Podcast
Questions and Answers
Which of the following is NOT a type of private WAN infrastructure?
Which of the following is NOT a type of private WAN infrastructure?
What is a distinct advantage of using dedicated point-to-point leased lines?
What is a distinct advantage of using dedicated point-to-point leased lines?
What technology is used predominantly in service provider networks for high bandwidth connections?
What technology is used predominantly in service provider networks for high bandwidth connections?
Which of the following public WAN technologies allows for broadband Internet access?
Which of the following public WAN technologies allows for broadband Internet access?
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What method is suggested for protecting data traveling over a public WAN?
What method is suggested for protecting data traveling over a public WAN?
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Which technique is associated with long-range fiber-optic communications?
Which technique is associated with long-range fiber-optic communications?
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Which of the following is a disadvantage of using public WAN infrastructure?
Which of the following is a disadvantage of using public WAN infrastructure?
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What is a characteristic of circuit-switched links?
What is a characteristic of circuit-switched links?
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What is the main technology used in Multiprotocol Label Switching (MPLS) to direct data between routers?
What is the main technology used in Multiprotocol Label Switching (MPLS) to direct data between routers?
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Which of the following technologies is commonly being replaced by Ethernet WANs?
Which of the following technologies is commonly being replaced by Ethernet WANs?
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Which of these is NOT a listed benefit of using Ethernet WAN services?
Which of these is NOT a listed benefit of using Ethernet WAN services?
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What type of media is used in the private WAN technologies discussed?
What type of media is used in the private WAN technologies discussed?
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Which of the following services is a primary technology provider for WANs?
Which of the following services is a primary technology provider for WANs?
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Which access technology can connect to the MPLS cloud, according to its capabilities?
Which access technology can connect to the MPLS cloud, according to its capabilities?
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What payload types can MPLS carry?
What payload types can MPLS carry?
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What technology is positioned as a replacement for traditional WAN technologies like Frame Relay?
What technology is positioned as a replacement for traditional WAN technologies like Frame Relay?
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What is a VPN primarily used for when accessing a corporate WAN?
What is a VPN primarily used for when accessing a corporate WAN?
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Which of the following is NOT a benefit of using a VPN?
Which of the following is NOT a benefit of using a VPN?
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What type of VPN connects entire networks, such as a branch office to a headquarters?
What type of VPN connects entire networks, such as a branch office to a headquarters?
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What is a characteristic of a remote-access VPN?
What is a characteristic of a remote-access VPN?
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Which statement is true regarding VPN tunnels?
Which statement is true regarding VPN tunnels?
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What must network administrators consider when choosing a WAN connection?
What must network administrators consider when choosing a WAN connection?
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Which term describes the connection method used by a VPN?
Which term describes the connection method used by a VPN?
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How does a VPN typically achieve security?
How does a VPN typically achieve security?
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A VPN is an unencrypted connection between private networks over a public network.
A VPN is an unencrypted connection between private networks over a public network.
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Cost savings is one of the benefits of using VPNs.
Cost savings is one of the benefits of using VPNs.
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Site-to-site VPNs connect individual users to a company network.
Site-to-site VPNs connect individual users to a company network.
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Remote-access VPNs allow telecommuters to securely access a company network over the Internet.
Remote-access VPNs allow telecommuters to securely access a company network over the Internet.
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VPN tunnels use dedicated Layer 2 connections like leased lines.
VPN tunnels use dedicated Layer 2 connections like leased lines.
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Scalability is a disadvantage of using VPNs.
Scalability is a disadvantage of using VPNs.
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VPNs are only useful for large corporations with extensive WAN needs.
VPNs are only useful for large corporations with extensive WAN needs.
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VPNs provide compatibility with broadband technology as one of their benefits.
VPNs provide compatibility with broadband technology as one of their benefits.
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ISDN Basic Rate Interface (BRI) provides two 128 kb/s bearer channels.
ISDN Basic Rate Interface (BRI) provides two 128 kb/s bearer channels.
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A Primary Rate Interface (PRI) in North America delivers 23 B channels with 64 kb/s each.
A Primary Rate Interface (PRI) in North America delivers 23 B channels with 64 kb/s each.
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ISDN technology has increased in popularity due to the rise of DSL and other broadband services.
ISDN technology has increased in popularity due to the rise of DSL and other broadband services.
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Frame Relay is a Layer 3 WAN technology used to interconnect enterprise LANs.
Frame Relay is a Layer 3 WAN technology used to interconnect enterprise LANs.
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Data rates of up to 4 Mb/s are supported by Frame Relay technology.
Data rates of up to 4 Mb/s are supported by Frame Relay technology.
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A single router can connect multiple sites using permanent virtual circuits (PVCs).
A single router can connect multiple sites using permanent virtual circuits (PVCs).
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ISDN can serve as a backup if a leased line fails.
ISDN can serve as a backup if a leased line fails.
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An edge router in Frame Relay requires multiple interfaces when using several virtual circuits.
An edge router in Frame Relay requires multiple interfaces when using several virtual circuits.
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A very small aperture terminal (VSAT) can create a private WAN using satellite communications.
A very small aperture terminal (VSAT) can create a private WAN using satellite communications.
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DSL technology uses coaxial cable to transport high-bandwidth data.
DSL technology uses coaxial cable to transport high-bandwidth data.
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Cable modems provide a connection that is only available during certain hours of the day.
Cable modems provide a connection that is only available during certain hours of the day.
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For DSL, a modem is needed to convert an Ethernet signal into a DSL signal.
For DSL, a modem is needed to convert an Ethernet signal into a DSL signal.
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Signals for VSAT travel approximately 10,000 kilometers to the satellite and back.
Signals for VSAT travel approximately 10,000 kilometers to the satellite and back.
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DSL is primarily used by IT departments to support home workers.
DSL is primarily used by IT departments to support home workers.
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A cable television provider's network can provide less bandwidth than conventional telephone lines.
A cable television provider's network can provide less bandwidth than conventional telephone lines.
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A DSLAM at the provider location is used to multiplex multiple DSL subscriber lines into a single high-capacity link.
A DSLAM at the provider location is used to multiplex multiple DSL subscriber lines into a single high-capacity link.
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A cable modem translates digital signals into broadband frequencies used for transmitting on a cable television network.
A cable modem translates digital signals into broadband frequencies used for transmitting on a cable television network.
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WiMAX technology provides coverage over distances greater than 30 miles.
WiMAX technology provides coverage over distances greater than 30 miles.
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Municipal Wi-Fi networks offer free internet access in many cities.
Municipal Wi-Fi networks offer free internet access in many cities.
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A cable modem termination system (CMTS) is unnecessary for providing Internet services to subscribers.
A cable modem termination system (CMTS) is unnecessary for providing Internet services to subscribers.
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WiMAX operates similarly to Wi-Fi but at lower speeds.
WiMAX operates similarly to Wi-Fi but at lower speeds.
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Wireless routers typically have a transmission range of less than 100 feet.
Wireless routers typically have a transmission range of less than 100 feet.
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WiMAX uses a network of wireless access points similar to Wi-Fi hotspots.
WiMAX uses a network of wireless access points similar to Wi-Fi hotspots.
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Subscribers of WiMAX must be within 30 feet of a tower to access the service.
Subscribers of WiMAX must be within 30 feet of a tower to access the service.
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Satellite Internet upload speeds are usually about one-tenth of the download speed.
Satellite Internet upload speeds are usually about one-tenth of the download speed.
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Cellular service is a type of wired WAN technology.
Cellular service is a type of wired WAN technology.
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The Long-Term Evolution (LTE) technology is part of the second generation of cellular technology.
The Long-Term Evolution (LTE) technology is part of the second generation of cellular technology.
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VSAT systems provide only one-way data communications.
VSAT systems provide only one-way data communications.
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3G and 4G refer to the third and fourth generation of mobile phone technology.
3G and 4G refer to the third and fourth generation of mobile phone technology.
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Satellite systems are much slower than analog modems.
Satellite systems are much slower than analog modems.
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Devices using cellular technology can connect directly to the Internet.
Devices using cellular technology can connect directly to the Internet.
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The upload speed for satellite Internet is typically higher than 500 kb/s.
The upload speed for satellite Internet is typically higher than 500 kb/s.
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Multiplies the amount of bandwidth that a single strand of fiber can support and enables ______ communications over one strand of fiber.
Multiplies the amount of bandwidth that a single strand of fiber can support and enables ______ communications over one strand of fiber.
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Leased lines vary in price depending on the ______ required and the distance between the two connected paths.
Leased lines vary in price depending on the ______ required and the distance between the two connected paths.
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Private WAN infrastructure may include dedicated point-to-point leased lines and ______ links.
Private WAN infrastructure may include dedicated point-to-point leased lines and ______ links.
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Each channel can carry a ______ Gb/s multiplexed signal.
Each channel can carry a ______ Gb/s multiplexed signal.
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In North America, service providers use the T-carrier system to define the digital ______ of a serial copper media link.
In North America, service providers use the T-carrier system to define the digital ______ of a serial copper media link.
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Public WAN infrastructure often uses ______ access for broadband Internet.
Public WAN infrastructure often uses ______ access for broadband Internet.
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Data traveling over a public WAN should be protected using ______.
Data traveling over a public WAN should be protected using ______.
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A leased line is also known as a ______ link, which is a dedicated communication path.
A leased line is also known as a ______ link, which is a dedicated communication path.
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Service provider networks typically consist of high-bandwidth fiber-optic media using ______ standards.
Service provider networks typically consist of high-bandwidth fiber-optic media using ______ standards.
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For example, a T1 link supports ______ Mb/s.
For example, a T1 link supports ______ Mb/s.
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A modern development in fiber-optic technology for long-range communications is ______.
A modern development in fiber-optic technology for long-range communications is ______.
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Leased lines have been around since the ______, offering reliable point-to-point connections.
Leased lines have been around since the ______, offering reliable point-to-point connections.
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Leased lines can also be referred to as ______ circuits.
Leased lines can also be referred to as ______ circuits.
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One common type of packet switched link is ______ WAN.
One common type of packet switched link is ______ WAN.
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ISPs use various options to connect the local loop to the ______.
ISPs use various options to connect the local loop to the ______.
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Circuit-switched links may include technologies such as ______ or ISDN.
Circuit-switched links may include technologies such as ______ or ISDN.
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Dialup WAN access may be required when no other WAN technology is available, often using modems and analog telephone ______.
Dialup WAN access may be required when no other WAN technology is available, often using modems and analog telephone ______.
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Integrated Services Digital Network (ISDN) is a ______-switching technology that enables digital signal transmission.
Integrated Services Digital Network (ISDN) is a ______-switching technology that enables digital signal transmission.
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A modem modulates binary data into an analog signal at the ______ and demodulates it at the destination.
A modem modulates binary data into an analog signal at the ______ and demodulates it at the destination.
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The physical characteristics of the local loop limit the signal rate to less than ______ kb/s.
The physical characteristics of the local loop limit the signal rate to less than ______ kb/s.
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Time-division multiplexing (TDM) allows two or more signals to be transferred as ______ in one communication channel.
Time-division multiplexing (TDM) allows two or more signals to be transferred as ______ in one communication channel.
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ISDN changes the PSTN connections from carrying analog signals to ______ digital signals.
ISDN changes the PSTN connections from carrying analog signals to ______ digital signals.
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To use traditional local loops, copper cabling transports binary computer data through the voice telephone ______.
To use traditional local loops, copper cabling transports binary computer data through the voice telephone ______.
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A WAN built with an on-demand connection using a ______ can provide necessary connectivity.
A WAN built with an on-demand connection using a ______ can provide necessary connectivity.
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The WAN can connect local branches in the same city area, connect remote branches, or connect to a single ______.
The WAN can connect local branches in the same city area, connect remote branches, or connect to a single ______.
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The geographic scope of the WAN can be classified as local, regional, or ______.
The geographic scope of the WAN can be classified as local, regional, or ______.
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A private WAN offers the best ______ compared to public infrastructure.
A private WAN offers the best ______ compared to public infrastructure.
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Public Internet infrastructure is not as secure, but offers the most flexibility and the lowest ongoing ______.
Public Internet infrastructure is not as secure, but offers the most flexibility and the lowest ongoing ______.
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For a private WAN, it can either be dedicated or ______.
For a private WAN, it can either be dedicated or ______.
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The WAN can connect internal or external employees or ______.
The WAN can connect internal or external employees or ______.
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The traffic requirements of the WAN define what type of ______ must be supported.
The traffic requirements of the WAN define what type of ______ must be supported.
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Choosing between public and private infrastructure often depends on balancing security with ______.
Choosing between public and private infrastructure often depends on balancing security with ______.
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Frame Relay creates PVCs which are uniquely identified by a data-link connection identifier (DLCI) that ensures bidirectional communication between one DTE device to another, using ______.
Frame Relay creates PVCs which are uniquely identified by a data-link connection identifier (DLCI) that ensures bidirectional communication between one DTE device to another, using ______.
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Asynchronous Transfer Mode (ATM) is built on a ______-based architecture rather than on a frame-based architecture.
Asynchronous Transfer Mode (ATM) is built on a ______-based architecture rather than on a frame-based architecture.
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ATM cells contain a 5-byte ATM header followed by ______ bytes of ATM payload.
ATM cells contain a 5-byte ATM header followed by ______ bytes of ATM payload.
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A typical ATM line needs almost ______% greater bandwidth than Frame Relay to carry the same volume of network traffic.
A typical ATM line needs almost ______% greater bandwidth than Frame Relay to carry the same volume of network traffic.
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Ethernet is now a reasonable WAN access option, particularly thanks to newer Ethernet standards using ______ cables.
Ethernet is now a reasonable WAN access option, particularly thanks to newer Ethernet standards using ______ cables.
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The original maximum cable length for Ethernet was one kilometer, and with fiber-optic cable, the maximum length is ______ km using IEEE 10000Base-LX.
The original maximum cable length for Ethernet was one kilometer, and with fiber-optic cable, the maximum length is ______ km using IEEE 10000Base-LX.
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Cells in ATM technology are always a fixed length of ______ bytes.
Cells in ATM technology are always a fixed length of ______ bytes.
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When the cell is carrying segmented network layer traffic, the overhead is higher since the ATM switch must be able to ______ the packets at the destination.
When the cell is carrying segmented network layer traffic, the overhead is higher since the ATM switch must be able to ______ the packets at the destination.
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Match the following types of VPN access with their descriptions:
Match the following types of VPN access with their descriptions:
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Match the benefits of using VPNs with their descriptions:
Match the benefits of using VPNs with their descriptions:
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Match the following WAN connection options with their characteristics:
Match the following WAN connection options with their characteristics:
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Match the terms with their correct definitions regarding VPN tunnels:
Match the terms with their correct definitions regarding VPN tunnels:
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Match the following WAN types with their features:
Match the following WAN types with their features:
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Match the following WAN technologies with their descriptions:
Match the following WAN technologies with their descriptions:
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Match the WAN connection considerations with their focus areas:
Match the WAN connection considerations with their focus areas:
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Match the type of VPN connection with its typical use case:
Match the type of VPN connection with its typical use case:
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Match the following WAN access technologies with their bandwidth capabilities:
Match the following WAN access technologies with their bandwidth capabilities:
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Match the VPN characteristics with their implications:
Match the VPN characteristics with their implications:
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Match the following WAN options with their primary use case:
Match the following WAN options with their primary use case:
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Match the technologies with their WAN functionality:
Match the technologies with their WAN functionality:
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Match the following connection types with their specific characteristics:
Match the following connection types with their specific characteristics:
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Match the following WAN types with their security measures:
Match the following WAN types with their security measures:
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Match the following technologies with their application areas:
Match the following technologies with their application areas:
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Match the following WAN technologies with their characteristics:
Match the following WAN technologies with their characteristics:
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Match the following technologies with their primary data type:
Match the following technologies with their primary data type:
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Match the following technologies with their payload structure:
Match the following technologies with their payload structure:
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Match the following WAN technologies with their overhead characteristics:
Match the following WAN technologies with their overhead characteristics:
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Match the following technologies with their bandwidth requirements:
Match the following technologies with their bandwidth requirements:
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Match the following technologies with their maximum cable lengths:
Match the following technologies with their maximum cable lengths:
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Match the following data structures with the respective WAN type:
Match the following data structures with the respective WAN type:
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Match the following characteristics with their respective technologies:
Match the following characteristics with their respective technologies:
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Match the following ISDN interfaces with their descriptions:
Match the following ISDN interfaces with their descriptions:
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Match the following Frame Relay characteristics with their descriptions:
Match the following Frame Relay characteristics with their descriptions:
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Match the following ISDN applications with their purposes:
Match the following ISDN applications with their purposes:
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Match the following aspects of BRI with their measurements:
Match the following aspects of BRI with their measurements:
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Match the following ISDN characteristics with their benefits:
Match the following ISDN characteristics with their benefits:
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Match the following descriptions of WAN technologies with their types:
Match the following descriptions of WAN technologies with their types:
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Match the following Frame Relay features with their functions:
Match the following Frame Relay features with their functions:
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Match the following types of WAN technology with their characteristics:
Match the following types of WAN technology with their characteristics:
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Match the following metrics with their descriptions:
Match the following metrics with their descriptions:
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Match the following components with their functions:
Match the following components with their functions:
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Match the following connection types with their typical uses:
Match the following connection types with their typical uses:
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Match the following technologies with their advantages:
Match the following technologies with their advantages:
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Match the following descriptions with the correct technology:
Match the following descriptions with the correct technology:
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Match the following types of devices with their capabilities:
Match the following types of devices with their capabilities:
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Study Notes
WAN Services Overview
- WAN connections bridge local loops to enterprise edges, offering various options with distinct advantages, speeds, and costs.
- Enterprises can choose between private WAN infrastructure (e.g., dedicated leased lines, circuit-switched links like PSTN or ISDN) or public WAN infrastructure (e.g., DSL, cable, satellite).
- Data across public WANs should utilize VPNs for security.
Service Provider Network Infrastructure
- Service provider networks are largely built on high-bandwidth fiber-optic media, primarily using SONET or SDH standards.
- Dense Wavelength Division Multiplexing (DWDM) represents a new development in fiber-optic communication for long-range applications.
VPN Technology
- VPNs create encrypted connections over public networks, enabling secure access to corporate WANs, essential for teleworkers and remote offices.
- Unlike dedicated Layer 2 connections, VPNs utilize virtual tunnels routed through the Internet, connecting private networks to remote sites.
- Key benefits of VPNs include cost savings, enhanced security, scalability, and compatibility with broadband technologies.
- Two types of VPN access:
- Site-to-site VPNs: Connect entire networks, such as branch offices to headquarters.
- Remote-access VPNs: Allow telecommuters and mobile users secure access to corporate networks.
Selecting WAN Services
- Numerous considerations arise when choosing a WAN connection, including its purpose and specific service offerings.
- Service providers are beginning to offer Ethernet WAN services via fiber-optic cabling, leading to reduced costs, easy integration, and increased productivity.
- Ethernet WANs are gaining popularity as replacements for Frame Relay and ATM connections.
Private WAN Infrastructures and MPLS
- Multiprotocol Label Switching (MPLS) is a high-performance WAN technology that directs data using short path labels rather than traditional IP addresses.
- MPLS is termed "multiprotocol" due to its capability to carry various data formats, such as IPv4, IPv6, Ethernet, ATM, DSL, and Frame Relay.
- It utilizes labels to instruct routers on data packet handling, supporting diverse WAN technologies including T-carrier/E-carrier links, Carrier Ethernet, and more.
- MPLS serves primarily as a service provider WAN technology, facilitating multiple access technologies within an MPLS cloud.
Additional Media Considerations
- All discussed private WAN technologies employ either copper or fiber-optic media for communication.
VPN Technology
- VPNs (Virtual Private Networks) are essential for secure remote access to corporate WANs over public networks like the Internet.
- A VPN establishes an encrypted connection, using virtual tunnels instead of dedicated lines, to link private networks securely.
- Benefits of using VPNs include cost savings, enhanced security, scalability, and compatibility with broadband technologies.
- Two main types of VPN access:
- Site-to-Site VPNs: Connect entire networks, e.g., linking branch offices to headquarters.
- Remote-Access VPNs: Allow individual users like telecommuters to securely connect to company networks.
Choosing a WAN Link Connection
- Network administrators must consider the WAN's purpose and requirements when selecting appropriate connections.
- ISDN (Integrated Services Digital Network) may require a terminal adapter (TA) for connecting BRI (Basic Rate Interface) to routers.
ISDN Interfaces
- Basic Rate Interface (BRI): Comprises two 64 kb/s bearer channels (B) for voice/data, and one 16 kb/s delta channel (D) for signaling.
- Primary Rate Interface (PRI): In North America, it provides 23 B channels and one D channel, totaling 1.544 Mb/s.
- ISDN serves as a backup option for leased lines and increases capacity as needed; however, its popularity has declined due to alternatives like DSL.
Frame Relay
- Frame Relay is a Layer 2 NBMA (non-broadcast multiple access) WAN technology for connecting LANs.
- Offers data rates up to 4 Mb/s, with some providers offering higher speeds.
- Facilitates multiple site connections using Permanent Virtual Circuits (PVCs) with voice and data traffic.
VSAT Technology
- Very Small Aperture Terminal (VSAT) utilizes satellite communications to form private WANs for remote locations lacking traditional provider services.
- Operates via small satellite dishes in geosynchronous orbit, with signals traveling approximately 35,786 km.
DSL (Digital Subscriber Line)
- DSL leverages existing twisted-pair telephone lines for high-bandwidth, always-on Internet connections.
- Requires a DSL modem to convert Ethernet signals, and multiple subscriber lines are multiplexed via DSLAM in central offices.
- Widely utilized by IT departments to support remote workers after establishing links through ISPs.
Cable Internet
- Cable modems provide always-on connections using coaxial cables, offering higher bandwidth than traditional telephone lines.
- Installation involves connecting a computer or LAN router to the cable modem, which translates digital signals for transmission.
- CMTS (Cable Modem Termination System) is essential for sending and receiving cable modem signals within the network.
Wireless WAN Technologies
- Traditional wireless access was limited by range; advancements now include:
- Municipal Wi-Fi: Cities enabling networks for public use, often at reduced rates.
- WiMAX (IEEE 802.16): A newer technology providing high-speed broadband with extensive coverage, functioning similar to cellular networks.
Satellite Internet Services
- Ideal for rural areas lacking cable or DSL; VSATs enable two-way communications with upload speeds roughly one-tenth of 500 kb/s download speeds.
- Outperforms analog modems significantly in speed but may lag compared to DSL and cable services.
3G/4G Cellular Technology
- Cellular technology provides a wireless WAN solution for users in areas without other WAN access options.
- Devices such as phones, tablets, and laptops utilize radio waves for Internet connectivity through nearby mobile towers.
- Common terms include 3G/4G for third and fourth-generation cellular access and LTE (Long-Term Evolution) for advanced 4G technology.
WAN Services Overview
- WAN access connection options enable ISPs to link the local loop to the enterprise edge.
- Choices include private WAN infrastructures using dedicated leased lines or public WAN infrastructures utilizing broadband Internet via DSL, cable, or satellite.
- Data transfer over public WAN requires protection through VPNs for security.
Service Provider Network Infrastructure
- Composed of high-bandwidth fiber-optic media utilizing SONET or SDH standards.
- Dense Wavelength Division Multiplexing (DWDM) enhances fiber capacity by supporting over 80 channels, each carrying up to 10 Gb/s.
Private WAN Infrastructures
- Leased Lines: Long-established point-to-point connections leased from service providers, referentially called serial links, T1/E1, or T3/E3 lines.
- Bandwidth and distance determine costs, with a T1 link supporting 1.544 Mb/s.
Dialup Connections
- Used when no other technology is available, relying on modems and analog telephone lines.
- Converts digital binary data into analog signals and vice versa, with speeds typically under 56 kb/s.
Integrated Services Digital Network (ISDN)
- Circuit-switching technology allowing the PSTN to carry digital signals for higher capacity.
- Utilizes Time-Division Multiplexing (TDM) to transfer multiple signals in one channel.
WAN Selection Considerations
- Key questions when selecting WAN services include geographic scope (local, regional, global) and connection types (one-to-one, one-to-many, many-to-many).
- Traffic requirements, including type and performance metrics, are crucial in planning.
Private vs. Public Infrastructure
- Private WAN provides enhanced security; public WAN offers flexibility and lower costs.
- Decisions must include whether to use dedicated or switched connections based on specific business needs.
Frame Relay
- Creates Permanent Virtual Circuits (PVCs) identified by Data-Link Connection Identifiers (DLCIs) for secure communication between devices.
Asynchronous Transfer Mode (ATM)
- Uses a cell-based architecture (fixed cells of 53 bytes) suited for voice and video transmission.
- Requires approximately 20% more bandwidth than Frame Relay for similar traffic volumes due to additional overhead.
Ethernet WAN
- Recent Ethernet standards allow the use of fiber-optic cables, increasing potential maximum cable length significantly (up to 70 km with IEEE 1000BASE-ZX).
WAN Services Overview
- WAN access connection options provide distinct advantages and disadvantages based on technology, speed, and cost.
- Two primary methods to obtain WAN access:
- Private WAN Infrastructure: Includes dedicated point-to-point leased lines, circuit-switched links (PSTN, ISDN), and packet-switched links (Ethernet WAN, ATM, Frame Relay).
- Public WAN Infrastructure: Offered by service providers, includes broadband Internet via DSL, cable, and satellite.
VPN Technology
- VPNs (Virtual Private Networks) secure data traveling between corporate sites over public WANs by establishing encrypted connections.
- VPN tunnels, virtual connections routed through the Internet, replace dedicated Layer 2 links such as leased lines.
- Benefits of VPNs include:
- Cost savings
- Enhanced security
- Scalability
- Compatibility with broadband technology
- Two types of VPN access:
- Site-to-Site VPNs: Connects entire networks, e.g., branch office to headquarters.
- Remote-Access VPNs: Allows telecommuters and mobile users to securely access the company network over the Internet.
Choosing a WAN Link Connection
- Network administrators evaluate various factors, such as WAN purpose and required technologies, when selecting WAN connections.
- ISDN connections often need a terminal adapter (TA) for Basic Rate Interface (BRI) connections to routers.
ISDN Overview
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ISDN Interfaces:
- Basic Rate Interface (BRI): Offers two 64 kb/s bearer channels and one 16 kb/s delta channel for signaling.
- Primary Rate Interface (PRI): North America provides 23 B channels at 64 kb/s and one D channel, totaling up to 1.544 Mb/s.
- ISDN is used for additional capacity on leased lines and as backup in case of failures but has declined with the rise of DSL and other broadband services.
Private WAN Infrastructures
- Frame Relay: Layer 2 NBMA technology interconnecting LANs with data rates up to 4 Mb/s; utilizes Permanent Virtual Circuits (PVCs) identified by Data-Link Connection Identifiers (DLCI).
- Asynchronous Transfer Mode (ATM): Transfers voice, video, and data in a fixed-length cell structure (53 bytes); requires more bandwidth compared to Frame Relay for similar traffic.
- Ethernet WAN: Emerging as a viable WAN access option, especially with fiber-optic enhancements.
- Maximum cable lengths enhanced via fiber-optics: up to 5 km (IEEE 10000Base-LX) and 70 km (IEEE 1000BASE-ZX).
Public WAN Infrastructures
- Satellite Internet: Common in rural areas; provides two-way communication with specific upload and download speed characteristics (upload is slower).
- 3G/4G Cellular Technology: Connects remote users using radio waves to mobile towers; devices include phones, tablets, laptops, and routers.
- Long-Term Evolution (LTE): Advanced 4G technology offering faster data connectivity, part of the evolving cellular service landscape.
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Description
This quiz covers the fundamental concepts of WAN services, including the comparison of private and public WAN infrastructures. It also explores service provider network infrastructure, focusing on advancements like DWDM, and the importance of VPN technology for secure data transmission. Test your understanding of how these elements come together to support enterprise networking.