for most applications?

  1. It is negotiated between the hosts.
  2. It is hard-wired into the client software.
  3. It is assigned by the great and powerful IT staff.
  4. It is chosen by the transport layer of the protocol stack.
  5. Only servers use differing source port numbers, client source ports are always set to zero.

45. Which of the following are OSI Layer-3 capable devices?

  1. Cat-5 cable with RJ-45's
  2. Repeater
  3. Bridge
  4. Hub
  5. Switch
  6. Router
  7. NIC
  8. Multi-layer switch

46. What is the sequence of fields in the Ethernet frame type typically used to encapsulate IP?

  1. Preamble, source MAC, destination MAC, Ethertype, data, FCS.
  2. Preamble, Ethertype, destination MAC, source MAC, data, FCS.
  3. Preamble, data, destination MAC, source MAC, Ethertype, FCS.
  4. Preamble, destination MAC, source MAC, Ethertype, data, FCS.
  5. Preamble, destination MAC, source MAC, Ethertype, data, FCS, postamble.
  6. Preamble, SOF delimeter, destination MAC, data, source MAC, Ethertype, FCS.

47. Given the following CLI syntax, which commands could be used to move from the first prompt to the second? 

  Router1(config-if)#command
  Router1#
  1. end
  2. exit
  3. logout
  4. disable
  5. no configure terminal
  6. <CTRL> Z

48. Which of the following are types of applications?

  1. Batch
  2. Bug-ridden
  3. Interactive
  4. Unsupported
  5. Pipelined
  6. Real-time

49. As compared to a bridge, a modern LAN switch offers which of the following?

  1. Higher port density.
  2. Rate adaptation.
  3. Full-duplex capability.
  4. Larger frame buffers.
  5. Greater throughput.
  6. VLANs.
  7. Port security.
  8. All of the above.

50. What could be a problem when designing/installing an IEEE 802.11b/g WLAN system in a multi-story building?

  1. With only three channels, you can only have three access points per WLAN system.
  2. Since 802.11b/g equipment is more expensive than 802.11a equipment, cost is a factor.
  3. With only three channels, it's hard to keep cells on the same channels from overlapping.
  4. There are no problems, things are just as easy as with a single-story building.

ANSWERS 

 1. B       11. B       21. D       31. B       41. B
 2. F       12. B       22. D       32. E       42. C
 3. C       13. F       23. E       33. A       43. B
 4. C       14. C       24. B       34. D       44. D
 5. D       15. B       25. E       35. B       45. FH
 6. C       16. C       26. D       36. B       46. D
 7. B       17. BCDE    27. CEFGH   37. A       47. AF
 8. ABCD    18. D       28. ABCDE   38. C       48. ACF
 9. D       19. D       29. D       39. C       49. H
10. A       20. E       30. B       40. E       50. C

NOTES
1. Al Gore didn't "invent" it, but he did arrange for us to pay for it. For details, see the High-Performance Computing Act of 1991. Good job, Al!
4. "F" was used by some clever students of mine in a CCNA class back in 1999.
6. Assuming CSMA/CD is working correctly, there shouldn't be any collisions after the sixty-fourth byte ("late collisions"), thus the downstream link should be free of forwarded fragments generated by upstream collisions.
9."CRC" (Cyclic Redundancy Check) is the algorithm to calculate the Ethernet FCS (Frame Check Sequence).
16. Some people claim it has nine layers, with the upper two being "Politics" and "Religion".
26. The formula for calculating the number of links in a full mesh is: n(n-1)/2, where "n" is the number of nodes. In this case, that would be 60(60-1)/2 = 60(59)/2 = 3540/2 = 1770.
27. If a device is "Layer-X capable", then it understands all of the layers up to and including Layer-X.
31. Yeah, I know ... technically, "the air" has nothing to do with it, but it makes for a convenient analogy with sound waves.
35. See RFC 3021 for details.
39. With a mask of 255.255.255.248 (/29), the subnets increment by eight, so the address 172.25.101.114 is on the 172.25.101.112/29 subnet, and the next subnet is 172.25.101.120/29. The range of legal host address on the "112" subnet is 113 through 118 (since 112 is the subnet, and 119 is the broadcast for that subnet). Thus, the host's default gateway's address must be in the range from 172.25.101.113 through 172.25.101.118, and only "C" falls within that range.
40. "A" isn't class "B". "B" isn't class "B", and it's a subnet, not a network. "C" is resevered ("loopback"). "D" is a class "B", but it isn't private. "F" is in the private class "B" space, but it's a subnet (not a network). "G" is private, but it's class "C". "H" is a class "D" (multicast) address.
41. When it comes to visible light, the higher the frequency, the bluer it is.
43. "A" is an environmental threat, "C" is electrical, "D" is maintenance.
44. For most applications, the UDP (and TCP) client port numbers are generally picked by the stack, in the range from 1024 through 65,535. 48. I realize that applications may be bug-ridden and/or unsupported, but those weren't mentioned in Cisco's courseware.
50. In a multi-story building, you're operating in three dimensions, so it can be difficult to arrange the access points to provide full coverage (overlapping the different channels, while not overlapping the same channels).

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