Network+ Guide to Networks, Chapter 6 Review
Network Hardware, Switching, and, Routing.
Chapter Summary
■ Network adapters come in a
variety of types depending on access method (Ethernet), network transmission
speed (for example, 100 Mbps versus 1 Gbps), connector interfaces (for example,
SC versus RJ-45), number of ports, type of compatible motherboard or device,
and manufacturer.
■ Newer computers may come with
PCIe expansion board NICs, which attach to the motherboard via an expansion
slot, or on-board NICs (especially in the case of laptops), which are
integrated into the motherboard. Peripheral NICs, such as those that connect
via USB port, can also be used.
■ NICs are designed to be used
with either wire-bound or wireless connections. A wireless NIC uses an antenna
to exchange signals with the network. This type of connectivity suits
environments in which cabling cannot be installed or where roaming clients must
be supported.
■ Modular interfaces such as GBICs
(Gigabit interface converters) and SFP (small formfactor pluggable)
transceivers enable network administrators to add and remove network
connections to and from connectivity devices without negatively affecting operations.
■ Repeaters are the connectivity
devices that perform the regeneration of a digital signal. They belong to the
Physical layer of the OSI model; therefore, they do not have any means to
interpret the data they are retransmitting.
■ At its most primitive, a hub is
a multiport repeater. A hub contains multiple data ports into which the patch
cables for network nodes are connected. The hub accepts signals from a
transmitting node and repeats those signals to all other connected nodes in a
broadcast fashion, thereby creating a single collision domain. Most hubs also
contain one port, called an uplink port, which allows the hub to connect to another
hub or other connectivity device.
■ Bridges resemble repeaters in
that they have a single input and a single output port, but they can interpret
the data they retransmit. Bridging occurs at the Data Link layer of the OSI
model. Bridges read the destination’s MAC address information and decide whether
to forward (retransmit) a packet to another segment on the network or, if the destination
address belongs to the same segment as the source address, discard it.
■ As nodes transmit data through
the bridge, the bridge establishes a filtering database of known MAC addresses
and their locations on the network. The bridge uses its filtering database to
determine whether a packet should be forwarded or filtered.
■ Switches subdivide a network
into smaller, logical pieces. They operate at the Data Link layer (Layer 2) of
the OSI model and can interpret MAC address information. In this respect,
switches resemble bridges.
■ Switches are generally secure
because they isolate one device’s traffic from other devices’ traffic.
Because switches provide separate channels for potentially every device, they allow
applications that transfer a large amount of traffic and that are sensitive to
time delays, such as videoconferencing, to make full use of the network’s capacity.
■ A switch running in cut-through
mode reads a frame’s header and decides where to forward the data before it
receives the entire packet. In store-and-forward mode, switches read the entire
data frame into their memory and check it for accuracy before transmitting it.
Although this method is more time consuming than the cut-through method, it
allows store-and-forward switches to transmit data more accurately.
■ Switches can create VLANs
(virtual local area networks) by logically grouping several ports into a
broadcast domain. The ports do not have to reside on the same switch or even on
the same network segment. VLANs can isolate nodes and their traffic for security,
easier management, or better performance. Multiple VLANs can be carried over
single switch interfaces using VLAN trunking.
■ On networks with several
interconnected switches, STP (Spanning Tree Protocol) prevents traffic loops
(and, as a consequence, broadcast storms) by calculating paths that avoid potential
loops and by artificially blocking the links that would complete a loop.
■ Manufacturers are producing
switches that can operate at Layer 3 (Network layer) and Layer 4 (Transport
layer) of the OSI model, making them act more like routers. The ability to
interpret higher-layer data enables switches to perform advanced filtering,
statistics keeping, and security functions.
■ A router is a multiport device
that can connect dissimilar LANs and WANs running at different transmission
speeds, using a variety of protocols. Routers interpret logical addresses and
determine the best path between nodes. They operate at the Network layer (Layer
3) or higher of the OSI model.
■ Static routing is a technique in
which a network administrator programs a router to use specific paths between
nodes. Dynamic routing automatically calculates the best path between two nodes
and accumulates this information in a routing table. If congestion or failures
affect the network, a router using dynamic routing can detect the problems and
reroute data through a different path. Most modern networks use dynamic
routing.
■ To determine the best path,
routers communicate with each other through routing protocols. Different
routing protocols use different routing metrics to choose the best path.
■ Routing metrics may factor in
the number of hops between nodes, throughput, delay, MTU, cost, load, and
reliability.
■ Distance-vector routing
protocols determine the best route for data based on the distance to a
destination. Some distance-vector routing protocols only factor in the number
of hops to the destination, while others take into account latency and other network
traffic characteristics.
■ A link-state routing protocol
enables routers across a network to share information, after which each router
can independently map the network and determine the best path between itself
and a packet’s destination node.
■ Some routing protocols reflect
characteristics of both link-state and distance-vector routing protocols and
are known as hybrid routing protocols.
■ RIP (Routing Information
Protocol), a distance-vector routing protocol, is the slowest and least secure
and limits transmissions to 15 hops. RIPv2 makes up for some of the original
RIP’s overhead and security limitations, but its forwarding remains limited to 15
hops. RIP belongs to the IGP (Interior Gateway Protocol) category of protocols that
can forward data only within an autonomous LAN.
■ BGP (Border Gateway Protocol), used primarily for
routing over Internet backbones, uses the most complex best-path calculation of
all the commonly used routing protocols. It’s considered a border routing
protocol.
■ OSPF (Open Shortest Path First)
is a link-state routing protocol used on interior or border routers. It was
introduced as an improvement to RIP and can coexist with RIP (or RIPv2) on a
network. Unlike RIP, OSPF imposes no hop limits on a transmission path. Also,
OSPF uses a more complex algorithm for determining best paths than RIP uses.
■ IS-IS uses virtually the same
methods as OSPF to calculate best paths, is less common, and is limited to
interior routers.
■ EIGRP (Enhanced Interior Gateway
Routing Protocol) is a hybrid EGP type of routing protocol and is a Cisco
standard commonly used on LANs that use exclusively Cisco routers.
■ Gateways are combinations of
networking hardware and software that connect two dissimilar kinds of networks.
Specifically, they may connect two systems that use different formatting,
communications protocols, or architecture. To accomplish this task, they must
operate at multiple layers of the OSI model.
■ Several different network
devices can perform functions at multiple layers of the OSI model, including
e-mail gateways, Internet gateways, LAN gateways, firewalls, and voice/data
gateways.
Key Terms
802.1D - The IEEE
standard that describes, among other things, bridging and STP (Spanning Tree
Protocol).
802.1q - The IEEE
standard that specifies how VLAN and trunking information appear in frames and
how switches and bridges interpret that information.
802.1w - The IEEE
standard that describes RSTP (Rapid Spanning Tree Protocol), which evolved from
STP (Spanning Tree Protocol).
access port - The
interface on a switch used for an end node. Devices connected to access ports
are unaware of VLAN information.
application switch A - switch
that provides functions between Layer 4 and Layer 7 of the OSI model.
backplane - A synonym
for motherboard, often used in the context of switches and routers.
best path - The most
efficient route from one node on a network to another. Under optimal network
conditions, the best path is the most direct path between two points. However, when
traffic congestion, segment failures, and other factors create obstacles, the
most direct path might not be the best path.
BGP (Border Gateway Protocol) - A distance-vector routing protocol capable of
considering many factors in its routing metrics. BGP, an Exterior Gateway
Protocol, is the routing protocol used on Internet backbones.
BID (Bridge ID) - A
combination of a 2-byte priority field and a bridge’s MAC address, used in STP
(Spanning Tree Protocol) to select a root bridge.
Border Gateway Protocol - See BGP.
border router - A router
that connects an autonomous LAN with an exterior network—for example, the
router that connects a business to its ISP. bridge A connectivity device that
operates at the Data Link layer (Layer 2) of the OSI model and reads header
information to forward packets according to their MAC addresses. Bridges use a
filtering database to determine which packets to discard and which to forward.
Bridges contain one input and one output port and separate network segments.
Bridge ID - See BID.
bus - The type of circuit used by a
computer’s motherboard to transmit data to components. Most new Pentium
computers use buses capable of exchanging 32 or 64 bits of data. As the number
of bits of data a bus handles increases, so too does the speed of the device
attached to the bus.
content switch - A switch
that provides functions between Layer 4 and Layer 7 of the OSI model.
convergence time - The time it
takes for a router to recognize a best path in the event of a change or network
outage.
cost - In the context of routing
metrics, the value assigned to a particular route as judged by the network
administrator. The more desirable the path, the lower its cost.
cut-through mode - A
switching mode in which a switch reads a frame’s header and decides where to
forward the data before it receives the entire packet. Cut-through mode is
faster, but less accurate, than the other switching method, store-and-forward
mode.
device driver - The
software that enables an attached device to communicate with the computer’s
operating system.
distance-vector - The
simplest type of routing protocols, these determine the best route for data
based on the distance to a destination. Some distance-vector routing protocols,
like RIP, only factor in the number of hops to the destination, while others
take into account latency and other network traffic characteristics.
driver - See device
driver.
dynamic routing - A method of
routing that automatically calculates the best path between two nodes and
accumulates this information in a routing table. If congestion or failures affect
the network, a router using dynamic routing can detect the problems and reroute
data through a different path. Modern networks primarily use dynamic routing.
EGP (Exterior Gateway Protocol) - A routing protocol that can span multiple, autonomous networks.
BGP and EIGRP are examples of Exterior Gateway Protocols.
EIGRP (Enhanced Interior Gateway Routing Protocol) - A routing protocol developed in the mid-1980s by Cisco
Systems that has a fast convergence time and a low network overhead, but is
easier to configure and less CPU-intensive than OSPF. EIGRP also offers the
benefits of supporting multiple protocols and limiting unnecessary network
traffic between routers.
Enhanced Interior Gateway Routing Protocol - See EIGRP.
ethtool - A popular
tool for viewing and modifying network interface properties on Linux computers.
expansion board - A circuit
board used to connect a device to a computer’s motherboard.
expansion card - See
expansion board.
expansion slot - A
receptacle on a computer’s motherboard that contains multiple electrical contacts
into which an expansion board can be inserted.
Exterior Gateway Protocol - See EGP.
exterior router - A router
that directs data between nodes outside a given autonomous LAN, for example,
routers used on the Internet’s backbone.
filtering database - A
collection of data created and used by a bridge that correlates the MAC
addresses of connected workstations with their locations. A filtering database
is also known as a forwarding table.
firewall - A device
(either a router or a computer running special software) that selectively filters
or blocks traffic between networks. Firewalls are commonly used to improve data
security.
forwarding table - See
filtering database.
gateway - A
combination of networking hardware and software that connects two dissimilar
kinds of networks. Gateways perform connectivity, session management, and data translation,
so they must operate at multiple layers of the OSI model.
gateway router - See border
router.
GBIC (Gigabit interface converter) - A standard type of modular interface designed in the 1990s
for Gigabit Ethernet connections. GBICs may contain RJ-45 or fiber-optic cable ports
(such as LC, SC, or ST). They are inserted into a socket on a connectivity
device’s backplane.
Gigabit interface converter - See GBIC.
hot-swappable - The feature
of a component that allows it to be installed or removed without disrupting
operations.
hub - A connectivity device that
retransmits incoming data signals to its multiple ports. Typically, hubs
contain one uplink port, which is used to connect to a network’s backbone.
IGP (Interior Gateway Protocol) - A routing protocol, such as RIP, that can only route
data within an autonomous (internal) network.
interior router - A router
that directs data between nodes on an autonomous LAN.
Intermediate System to Intermediate System - See IS-IS.
Interior Gateway Protocol - See IGP.
IS-IS (Intermediate System to Intermediate System) - A link-state routing protocol that uses a best-path
algorithm similar to OSPF’s. IS-IS was originally codified by ISO, which
referred to routers as “intermediate systems,” thus the protocol’s name. Unlike
OSPF, IS-IS is designed for use on interior routers only.
Layer 3 switch - A switch capable
of interpreting data at Layer 3 (Network layer) of the OSI model.
Layer 4 switch - A switch
capable of interpreting data at Layer 4 (Transport layer) of the OSI model.
link-state - A type of
routing protocol that enables routers across a network to share information,
after which each router can independently map the network and determine the best
path between itself and a packet’s destination node.
loopback adapter - See
loopback plug.
loopback plug - A connector
used for troubleshooting that plugs into a port (for example, a serial,
parallel, or RJ-45 port) and crosses over the transmit line to the receive
line, allowing outgoing signals to be redirected back into the computer for
testing.
main bus - See bus.
mini GBIC - See SFP.
on-board NIC - A NIC that
is integrated into a computer’s motherboard, rather than connected via an
expansion slot or peripheral bus.
on-board port - A port that
is integrated into a computer’s motherboard.
Open Shortest Path First - See OSPF.
OSPF (Open Shortest Path First) - A routing protocol that makes up for some of the limitations
of RIP and can coexist with RIP on a network.
PCIe (PCI Component Interconnect Express) - A 32-bit bus standard capable of transferring data at up
to 1 Gbps per data path, or lane, in full-duplex transmission. PCIe is commonly
used for expansion board NICs.
PCI Component Interconnect Express - See PCIe.
Rapid Spanning Tree Protocol - See RSTP.
RIP (Routing Information Protocol) - The oldest routing protocol that is still widely used, RIP
is a distance-vector protocol that uses hop count as its routing metric and
allows up to only 15 hops. It is considered an IGP. Compared with other, more
modern, routing protocols, RIP is slower and less secure.
RIPv2 (Routing Information Protocol version 2) - An updated version of the original RIP routing protocol,
which makes up for some of its predecessor’s overhead and security flaws. However,
RIPv2’s packet forwarding is still limited to a maximum 15 hops.
root bridge - The single
bridge on a network selected by the Spanning Tree Protocol to provide the basis
for all subsequent path calculations.
router - A multiport
device that operates at Layer 3 of the OSI model and uses logical addressing information
to direct data between networks or segments. Routers can connect dissimilar
LANs and WANs running at different transmission speeds and using a variety of Network
layer protocols. They determine the best path between nodes based on traffic congestion,
available versus unavailable routes, load balancing targets, and other factors.
Routing Information Protocol - See RIP.
Routing Information Protocol version 2 - See RIPv2.
routing metric - The method
used by routing protocols to determine the best path for data to follow over a
network. Routing metrics may be calculated using any of several variables, including
number of hops, bandwidth, delay, MTU, cost, and load.
routing protocols - The means
by which routers communicate with each other about network status. Routing
protocols determine the best path for data to take between nodes.
routing switch - See Layer 3
switch.
routing table - A database
stored in a router’s memory that maintains information about the location of
hosts and best paths for forwarding packets to them.
RSTP (Rapid Spanning Tree Protocol) - As described in IEEE’s 802.1w standard, a version of the
Spanning Tree Protocol that can detect and correct for network changes much
more quickly.
runt - An erroneously shortened packet.
SFP (small form-factor pluggable) transceiver - A standard hot-swappable network interface used to link
a connectivity device’s backplane with fiber-optic or copper cabling. SFPs are
known as mini GBICs because they perform a similar function as GBICs, but have
a smaller profile. Current SFP standards enable them to send and receive data
at up to 10 Gbps.
SFP GBIC - See SFP.
Spanning Tree Protocol - See STP.
static routing - A technique
in which a network administrator programs a router to use specific paths
between nodes. Because it does not account for occasional network congestion,
failed connections, or device moves and requires manual configuration, static routing
is not optimal.
store-and-forward mode- A method of switching in which a switch reads
the entire data frame into its memory and checks it for accuracy before
transmitting it. Although this method is more time consuming than the
cut-through method, it allows store-and-forward switches to transmit data more
accurately.
STP (Spanning Tree Protocol) - A switching protocol defined in IEEE 802.1D. STP operates
in the Data Link layer to prevent traffic loops by calculating paths that avoid
potential loops and by artificially blocking links that would complete a loop.
Given changes to a network’s links or devices, STP recalculates its paths.
switch - A connectivity
device that logically subdivides a network into smaller, individual collision
domains. A switch operates at the Data Link layer of the OSI model and can interpret
MAC address information to determine whether to filter (discard) or forward packets
it receives.
system bus - See bus.
trunk port - The
interface on a switch capable of managing traffic from multiple VLANs.
trunking - The
aggregation of multiple logical connections in one physical connection between
connectivity devices. In the case of VLANs, a trunk allows two switches to
manage and exchange data between multiple VLANs.
uplink port - A port on a
connectivity device, such as a hub or switch, used to connect it to another
connectivity device.
virtual local area network - See VLAN.
VLAN (virtual local area network) - A network within a network that is logically defined by grouping
its devices’ switch ports in the same broadcast domain. A VLAN can consist of any
type of network node in any geographic location and can incorporate nodes
connected to different switches.
VLAN trunking protocol - See VTP.
VTP (VLAN trunking protocol) - Cisco’s protocol for exchanging VLAN information over trunks.
VTP allows one switch on a network to centrally manage all VLANs.
Review Questions
1. Which of the following utilities
could you use to
force the NIC on your Linux server to use
full-duplex transmission?
a. ipconfig
b. ifconfig
c. iftool
d. ethtool
2. Which of the following is
a significant advantage to
using an SFP interface on
a router rather than an
on-board
NIC?
a. The SFP will be capable of
higher throughputs.
b. The SFP can be added or removed without affecting
operations,
thus allowing
for
customization and future upgrades.
c. The SFP can accept
multiple types of connectors, allowing the router
to connect two disparate network
types.
d.
The SFP promises greater
security, as it can encrypt and decrypt
data.
3. You and a friend decide to
set up Fast Ethernet networks in your respective houses
to connect a half-dozen computers
at each location.
Both of you will connect your networks
to high-speed Internet connections.
As the connectivity
device for end nodes, you purchase a router, whereas your friend uses an
old, but functional, 12-port hub he found at
a garage sale. Which
of the following will your
network
do that your friend’s
network won’t
do?
a.
Filter traffic based on IP address.
b. Transmit data
from any one of
the connected computers
to any other.
c. Create a VLAN out
of some of the computers to isolate their
transmissions and prevent
them from
affecting other connections.
d. Allow other
connectivity devices
to be added to the network
in the future.
4. You are a network
technician working on
a 100Base-T network. A
coworker has
been having trouble logging on to the server
and
asks whether you can quickly tell her if her workstation’s NIC is operating properly.
You do not have the NIC’s utility disk on
hand, but you look at the back of her
workstation and learn that although
the NIC
is properly installed and connected to the network, something’s wrong with
it. What might you
have seen
that causes you
to come to this conclusion?
a. Its activity LED is blinking green.
b. Its
loopback plug is improperly terminated.
c. It
has two types of receptacles—SC and
RJ-45—and the wrong one is in
use.
d. None of its LEDs are lit.
5. How do
bridges
keep
track
of whether they should forward or filter frames?
a. From
each frame they receive, they extract
source addresses; those frames whose
source addresses don’t belong to the bridge’s broadcast domain are
filtered.
b. They hold each frame until
it is
requested by the destination
node, at which time the bridge forwards the
data to the correct
segment
based on its
MAC address.
c.
They maintain a filtering database
that
identifies which frames can be filtered and which
should be forwarded,
based on their destination
MAC
address.
d. They compare the
incoming frame’s network
address to known addresses on both segments and filter those
that don’t belong to either.
`
6. Which of the following distinguishes
switches from repeating devices, such
as hubs?
a.
Switches
separate collision domains.
b. Switches separate
broadcast domains.
c. Switches can
alert
the network administrator to high
data collision rates.
d. Switches do not
examine Network
layer protocol information, which makes them faster
than repeating devices.
7.
In cut-through
switching, which
frame field
does the switch never read?
a. Start frame
delimiter
b. Source address
c.
Frame check sequence
d. Protocol type
8.
What potential problem does STP (Spanning Tree Protocol) address?
a. An excess of erroneously short
packets
b. A broadcast storm
c. Network congestion due to
a router failure
d. Slow
convergence time
9. You are asked to configure a backbone switch that connects
servers
supplying oceanic and atmospheric data
to mariners and pilots
around the world. Your network’s traffic
load is very high at
all times, day and night. What type of switching do you configure the switch
to use?
a. Bypass switching
b. Store-and-forward switching
c. Cut-through
switching
d. Message switching
10. Suppose your company’s network contains two separate VLANs.
Computer A is on the Customer
Service VLAN and
Computer B is
on the Warehouse VLAN.
Besides
a Layer 2 switch, what
device is required for Computer
A and Computer B to
exchange data?
a. Repeater
b. Bridge
c. Multiplexer
d. Router
11. In
STP, what device acts
as a guide to setting the best
paths between switches?
a.
Root bridge
b. Workgroup bridge
c. Parent
bridge
d. Link
bridge
12. What switching technique allows you
to funnel traffic belonging to
more
than one VLAN through
a single switch interface?
a. Jamming
b. Route capturing
c.
Trunking
d. Multiplexing
13. Which
of the following identifies the VLAN to
which each piece of data
belongs?
a. A shim added
to each packet’s
header
b. An envelope that encapsulates each
packet
c.
A tag
added to each frame’s
header
d. A FCS added to each packet’s header
14. Which
of the following routing protocols is
used on the Internet’s backbone?
a. EIGRP
b. OSPF
c. BGP
d. RIP
15. Which
of the following types of
routing protocols allows routers to exchange
information about best paths with their neighboring routers only?
a. Link-state
b. Hybrid
c.
Distance-vector
d. All of the
above
16. Why is
a large, busy network
more likely to
use dynamic routing?
a. Because dynamic routing is
the default option on most routers, and it is difficult
to
configure routers to use static routing.
b. Because dynamic routing
is the only routing method compatible with
the
BGP routing protocol, which
is necessary for routing between
WANs.
c. Because dynamic routing
allows for stricter IP filtering
and, therefore,
offers greater data
security than
static routing.
d. Because dynamic routing
automatically
selects the most
efficient
route
between nodes, reducing the possibility for human error.
17. A packet on a network using the RIP routing method has been passed from one connectivity device
to another 15 times. What
happens when it gets
passed to one more device?
a. It is returned to the node that
originally transmitted it.
b. It
is encapsulated by the routing protocol and
retransmitted.
c. It
is forwarded
to its destination by the last
device.
d. It is
discarded.
18. Which of the following factors
is not considered when
OSPF
determines the best path
for a packet?
a. Link failure
b. Number of hops
c. Throughput
d. Latency
19. What is a router’s convergence time?
a. The
time a router takes to
interpret Layer
2 addressing information
for any given
frame.
b. The maximum
amount of time a router is allowed for choosing the
best path
c. The time it
takes for a router to recognize a best
path in the event
of a change or network outage
d. The time
it takes for
border routers to exchange routing table information
20. At which layers
of the OSI model
are gateways capable of
functioning?
a. Layers 1 and 2
b. Layers 2 and 3
c. Layers
1, 2, and 3
d. At all layers
Sample Quiz
1. Which
statement is true with regard to routers?
a. A router is a very inflexible device.
b. Routers connect dissimilar networks.
c. A router must
connect to a switch to monitor network traffic and report statistics.
d. If a primary path is down, a router cancels the
transmission.
2. A
________ is a multiport connectivity device that directs data between nodes on
a network.
a. gateway
b. switch
c. NIC
d. router
3. A device
driver is software that enables an attached device to communicate with the
computer's operating system.
a. True
b. False
4. In
________ mode, a switch reads the entire data frame into its memory and checks
it for accuracy before transmitting the information.
a.
store-and-forward
b. cut-through
c. autonomous
d. fragment free
5. Routers
can create VLANs within networks by grouping a number of ports into a broadcast
domain.
a. True
b. False
6. ________
are the simplest type of connectivity devices that regenerate a digital signal.
a. Bridges
b. Repeaters
c. Gateways
d. Firewalls
7. Routers
using RIP broadcast their routing tables every 30 seconds to other routers, but
only if the tables have changed.
a. True
b. False
8. In broad
terms, ________ are combinations of networking hardware and software that
connect two dissimilar kinds of networks.
a. gateways
b. switches
c. routers
d. NICs
9. By far,
the most popular expansion board NIC today is one that uses a PCI bus.
a. True
b. False
10. A server
may act as a LAN gateway.
a. True
b. False
11. Which
statement is true with regard to switches?
a. Switches handle continuous, heavy traffic very
efficiently.
b. All switches operate at the Data Link layer of the OSI
model.
c. Each port on a
switch acts like a bridge.
d. Backbone routers provide better security and better
performance over switches.
12. Which
NIC attaches to the computer using an external PCMCIA slot?
a. Onboard
b. Peripheral
c. Expansion board
d. USB
13. ________
are devices that connect two network segments by analyzing incoming frames and
making decisions about where to direct them based on each frame's MAC address.
a. Routers
b. Gateways
c. Bridges
d. Switches
14. ________
are connectivity devices that subdivide a network into smaller logical pieces,
or segments.
a. Gateways
b. Routers
c. Switches
d. Hubs
15. Which
modular interface has made the GBIC largely obsolete?
a. RJ-45
b. PCI
c. PCIe
d. SFP
