Chapter 2: Network Devices

TRUE/FALSE

	1.	The number of nodes on a network and the length of cable used influence the quality of communication on the network.

ANS:	T	PTS:	1	REF:	26

	2.	Repeaters and hubs reformat data structures, so they can connect networks that require different types of frames.

ANS:	F	PTS:	1	REF:	28

	3.	The IEEE standards for WLANs use unlicensed, but not unregulated, radio frequencies.

ANS:	T	PTS:	1	REF:	29

	4.	Bridges operate at the Network layer of the OSI model.

ANS:	F	PTS:	1	REF:	33

	5.	Like bridges, switches operate at the Network layer of the OSI model.

ANS:	F	PTS:	1	REF:	35

MULTIPLE CHOICE

	1.	On analog networks, devices that boost the signal are called ____.
a.	routers	c.	hubs	
b.	amplifiers	d.	repeaters	

ANS:	B	PTS:	1	REF:	26

	2.	Devices that “see” the traffic of other devices are said to be on the same ____ as those devices.
a.	ring	c.	level	
b.	block	d.	collision domain	

ANS:	D	PTS:	1	REF:	28

	3.	If a single access point is available in infrastructure mode, then the mode is said to be a(n) ____.
a.	Virtual Service Set (VSS)	c.	Basic Service Set (BSS)	
b.	Extended Service Set (ESS)	d.	Logical Service Set (LSS)	

ANS:	C	PTS:	1	REF:	30

	4.	Typically WLANs involve multiple access points connected to various switches in the network. This type of infrastructure mode is known as a(n) ____.
a.	Extended Service Set (ESS)	c.	Virtual Service Set (VSS)	
b.	Basic Service Set (BSS)	d.	Logical Service Set (LSS)	

ANS:	A	PTS:	1	REF:	30

	5.	A ____ filters traffic between network segments by examining the destination MAC address.
a.	hub	c.	router	
b.	repeater	d.	bridge	

ANS:	D	PTS:	1	REF:	33

	6.	____ increase network performance by reducing the number of frames transmitted to the rest of the network.
a.	Switches	c.	Hubs	
b.	Gateways	d.	Amplifiers	

ANS:	A	PTS:	1	REF:	35

	7.	Switches filter based on ____ addresses.
a.	logical	c.	MAC	
b.	IP	d.	TCP/IP	

ANS:	C	PTS:	1	REF:	36

	8.	____ provide filtering and network traffic control on LANs and WANs. These devices can connect multiple segments and multiple networks.
a.	Hubs	c.	Switches	
b.	Routers	d.	Bridges	

ANS:	B	PTS:	1	REF:	37

	9.	Routers operate at the ____ layer of the OSI model.
a.	Network	c.	Data Link	
b.	Transport	d.	Physical	

ANS:	A	PTS:	1	REF:	37

	10.	When TCP/IP is used on an internetwork, the logical address is known as a(n) ____ address.
a.	MAC	c.	physical	
b.	IP	d.	domain	

ANS:	B	PTS:	1	REF:	38

	11.	____ are commonly used to connect networks to the Internet.
a.	Bridges	c.	Routers	
b.	Switches	d.	Hubs	

ANS:	C	PTS:	1	REF:	39

	12.	A(n) ____ functions as both a bridge for nonroutable protocols and a router for routable protocols.
a.	switch	c.	amplifier	
b.	hub	d.	brouter	

ANS:	D	PTS:	1	REF:	39

	13.	A(n) ____ is usually a combination of hardware and software. Its purpose is to translate between different protocol suites.
a.	amplifier	c.	hub	
b.	gateway	d.	router	

ANS:	B	PTS:	1	REF:	40

	14.	____ have the most negative effect on network performance.
a.	Routers	c.	Switches	
b.	Bridges	d.	Gateways	

ANS:	D	PTS:	1	REF:	40

	15.	____ is a network access method (or media access method) originated by the University of Hawaii.
a.	FDDI	c.	Ethernet	
b.	AppleTalk	d.	Token Ring	

ANS:	C	PTS:	1	REF:	40

	16.	Ethernet uses ____ to prevent data packets from colliding on the network.
a.	CSMA/CD	c.	AppleTalk	
b.	CSMA/CA	d.	LPC	

ANS:	A	PTS:	1	REF:	40

	17.	A ____ is the physical area in which a frame collision might occur.
a.	signal domain	c.	jam domain	
b.	jam area	d.	collision domain	

ANS:	D	PTS:	1	REF:	41

	18.	____ Ethernet uses the same network access method (CSMA/CD) as common 10BaseT Ethernet, but provides 10 times the data transmission rate.
a.	Fast	c.	10 Gigabit	
b.	Gigabit	d.	Terabit	

ANS:	A	PTS:	1	REF:	41

	19.	Fast Ethernet is defined under the IEEE ____ standard.
a.	802.3b	c.	802.3u	
b.	802.3f	d.	802.3z	

ANS:	C	PTS:	1	REF:	41

	20.	In ____ communications, devices can send and receive signals, but not at the same time.
a.	full-duplex	c.	duplex	
b.	half-duplex	d.	wire-duplex	

ANS:	B	PTS:	1	REF:	41

	21.	In ____ communications, devices can send and receive signals simultaneously.
a.	full-duplex	c.	half-duplex	
b.	mutex	d.	single-duplex	

ANS:	A	PTS:	1	REF:	41

COMPLETION

	1.	____________________ usually refers to the physical layout of network cable and devices.

ANS:	Topology

PTS:	1	REF:	27

	2.	____________________ provide cell-based areas where wireless clients such as laptops and PDAs can connect to the network by associating with the access point.

ANS:	Wireless access points

PTS:	1	REF:	28

	3.	____________________ is the breaking down of a single heavily populated network segment into smaller segments, or collision domains, populated by fewer nodes.

ANS:	Segmentation

PTS:	1	REF:	32

	4.	A switch opens a(n) ____________________ between the source and the destination. This prevents communications between just two computers from being broadcast to every computer on the network or segment.

ANS:	virtual circuit

PTS:	1	REF:	36

	5.	When machines must share a wire and compete for available bandwidth with other machines, they experience ____________________.

ANS:	contention

PTS:	1	REF:	36

MATCHING

Match each item with a statement below:
a.	Attenuation	f.	Broadcast storm	
b.	Hub	g.	Microsegmentation	
c.	Service Set Identifier (SSID)	h.	Internetworks	
d.	Segment	i.	Broadcast domain	
e.	Broadcast frame	

	1.	a group of network devices that will receive LAN broadcast traffic from each other

	2.	a generic connection device used to tie several networking cables together to create a link between different stations on a network

	3.	preventing communications between just two computers from being broadcast to every computer on the network or segment

	4.	when two or more stations engage in the transmission of excessive broadcast traffic

	5.	networks connected by multiple routers

	6.	a part of a network that is divided logically or physically from the rest of the network

	7.	wireless network name

	8.	a frame destined for all computers on the network

	9.	degradation of signal clarity

	1.	ANS:	I	PTS:	1	REF:	38

	2.	ANS:	B	PTS:	1	REF:	27

	3.	ANS:	G	PTS:	1	REF:	36

	4.	ANS:	F	PTS:	1	REF:	35

	5.	ANS:	H	PTS:	1	REF:	37

	6.	ANS:	D	PTS:	1	REF:	32

	7.	ANS:	C	PTS:	1	REF:	30

	8.	ANS:	E	PTS:	1	REF:	33

	9.	ANS:	A	PTS:	1	REF:	26

SHORT ANSWER

	1.	Describe active and passive hubs.

ANS:	
A hub is a generic connection device used to tie several networking cables together to create a link between different stations on a network. Most hubs are plugged into electric power and are active hubs. They usually amplify or repeat signals that pass through them, similar to repeaters. Because they have multiple inbound and outbound connections, these hubs are also known as multiport repeaters. A hub that merely connects cables on a network and provides no signal regeneration is called a passive hub and is not a repeater.

PTS:	1	REF:	27

	2.	What are the advantages of using repeaters and hubs?

ANS:	
Advantages of using repeaters and hubs on your network:
• Repeaters and hubs can extend a network’s total distance.
• Repeaters and hubs do not seriously affect network performance.
• Certain repeaters can connect networks using different physical media.

PTS:	1	REF:	28

	3.	Briefly describe the components of a wireless network.

ANS:	
802.11 can be used in two different modes. Wireless clients can connect and communicate directly with each other in ad hoc mode. In this mode, there is no access point, which is not typical. Commonly, wireless clients attach wirelessly to an access point in infrastructure mode. As previously stated, this mode involves the access point wired back into a switch so that the client has access to the LAN and WAN, not just the WLAN.

If a single access point is available in infrastructure mode, then the mode is said to be a Basic Service Set (BSS). More typically, WLANs involve multiple access points connected to various switches in the network. This allows users to roam around the building and remain connected to the WLAN as well as the LAN and WAN. This type of infrastructure mode is known as an Extended Service Set (ESS).

PTS:	1	REF:	30

	4.	What are the steps for adding a WLAN to a LAN?

ANS:	
In general, you should follow these steps when adding a WLAN to your LAN:
1. Make sure your wired LAN is working.
2. Complete a wireless site survey to determine access point placement.
3. Install the access point(s) with no security.
4. Attempt to associate to the access point with a laptop.
5. Configure security on both the access point and the client.
6. Verify connectivity at all layers.

PTS:	1	REF:	31

	5.	Briefly describe transparent bridges.

ANS:	
Transparent bridges are also called learning bridges because they build a table of MAC addresses as they receive frames. This means that they “learn” which addresses are on which segments. When a bridge first receives power, its bridging table is empty. Over time, though, it learns which segments have which MAC addresses as frames are forwarded. The bridge uses the source MAC addresses to determine which addresses are on which segments. By determining a frame’s origin, the bridge knows where to send frames in the future. Ethernet networks mainly use transparent bridges. Token Ring networks usually employ source-routing bridges.

PTS:	1	REF:	34

	6.	What are the advantages of using a bridge?

ANS:	
The advantages of using a bridge include the following:
• Bridges can extend a network by acting as a repeater.
• Bridges can reduce network traffic on a segment by subdividing network communications.
• Bridges increase the available bandwidth to individual nodes because fewer nodes share a collision domain.
• Bridges reduce collisions.
• Some bridges connect networks using different media types and architectures.

PTS:	1	REF:	35

	7.	What are the advantages of using switches?

ANS:	
The advantages of switches include the following:
• Switches increase available network bandwidth.
• Switches reduce the workload on individual computers.
• Switches increase network performance.
• Networks that include switches experience fewer frame collisions because switches create collision domains for each connection (a process called microsegmentation).
• Switches connect directly to workstations.

PTS:	1	REF:	36-37

	8.	What are the disadvantages of using routers on the network?

ANS:	
The disadvantages of using routers on the network include the following:
• Routers work only with routable network protocols; most but not all protocols are routable.
• Routers are more expensive than other devices.
• Dynamic router communications (inter-router communication) cause additional network overhead, which results in less bandwidth for user data.
• Routers are slower than other devices because they must analyze a data transmission from the Physical through the Network layer, whereas bridges and switches only read two layers of information: the Physical and Data Link.

PTS:	1	REF:	39

	9.	Briefly describe Gigabit Ethernet.

ANS:	
Gigabit Ethernet (1000BaseX) is the next iteration of Ethernet, increasing the speed to 1000 Mbps. IEEE 802.3z includes 1000BaseSX over multimode fiber, 1000BaseLX over single-mode fiber, and 1000BaseCX over balanced-copper cabling. The IEEE 802.3ab standard defines the more common 1000BaseT configuration over all four pairs of UTP. Although Gigabit Ethernet can work in half-duplex mode through hubs, this is not typical. Almost all applications of the standard are full-duplexed through switches. 10 Gigabit Ethernet (10GBaseX, 10GbE or 10GigE) is the fastest of the Ethernet standards. This relatively new standard is ten times faster than Gigabit Ethernet. 10 Gigabit Ethernet is full-duplex only, through switches.

PTS:	1	REF:	41

	10.	What are the benefits of using full-duplex?

ANS:	
The benefits of using full-duplex are:
• Time is not wasted retransmitting frames, because there are no collisions.
• 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.

PTS:	1	REF:	42