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What OSI physical layer term describes the capacity at which a medium can carry data?
bandwidth
IEEE
EIA/TIA
air
what is
bandwidth
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1.4.2 Physical Layer Characteristics
What OSI physical layer term describes the process by which one wave modifies another wave?
modulation
IEEE
EIA/TIA
air
what is
modulation
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1.4.2 Physical Layer Characteristics
What makes fiber preferable to copper cabling for interconnecting buildings? (Choose three.)
greater distances per cable run
lower installation cost
limited susceptibility to EMI/RFI
durable connections
greater bandwidth potential
easily terminated
what is
greater distances per cable run
&
limited susceptibility to EMI/RFI
&
greater bandwidth potential
Optical fiber cable transmits data over longer distances and at higher bandwidths than any other networking media. Unlike copper wires, fiber-optic cable can transmit signals with less attenuation and is completely immune to EMI and RFI.
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1.4.5 Fiber-Optic Cabling
What does the term "attenuation" mean in data communication?
loss of signal strength as distance increases
time for a signal to reach its destination
leakage of signals from one cable pair to another
strengthening of a signal by a networking device
what is
loss of signal strength as distance increases
Data is transmitted on copper cables as electrical pulses. A detector in the network interface of a destination device must receive a signal that can be successfully decoded to match the signal sent. However, the farther the signal travels, the more it deteriorates. This is referred to as signal attenuation.
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1.4.3 Copper Cabling
What OSI physical layer term describes the measure of the transfer of bits across a medium over a given period of time?
throughput
bandwidth
latency
goodput
what is
throughput
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Blank is an always-on, high bandwidth connection that runs over telephone lines.
DSL
dialup telephone
cable
what is
DSL
Cable uses the same coaxial cable that carries television signals into the home to provide Internet access. Dialup telephone is much slower than either DSL or cable, but is the least expensive option for home users because it can use any telephone line and a simple modem.
What two criteria are used to help select a network medium from various network media? (Choose two.)
the types of data that need to be prioritized
the cost of the end devices utilized in the network
the distance the selected medium can successfully carry a signal
the number of intermediate devices installed in the network
the environment where the selected medium is to be installed
what is
the distance the selected medium can successfully carry a signal
&
the environment where the selected medium is to be installed
Criteria for choosing a network medium are the distance the selected medium can successfully carry a signal, the environment in which the selected medium is to be installed, the amount of data and the speed at which the data must be transmitted, and the cost of the medium and its installation.
Which frame forwarding method receives the entire frame and performs a cyclic redundancy check (CRC) check to detect errors before forwarding the frame?
cut-through switching
store-and-forward switching
fragment-free switching
fast-forward switching
what is
store-and-forward switching
cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data.
Fast-forward and fragment-free switching are variations of cut-through switching, which begins to forward the frame before the entire frame is received.
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1.7.4 Switch Speeds and Forwarding Methods
What is the auto-MDIX feature?
-It enables a device to automatically configure an interface to use a straight-through or a crossover cable.
-It enables a device to automatically configure the duplex settings of a segment.
-It enables a device to automatically configure the speed of its interface.
-It enables a switch to dynamically select the forwarding method.
what is
It enables a device to automatically configure an interface to use a straight-through or a crossover cable.
The auto-MDIX feature allows the device to configure its network port according to the cable type that is used (straight-through or crossover) and the type of device that is connected to that port. When a port of a switch is configured with auto-MDIX, this switch can be connected to another switch by the use of either a straight-through cable or a crossover cable.
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1.7.4 Switch Speeds and Forwarding Methods
What is one advantage of using the cut-through switching method instead of the store-and-forward switching method?
-has a positive impact on bandwidth by dropping most of the invalid frames
-makes a fast forwarding decision based on the source MAC address of the frame
-has a lower latency appropriate for high-performance computing applications
-provides the flexibility to support any mix of Ethernet speeds
what is
has a lower latency appropriate for high-performance computing applications
Cut-through switching provides lower latency switching for high-performance computing (HPC) applications. Cut-through switching allows more invalid frames to cross the network than store-and-forward switching. The cut-through switching method can make a forwarding decision as soon as it looks up the destination MAC address of the frame.
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1.7.4 Switch Speeds and Forwarding Methods
In the show running-config command, which part of the syntax is represented by running-config ?
a keyword
the command
a variable
a prompt
what is
keyword
The first part of the syntax, show , is the command, and the second part of the syntax, running-config, is the keyword. The keyword specifies what should be displayed as the output of the show command.
A user is implementing security on a small office network. Which two actions would provide the minimum security requirements for this network? (Choose two.)
implementing a firewall
installing a wireless network
installing antivirus software
implementing an intrusion detection system
adding a dedicated intrusion prevention device
what is
implementing a firewall
&
installing antivirus software
Answers Explanation & Hints:
Technically complex security measures such as intrusion prevention and intrusion prevention systems are usually associated with business networks rather than home networks. Installing antivirus software, antimalware software, and implementing a firewall will usually be the minimum requirements for home networks. Installing a home wireless network will not improve network security, and will require further security actions to be taken.
What is the purpose of the frame check sequence (FCS) field in a frame?
to obtain the MAC address of the sending node
to verify the logical address of the sending node
to compute the cyclic redundancy check CRC header for the data field
to determine if errors occurred in the transmission and reception
what is
to determine if errors occurred in the transmission and reception
The FCS field in a frame is used to detect any errors in the transmission and receipt of a frame. This is done by comparing the CRC value within the frame against a computed CRC value of the frame. If the two values do not match, then the frame is discarded.
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1.7.1 Ethernet Frames
Which switching method uses the Cyclic redundancy check (CRC) value in a frame?
cut-through
fast-forward
fragment-free
store-and-forward
what is
fragment-free
When the store-and-forward switching method is used, the switch receives the complete frame before forwarding it on to the destination. The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit. In contrast, a cut-through switch forwards the frame once the destination Layer 2 address is read. Two types of cut-through switching methods are fast-forward and fragment-free.
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1.7.4 Switch Speeds and Forwarding Methods
Which is a multicast MAC address? (hint special value 01-00-5E)
FF-FF-FF-FF-FF-FF
5C-26-0A-4B-19-3E
01-00-5E-00-00-03
00-26-0F-4B-00-3E
what is
Multicast MAC addresses begin with the special value of 01-00-5E.
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1.7.2 Ethernet MAC Address
What is a primary role of the Physical layer in transmitting data on the network?
create the signals that represent the bits in each
frame on to the media
provide physical addressing to the devices
determine the path packets take through the network
control data access to the media
create the signals that represent the bits in each frame on to the media
The OSI physical layer provides the means to transport the bits that make up a frame across the network media. This layer accepts a complete frame from the data link layer and encodes it as a series of signals that are transmitted to the local media.
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1.4.1 Purpose of the Physical Layer
What is the auto-MDIX feature on a switch?
the automatic configuration of an interface for 10/100/1000 Mb/s operation
the automatic configuration of an interface for a straight-through or a crossover Ethernet cable connection
the automatic configuration of full-duplex operation over a single Ethernet copper or optical cable
the ability to turn a switch interface on or off accordingly if an active connection is detected
what is
the automatic configuration of an interface for a straight-through or a crossover Ethernet cable connection
The auto-MDIX enables a switch to use a crossover or a straight-through Ethernet cable to connect to a device regardless of the device on the other end of the connection.
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1.7.4 Switch Speeds and Forwarding Methods
Which switching method has the lowest level of latency?
cut-through
store-and-forward
fragment-free
fast-forward
what is
fast-forward
Fast-forward switching begins to forward a frame after reading the destination MAC address, resulting in the lowest latency. Fragment-free reads the first 64 bytes before forwarding. Store-and-forward has the highest latency because it reads the entire frame before beginning to forward it. Both fragment-free and fast-forward are types of cut-through switching.
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1.7.4 Switch Speeds and Forwarding Methods
When the store-and-forward method of switching is in use, what part of the Ethernet frame is used to perform an error check?
Cyclic redundancy check (CRC) in the trailer
source MAC address in the header
destination MAC address in the header
protocol type in the header
what is
Cyclic redundancy check (CRC)
The cyclic redundancy check (CRC) part of the trailer is used to determine if the frame has been modified during transit. If the integrity of the frame is verified, the frame is forwarded. If the integrity of the frame cannot be verified, then the frame is dropped.
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1.7.4 Switch Speeds and Forwarding Methods
Which two functions are performed at the MAC sublayer of the OSI data link layer? (Choose two.)
-Implements a trailer to detect transmission errors.
-Controls the NIC responsible for sending and receiving data on the physical medium.
-Places information in the frame that identifies which network layer protocol is being used for the frame.
-Adds Layer 2 control information to network protocol data.
-Enables IPv4 and IPv6 to utilize the same network interface and media.
what is
implements a trailer to detect transmission errors.
&
Controls the NIC responsible for sending and receiving data on the physical medium.
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1.6.1 Purpose of the Data Link Layer
A network administrator is measuring the transfer of bits across the company backbone for a mission critical financial application. The administrator notices that the network throughput appears lower than the bandwidth expected. Which three factors could influence the differences in throughput? (Choose three.)
the amount of traffic that is currently crossing the network
the sophistication of the encapsulation method applied to the data
the type of traffic that is crossing the network
the latency that is created by the number of network devices that the data is crossing
the bandwidth of the WAN connection to the Internet
the reliability of the gigabit Ethernet infrastructure of the backbone
the amount of traffic that is currently crossing the network
the type of traffic that is crossing the network
the latency that is created by the number of network devices that the data is crossing
Throughput usually does not match the specified bandwidth of physical links due to multiple factors. These factors include, the amount of traffic, type of traffic, and latency created by the network devices the data has to cross.
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4.2 Physical Layer Characteristics
A Layer 2 switch is used to switch incoming frames from a 1000BASE-T port to a port connected to a 100Base-T network. Which method of memory buffering would work best for this task?
port-based buffering
level 1 cache buffering
shared memory buffering
fixed configuration buffering
what is
shared memory buffering
With shared memory buffering, the number of frames stored in the buffer is restricted only by the of the entire memory buffer and not limited to a single port buffer. This permits larger frames to be transmitted with fewer dropped frames. This is important to asymmetric switching, which applies to this scenario, where frames are being exchanged between ports of different rates. With port-based memory buffering, frames are stored in queues that are linked to specific incoming and outgoing ports making it possible for a single frame to delay the transmission of all the frames in memory because of a busy destination port. Level 1 cache is memory used in a CPU. Fixed configuration refers to the port arrangement in switch hardware.
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1.7.4 Switch Speeds and Forwarding Methods
A network administrator is connecting two modern switches using a straight-through cable. The switches are new and have never been configured. Which three statements are correct about the final result of the connection? (Choose three.)
The link between the switches will work at the fastest speed that is supported by both switches.
-The link between switches will work as full-duplex.
-If both switches support different speeds, they will each work at their own fastest speed.
-The auto-MDIX feature will configure the interfaces eliminating the need for a crossover cable.
-The connection will not be possible unless the administrator changes the cable to a crossover cable.
-The duplex capability has to be manually configured because it cannot be negotiated.
what is
The link between the switches will work at the fastest speed that is supported by both switches.
&
The link between switches will work as full-duplex.
&
The auto-MDIX feature will configure the interfaces eliminating the need for a crossover cable.
Modern switches can negotiate to work in full-duplex mode if both switches are capable. They will negotiate to work using the fastest possible speed and the auto-MDIX feature is enabled by default, so a cable change is not needed.
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1.7.4 Switch Speeds and Forwarding Methods
Which advantage does the store-and-forward switching method have compared with the cut-through switching method?
collision detecting
frame error checking
faster frame forwarding
frame forwarding using IPv4 Layer 3 and 4 information
what is
frame error checking
A switch using the store-and-forward switching method performs an error check on an incoming frame by comparing the frame check sequence (FCS) value against its own frame check sequence (FCS) calculations after the entire frame is received. In comparison, a switch using the cut-through switching method makes quick forwarding decisions and starts the forwarding process without waiting for the entire frame to be received. Thus a switch using cut-through switching may send invalid frames to the network. The performance of store-and-forward switching is slower compared to cut-through switching performance. Collision detection is monitored by the sending device. Store-and-forward switching does not use IPv4 Layer 3 and 4 information for its forwarding decisions.
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1.7.4 Switch Speeds and Forwarding Methods
What action will occur if a switch receives a frame and does have the source MAC address in the MAC table?
-The switch refreshes the timer on that entry.
-The switch shares the MAC address table entry with any connected switches.
-The switch does not forward the frame.
-The switch sends the frame to a connected router because the destination MAC address is not local
what is
The switch refreshes the timer on that entry.
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1.7.2 Ethernet MAC Address