1. Chapter 12
True/False
Indicate whether the statement is true or false.
____ 1. Routers, switches, bridges, and gateways segment networks and thus create separate collision domains.
____ 2. When a segment has too much broadcast traffic, utilization increases and network performance in general
benefits.
____ 3. IEEE 802.3u specifies two types of repeaters: Class I and Class II. Class II repeaters have higher latency than
Class I repeaters.
____ 4. The main difference between a switch and a bridge is that the switch typically connects multiple stations indi-
vidually, thereby segmenting a LAN into multiple collision domains.
____ 5. You cannot actually configure a router until you get to enable mode.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 6. A(n) ____ is the physical area in which a packet collision might occur.
a. backoff domain c. IPG domain
b. collision domain d. jam domain
____ 7. Stations on a network ____ packets to other stations to make their presence known on the network and to car-
ry out normal network tasks such as IP address-to-MAC address resolution.
a. broadcast c. multicast
b. unicast d. anycast
____ 8. ____ refers to the amount of time required to transmit one data bit on a network.
a. Transmission time c. Latency
b. Slot time d. Bit time
____ 9. ____ specifies that all collisions should be detected from anywhere in a network in less time than is required
to place a 64-byte frame on the network.
a. Latency c. Slot time
b. Transmission time d. Bit time
____ 10. A ____ error indicates that bits of a frame were corrupted during transmission,
a. frame check sequence (FCS) c. long frame
b. jabber d. short frame
____ 11. A(n) ____ occurs when two stations transmit more than 64 bytes of data frames before detecting a collision.
a. jabber c. late collision
b. NIC error d. alignment error
____ 12. A bridge maintains a ____ that maps the MAC addresses on each segment to the corresponding port on the
bridge to which each segment is connected.
a. multicast table c. bandwidth table
b. map table d. bridging table

2. ____ 13. A ____ operates at layer 3 of the OSI reference model. It interprets the Network layer protocol and makes for-
warding decisions based on the layer 3 address.
a. switch c. bridge
b. router d. hub
____ 14. In ____ memory buffering, each port has a certain amount of memory that it can use to store frames.
a. exclusive c. port-based
b. shared d. content-addressable
____ 15. With ____ memory buffering, any port can store frames in the shared memory buffer.
a. content-addressable c. port-based
b. shared d. exclusive
____ 16. Some switches can interconnect network interfaces of different speeds. These switches use ____ switching
and, typically, a shared memory buffer.
a. symmetric c. virtual
b. shared d. asymmetric
____ 17. Switches that use ____ forwarding start sending a frame immediately after reading the destination MAC ad-
dress into their buffers.
a. cut-through c. fragment-free
b. store-and-forward d. adaptive cut-through forwarding
____ 18. ____ switches read the entire frame, no matter how large, into their buffers before forwarding.
a. Fast-forward c. fragment-free
b. Store-and-forward d. cut-through
____ 19. ____ represents an effort to provide more error-reducing benefits than cut-through switching, while keeping
latency lower than does store-and-forward switching.
a. Fragment-free forwarding c. Adaptive cut-through forwarding
b. Fast forwarding d. Adaptive fast forwarding
____ 20. Fragment-free switches are also known as ____ switches.
a. fast forwarding c. cut-through
b. error sensing d. modified cut-through
____ 21. Two types of operating systems are in use on Cisco switches: IOS-based and ____.
a. terminal-based c. set-based
b. command-based d. prompt-based
____ 22. To enter enable mode, type ____ at the command-line prompt and then press Enter.
a. enable c. enable on
b. mode -enable d. set enable
____ 23. To start configuration mode, first type ____ at the command prompt.
a. cfg trmnl c. config t
b. config tty d. cfg t
____ 24. Generally speaking, a switch does not require an IP address, because switches operate mainly on Layer 2
(____ addresses).
a. IP c. IPX
b. TCP d. MAC

3. ____ 25. To view the configuration of a port, use the ____ command.
a. display c. interface
b. show d. port
____ 26. Cisco uses the term ____ to refer to the process by which a switch learns addresses on its own.
a. ipg learn c. sticky learn
b. switch learn d. sticky memory
Completion
Complete each statement.
27. ____________________ is a network access method (or media access method) originated by the University
of Hawaii, later adopted by Xerox Corporation, and standardized as IEEE 802.3 in the early 1980s.
28. The amount of time it takes for a packet to be sent from one device to another is called the
____________________.
29. In ____________________ communications, devices can send and receive signals, but not at the same time.
30. In ____________________ communications, devices can send and receive signals simultaneously.
31. The MAC-to-switch-port mapping is stored in the switch’s ______________________________.
Matching
Match each item with a statement below:
a. CSMA/CD f. Bridge
b. Broadcast storm g. Symmetric switching
c. Latency h. Adaptive cut-through forwarding
d. 5-4-3 rule i. VLAN
e. Alignment error
____ 32. a frame with an FCS error and an octet missing
____ 33. virtual local area network that allows you to logically segment a network
____ 34. switches that require all attached network interface devices to use the same transmit/receive speed
____ 35. a sudden rush of network transmissions that causes all other network communications to slow down due to
the volume of data competing for access to the same bandwidth on the communications medium
____ 36. segments a network by filtering traffic at the Data Link layer
____ 37. the length of time that is required to forward, send, or otherwise propagate a data frame
____ 38. also known as error sensing
____ 39. limits collision domains to five segments of wire, four repeaters and/or hubs, and three populated hubs be-
tween any two stations on a 10-Mbps network
____ 40. Ethernet contention method

4. Short Answer
41. How are collisions handled by CSMA/CD?
42. Describe a simple way to reduce broadcast traffic.
43. What are some of the frame size errors that occur on Ethernet networks?
44. What are the three defined implementations of Fast Ethernet?
45. What are the Gigabit Ethernet specifications and the governing IEEE standards?
46. What are the benefits of using full-duplex?
47. What are the benefits provided by switches?
48. Describe cut-through forwarding switching.
49. How can you set the host name on a Cisco Catalyst switch?

5. 50. Describe the violation command for configuring port security.
Chapter 12
Answer Section
TRUE/FALSE
1. ANS: T PTS: 1 REF: 338
2. ANS: F PTS: 1 REF: 339
3. ANS: F PTS: 1 REF: 342
4. ANS: T PTS: 1 REF: 346
5. ANS: T PTS: 1 REF: 351
MULTIPLE CHOICE
6. ANS: B PTS: 1 REF: 338
7. ANS: A PTS: 1 REF: 339
8. ANS: D PTS: 1 REF: 340
9. ANS: C PTS: 1 REF: 340
10. ANS: A PTS: 1 REF: 341
11. ANS: C PTS: 1 REF: 341
12. ANS: D PTS: 1 REF: 345
13. ANS: B PTS: 1 REF: 345
14. ANS: C PTS: 1 REF: 348
15. ANS: B PTS: 1 REF: 348
16. ANS: D PTS: 1 REF: 348
17. ANS: A PTS: 1 REF: 349
18. ANS: B PTS: 1 REF: 350
19. ANS: A PTS: 1 REF: 350
20. ANS: D PTS: 1 REF: 351
21. ANS: C PTS: 1 REF: 351
22. ANS: A PTS: 1 REF: 351
23. ANS: C PTS: 1 REF: 351
24. ANS: D PTS: 1 REF: 352
25. ANS: B PTS: 1 REF: 353
26. ANS: C PTS: 1 REF: 354
COMPLETION
27. ANS: Ethernet
PTS: 1 REF: 338
28. ANS: transmission time
PTS: 1 REF: 340
29. ANS: half-duplex

6. PTS: 1 REF: 343
30. ANS:
full-duplex
duplex
PTS: 1 REF: 343
31. ANS:
content-addressable memory (CAM)
content-addressable memory
CAM
PTS: 1 REF: 348
MATCHING
32. ANS: E PTS: 1 REF: 341
33. ANS: I PTS: 1 REF: 352
34. ANS: G PTS: 1 REF: 348
35. ANS: B PTS: 1 REF: 339
36. ANS: F PTS: 1 REF: 344
37. ANS: C PTS: 1 REF: 340
38. ANS: H PTS: 1 REF: 351
39. ANS: D PTS: 1 REF: 340
40. ANS: A PTS: 1 REF: 338
SHORT ANSWER
41. ANS:
Even though stations must listen to the wire before sending a transmission, two stations could listen to the
wire simultaneously and not sense a carrier signal. In such a case, both stations might begin to transmit their
data simultaneously. Shortly after the simultaneous transmissions, a collision would occur on the network
wire. The stations would detect the collision as their transmitted signals collided with one another.
Once a collision is detected, the first station to detect the collision transmits a 32-bit jam signal that tells all
other stations not to transmit for a brief period (9.6 microseconds or slightly more). The jam signal is used to
ensure that all stations are aware that a collision has occurred. After the jam signal is transmitted, the two sta-
tions that caused the collision use an algorithm to enter a backoff period, which causes them not to transmit
for a random interval. The backoff period is an attempt to ensure that the two stations do not immediately
cause another collision.
PTS: 1 REF: 338
42. ANS:

7. One simple way to reduce broadcast traffic is to reduce the number of services that servers provide on your
network and to limit the number of protocols in use on your network. Limiting the number of services will
help because each computer that provides a service, such as file sharing, broadcasts its service at a periodic
interval over each protocol it has configured. Many operating systems allow you to bind the service selective-
ly to only a specific protocol, which will reduce broadcast traffic on the network. You can also eliminate un-
necessary protocols to eliminate broadcast traffic on the network. An example of an unnecessary protocol is
the IPX protocol on a server in an IP-only network. In this case, services would be advertised on both IP and
IPX, when other stations would only be communicating via IP. IPX advertisements and the use of the IPX
protocol is unnecessary in this case because no other stations on the network would be using IPX.
PTS: 1 REF: 339
43. ANS:
An Ethernet packet sent between two stations should be between 64 bytes and 1518 bytes. According to Eth-
ernet specifications, shorter or longer frames are errors. Frame size errors that occur on Ethernet networks in-
clude:
• Short frame or runt—A frame that is shorter than 64 bytes. A collision, a faulty network adapter, corrupt
NIC software drivers, or a repeater fault can cause this error.
• Long frame or giant—A frame that is larger than 1518 bytes. Because 1518 is the largest legal frame size, a
long frame is too large to be valid. A collision, faulty network adapter, illegal hardware configuration,
transceiver or cable fault, termination problem, corrupt NIC software drivers, repeater fault, or noise can
cause this error.
• Jabber—This is another classification for giant or long frames. This frame is longer than Ethernet standards
allow (1518 bytes) and has an incorrect frame check sequence (FCS).
PTS: 1 REF: 341
44. ANS:
Fast Ethernet, which is defined under the IEEE 802.3u standard, has three defined implementations:
• 100Base-TX—Uses two pairs of either Category 5 unshielded twisted-pair (UTP) or shielded twisted-pair
(STP); one pair is used for transmit (TX), and the other is used for receive (RX). The maximum segment
length is 100 meters; two Class II repeaters and a five-meter patch cable can be used to create a maximum
distance of 205 meters between stations for each collision domain.
• 100Base-T4—Uses four pairs of either Category 3, 4, or 5 UTP cable; one pair is used for TX, one pair for
RX, and two pairs are used as bidirectional data pairs. The maximum segment length is 100 meters; as with
100Base-TX, two Class II repeaters and a five-meter patch cable can be used to create a maximum distance of
205 meters between stations for each collision domain. Because all four pairs are used, the T4 specification
does not support full-duplexing, which is discussed in the next section.
• 100Base-FX—Uses multimode fiber-optic (MMF) cable with one TX and one RX strand per link. The max-
imum segment length is 412 meters.
PTS: 1 REF: 342
45. ANS:
The Gigabit Ethernet specifications and the governing IEEE standards are:
• 1000Base-TX (802.3ab)—Uses four pairs of Category 5 unshielded twisted-pair cable. The maximum seg-
ment length is 100 meters.
• 1000Base-SX (802.3z)—Uses multimode fiber. The maximum segment length varies based on what type of
fiber is being used. For example, using a 62.5 micron core, the maximum length is 220 meters. When using a
50 micron core, the maximum length is 550 meters.
• 1000Base-LX (802.3z)—Uses single-mode fiber. The maximum distance for this standard is 10 kilometers.
• 1000Base-CX (802.3z)—Uses shielded twisted-pair copper cabling. The maximum segment length is 25 me-
ters.

8. PTS: 1 REF: 343
46. ANS:
The benefits of using full-duplex are:
• Time is not wasted retransmitting frames because collisions do not occur.
• The full bandwidth is available in both directions because the send and receive functions are separate.
• Stations do not have to wait until other stations complete their transmissions because only one transmitter is
used for each twisted pair.
PTS: 1 REF: 344
47. ANS:
Switches provide the following benefits:
• Reduction in network traffic and collisions
• Increase in available bandwidth per station, because stations can communicate in parallel
• Increase in the effective distance of a LAN by dividing it into multiple collision domains
• Increased security, because unicast traffic is sent directly to its destination and not to all other stations on the
collision domain
PTS: 1 REF: 347
48. ANS:
Switches that use cut-through forwarding start sending a frame immediately after reading the destination
MAC address into their buffers. The main benefit of cut-through forwarding is a reduction in latency, because
the forwarding decision is made almost immediately after the frame is received. For example, the switching
decision is made after receiving 14 bytes of a standard Ethernet frame.
The drawback to forwarding the frame immediately is the potential for errors in the frame that the switch
would be unable to detect because the switch only reads a small portion of the frame into its buffer. Of course,
any errors that occur in the preamble, start frame delimiter (SFD), or destination address fields will not be
propagated by the switch, unless they are corrupted in such a way as to appear valid, which is highly unlikely.
PTS: 1 REF: 349-350
49. ANS:
The actual task of setting the host name on the Cisco Catalyst switch is identical to setting the host name on a
Cisco router. As with the router, the host name is only locally significant—that is, the function of the name is
to identify the switch, not to provide any sort of Internet name resolution. It is best to select a name that clear-
ly identifies the location of the switch. For example, if you worked for a company named HudLogic, Inc. and
its switch was on the fourth floor of Room 410, you might name the switch Rm410HL. To configure this
name, you would type:
Switch(config)#hostname Rm410HL
Once the host name is set, the prompt will change to reflect the name of the switch. Continuing our example,
the prompt would change to:
Rm410HL(config)#
PTS: 1 REF: 352
50. ANS:

9. The violation command dictates what happens when a switch encounters a violation of the configured
switchport security. The default is to shut down the interface. You can also define the action with one of the
following three options: protect, restrict, and shutdown. The protect option stops forwarding of
traffic from any host that connects after the maximum number of MAC addresses has been learned. In our ex-
ample, the maximum number of MAC addresses is 10. If the protect option was selected, the 11th address
and any subsequent new MAC addresses on the port would be prevented from communicating. The restrict
option also stops all traffic above the number of defined MAC addresses. In addition, it sends an alert that a
security violation has occurred. The final option, shutdown, shuts the port down if a security violation oc-
curs.
PTS: 1 REF: 354