Infrastructure (8) Flashcards
A T-3 leased line connection is the equivalent of how many T-1 connections?
7
14
28
28
A T-3 leased line connection is the equivalent of 28 T-1 connections. Each T-1 consists of 24 channels, so a T-3 has a total of 672 channels (28 × 24), for an overall transfer rate of 44.736 Mbps
Which of the following wide area network (WAN) technologies is considered to be both a packet-switched and a circuit-switched service?
PSTN
T-1 leased line
ATM
ATM
Asynchronous Transfer Mode (ATM) is a cell-switched protocol that is designed to carry voice, data, and video traffic by splitting it into uniform 53-byte cells. To this degree, it can be considered a packet-switched service. However, it is unlike traditional packet-switched protocols, which use variable-sized packets. ATM can also be called a circuit-switched service, because the end systems must create a virtual circuit before they transfer any data. Public Switched Telephone Network (PSTN) and T-1 leased lines are both circuit-switched network types, while Metropolitan Ethernet is packet-switched
Which of the following is the U.S. standard for synchronous data transmissions that defines data rates designated by optical carrier levels, such as OC-3, OC-12, OC-48, and OC-192?
SDH
SONET
ISDN
SONET
The Synchronous Optical Networking (SONET) standard defines a base data transfer rate of 51.84 Mbps, which is multiplied at the various optical carrier levels. An OC-3 connection therefore runs 155.52 Mbps, an OC-12 at 622.08 Mbps and so forth. The Synchronous Digital Hierarchy (SDH) is the European equivalent of SONET. Integrated Services Digital Network (ISDN) is a service that combines voice and data services using the Public Switched Telephone Network (PSTN), and Asynchronous Transfer Mode (ATM) is cell-switched protocol defining a combined voice, data, and video service
Which of the following technologies can replace leased lines, such as T-1s, by multiplexing signals as packets switched through virtual circuits in a cloud?
E-1s
Frame relay
ATM
Frame relay
Frame relay is a packet switching service that uses a single leased line to replace multiple leased lines by multiplexing traffic through a cloud. The service can create virtual circuits connecting the subscriber’s network to multiple destinations, eliminating the need for a dedicated leased line to each remote site. An E-1 is the European equivalent to a T-1 leased line, which does not replace multiple T-1s. Asynchronous Transfer Mode (ATM) is a cell-switching WAN technology, and Point-to-Point Protocol (PPP) is a protocol that provides a data link layer connection between two end systems. Neither is a replacement for multiple T-1s
Which of the following is a wide area networking mechanism that assigns labels to packets and forwards them based on those labels, rather than addresses?
Frame relay
MPLS
ATM
MPLS
Multiprotocol Label Switching (MPLS) is a data transfer mechanism that assigns labels to individual packets and then routes the packets based on those labels. Frame relay, Asynchronous Transfer Mode (ATM), and Point-to-Point Protocol over Ethernet (PPPoE) do not assign labels to packets
In telecommunications, the term broadband has had a variety of definitions over the years. Which of the following is not one of the standard definitions of the term?
A medium that connects to the Internet at high speed and is always on
A medium that carries a wide range of frequencies
A medium that uses a cable with a relatively large diameter
A medium that uses a cable with a relatively large diameter
The term broadband has nothing to do with the width of the cable. However, the term as been used to refer to a transmission medium that carries multiple signals, that carries a wide range of frequencies, that is faster than a dial-up modem, and that provides an always-on, high-speed connection to the Internet
Integrated Services Digital Network (ISDN) offers two types of services. What are they? (Choose all correct answers.)
TE1
TA
BRI
PRI
NT1
BRI
PRI
The two types of ISDN services are Basic Rate Interface (BRI) and Primary Rate Interface (PRI). Terminal Equipment 1 (TE1), terminal adapter (TA), Network Termination 1 (NT1) are all terms for ISDN hardware devices
Which two of the following constructs provide roughly the same function? (Choose two correct answers.)
SIP trunk
CSU/DSU
VoIP gateway
Smart jack
VPN concentrator
SIP trunk
VoIP gateway
A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network. A VoIP gateway provides a connection between an IP network and the Public Switched Telephone Network (PSTN). Both of these provide a conduit between a subscriber’s private network and the network furnished by a service provider. A CSU/DSU is a device that provides a router on a private network with access to a leased line. A smart jack provides signal conversion, diagnostic testing, and other capabilities to leased line subscribers. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations
Which of the following technologies enables virtual private network (VPN) clients to connect directly to each other, as well as to the VPN server at the home site?
VPN concentrator
DMVPN
SIP trunk
DMVPN
VPN typically enables remote clients to connect to a VPN router at a central site, much like the star topology of a local area network, in which computers are all connected to a central switch. Dynamic multipoint virtual private network (DMVPN) is a technology that creates a mesh topology between the remote VPN sites, enabling the remote sites to connect directly to each other, rather than to the central VPN server. A virtual private network (VPN) concentrator is a type of router that enables multiple client systems to access a network from remote locations. A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network. Multiprotocol Label Switching (MPLS) is a data transfer mechanism that assigns labels to individual packets and then routes the packets based on those labels
Which of the following wide area network (WAN) transmission media is least susceptible to attenuation?
Copper
Fiber optic
Wireless
Fiber optic
Attenuation is the weakening of a signal as it travels over a transmission medium. Fiber-optic cables can carry signals for great distances with little attenuation, far less than any copper medium. Wireless and satellite media, by transmitting signals through air, suffer the most attenuation of any of these options
Which of the following statements about PPPoE are not true? (Choose all correct answers.)
PPPoE encapsulates Ethernet frames within PPP packets.
PPPoE enables multiple users on an Ethernet network to share a single Internet connection.
PPPoE requires a server on the Ethernet network that functions as the middleman between the LAN and the Internet service provider’s (ISP’s) network.
The PPPoE connection process consists of two stages: negotiation and establishment.
PPPoE encapsulates Ethernet frames within PPP packets.
The PPPoE connection process consists of two stages: negotiation and establishment.
PPPoE encapsulates PPP within Ethernet frames, not the other way around. The two stages of the PPPoE connection process are discovery and session. PPPoE does enable multiple users to share an Internet connection, and it requires a PPPoE server that initiates the PPP connection to the ISP’s network
Which of the following is the European equivalent of the Synchronous Optical Networking (SONET) standard in the United States?
SDH
OC-3
E-3
SDH
Synchronous Digital Hierarchy (SDH) is the European equivalent of SONET. Optical carrier 3 (OC-3) is one of the SONET data rates. E-3 is the European equivalent of the T-3 connection in the United States. Asynchronous Transfer Mode (ATM) is a cell-switched protocol that is designed to carry voice, data, and video traffic by splitting it into uniform 53-byte cells
Which of the following is the device that provides the interface between a local area network (LAN) and a wide area network (WAN)?
QSFP
CSU/DSU
SIP trunk
CSU/DSU
A channel service unit/data service unit (CSU/DSU) is a device that provides a LAN router on a private network with access to a leased line WAN connection. Quad Small Form-Factor Pluggable (QSFP) is a standard for a type of modular transceiver, often used on fiber-optic installations. A Session Initiation Protocol (SIP) trunk provides a connection between the private and public domains of a unified communications network, such as a LAN and the Public Switched Telephone Network (PSTN). An intrusion detection system/intrusion prevention system (IDS/IPS) is a network hardware or software security appliance that detects malicious activity and attempts to block it
Which of the following terms describes a leased line subscription that consists of only part of a T-1?
B channel
OC-1
Fractional T-1
Fractional T-1
A subscription to part of the T-1 leased line is called a fractional T-1 service. This service enables you to purchase some of the 24 DS0 channels in a T-1 connection. An E-1 is the European version of a T-1. A B channel is part of an Integrated Services Digital Network (ISDN) service, not a T-1. An OC-1 is a fiber-optic connection on the Synchronous Optical Network (SONET) service
Multiprotocol Label Switching (MPLS) is sometimes said to operate between two layers of the Open Systems Interconnection (OSI) model. Between which two layers is it usually said to function?
Physical and data link
Data link and network
Network and transport
Data link and network
MPLS is a data-carrying service that is often said to operate between the data link layer and the network layer. It is therefore sometimes called a layer 2.5 protocol. MPLS can be used to carry IP datagrams as well as Ethernet, Asynchronous Transfer Mode (ATM), and Synchronous Optical Network (SONET) traffic
Which of the following wide area networking (WAN) services provides the fastest transfer rate?
E-1
T-3
OC-1
OC-1
An OC-1 connection provides the fastest transfer rate at 51.84 Mbps. An E-1 connection is 2.048 Mbps. A T-3 is 44.736 Mbps, and a T-1 is 1.544 Mbps
To which of the following Internet connection types does a specification called DOCSIS apply?
Dial-up modem
DSL
Cable broadband
Cable broadband
The Data Over Cable Service Interface Specification (DOCSIS) is a telecommunications standard that defines the manner in which data is to be transmitted over a cable television system. DOCSIS does not apply to dial-up modem, Digital Subscriber Line (DSL), and Integrated Services Digital Network (ISDN) connections
Which of the following are types of circuits offered by frame relay services? (Choose all correct answers.)
SRV
PVC
SVC
UPC
PVC
SVC
Frame relay services offer permanent virtual circuits (PVCs) and switched virtual circuits (SVCs). SRV is a resource record type in the Domain Name System (DNS), and an ultra-polished connector (UPC) is a type of fiber-optic cable connector
Which of the following statements best explains why it became necessary to develop Point-to-Point Protocol over Ethernet (PPPoE)?
Internet service providers wanted customers to be able to run Ethernet on their home networks.
Local area network (LAN) administrators wanted to reduce network overhead by using the smaller PPP frame.
Internet service providers needed PPP’s authentication and encryption services for cable broadband and Digital Subscriber Line (DSL) customers.
Internet service providers needed PPP’s authentication and encryption services for cable broadband and Digital Subscriber Line (DSL) customers.
Cable broadband and DSL subscribers typically connect to ISP networks that run Ethernet, but Ethernet has no built-in authentication or encryption mechanisms. PPP has the ability to use external authentication and encryption protocols, so by encapsulating PPP within Ethernet frames, users are able to log on to the ISP network securely. PPPoE has nothing to do with the subscriber’s internal home network, which can run standard Ethernet. PPPoE does not replace the Ethernet frame with PPP, so it would not reduce network overhead. LAN users do not share files using PPP
Which of the following types of wide area network (WAN) connections commonly use Point-to-Point Protocol over Ethernet (PPPoE)? (Choose all correct answers.)
Leased lines
SONET
Cable broadband
Digital Subscriber Line (DSL)
Cable broadband
Digital Subscriber Line (DSL)
Cable broadband and DSL subscribers typically connect to ISP networks that run Ethernet, but Ethernet has no built-in authentication or encryption mechanisms. PPP has the ability to use external authentication and encryption protocols, so by encapsulating PPP within Ethernet frames, users are able to log on to the ISP network securely. Leased lines, such as T-1s, and Synchronous Optical Network (SONET) connections do not use Ethernet connections, so they have no need for PPPoE
Which of the following devices often provides diagnostic testing capabilities at the demarcation point of a leased line wide area network (WAN) service?
SIP trunk
Media converter
Smart jack
Smart jack
A smart jack is a device located at the demarcation point of a leased line that can provide additional functions, such as signal conversion, diagnostic testing, and other capabilities. A Session Initiation Protocol (SIP) trunk is a connection to a Voice over Internet Protocol (VoIP) service provider. A media converter is a local area networking devices that connects different cable types to the same network. An AAA server provides authentication, authorization, and accounting services for remote access servers
Which of the following wide area network (WAN) services typically uses a switched fabric that was called a cloud long before the term came into general use?
Fractional T-1
SONET
Frame relay
Frame relay
Frame relay is a packet switching service that uses a single leased line to replace multiple leased lines by multiplexing traffic through a cloud. Asynchronous Transfer Mode (ATM) uses a switched fabric, but it is not referred to as a cloud. A fractional T-1 is part of a leased line that connects two points, so there is no switching involved and no cloud. SONET is a physical layer standard that defines fiber-optic connections; it does not call for switching or use the term cloud
Which of the following wide area network (WAN) services uses uniformly sized, 53-byte packets called cells?
ATM
Frame relay
T-1
ATM
Asynchronous Transfer Mode (ATM) transfers data using uniformly sized cells rather than same-sized packets. Frame relay uses variable-sized packets, and Point-to-Point Protocol over Ethernet (PPPoE) uses variable-sized Ethernet frames. A T-1 is a circuit-switched connection that does not use packets or cells
