Infrastructure (7) Flashcards
Which of the following types of wide area network (WAN) connection uses analog signaling and is limited to transmission speeds of 33.6 Kbps upstream and 56 Kbps downstream?
Public Switched Telephone Network (PSTN)
Integrated Services Digital Network (ISDN)
Digital Subscriber Line (DSL)
Cable broadband
Public Switched Telephone Network (PSTN)
The current industry standard transmission speed for modem communication using PSTN connections is 56 Kbps in one direction and 33.6 Kbps in the other. To achieve 56 Kbps, one of the devices must have a digital connection to the PSTN. ISDN, DSL, and cable broadband all support faster transmission speeds
Which of the following wide area network (WAN) technologies uses only digital signaling and uses a separate signaling channel for its control and synchronization?
Modem-to-modem
Integrated Services Digital Network (ISDN)
Layer 2 Tunneling Protocol (L2TP)
Integrated Services Digital Network (ISDN)
ISDN has a separate channel, referred to as the D channel, which devices use for control and synchronization. The other channels (or circuits) carry data and are referred to as B channels. Modem-to-modem communication uses in-band signaling, which means that both control/synchronization and data traffic are carried over the same circuit. L2TP and PPTP are tunneling, not WAN, protocols
Which of the following wide area network (WAN) technologies is sometimes referred to as 2B+D?
Digital Subscriber Line (DSL)
Integrated Services Digital Network (ISDN) Primary Rate Interface (PRI)
Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI)
Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI)
ISDN BRI is sometimes referred to as 2B+D. B channels are 64-Kbps circuits that carry user data. A single D channel carries control and synchronization information. An ISDN PRI connection has 23 B channels, not 2. DSL does not use B and D channels. T-1 circuits consist of 24 channels, all of which carry data and control information
Why does DSL (Digital Subscriber Line) technology support faster data transmissions than a standard Public Switched Telephone Network (PSTN) modem connection?
DSL does not perform cyclical redundancy check (CRC) functions and therefore has less overhead.
DSL performs only a single analog-to-digital conversion.
DSL uses a higher frequency range.
DSL uses a higher frequency range.
DSL technology provides higher data rates because it uses frequency ranges that are higher than the standard voice spectrum. DSL connections use from 10 kHz and above, whereas the standard voice spectrum uses 300 Hz to 4 kHz. DSL does not use separate control circuits and does not perform CRC functions. Also, DSL technology is strictly digital and does not require an analog-to-digital conversion
Which DSL (Digital Subscriber Line) technology can adjust its transmission speed based on line conditions?
HDSL
IDSL
RADSL
RADSL
Rate-Adaptive Digital Subscriber Line (RADSL) technology can adjust its rate of transmission based on line conditions. High-bit-rate Digital Subscriber Line (HDSL), Very high-rate Digital Subscriber Line (VDSL), and Internet Digital Subscriber Line (IDSL) do not use rate adaptive transmission
Which of the following wide area network (WAN) technologies uses broadband signaling?
Synchronous Optical Network (SONET)
Integrated Services Digital Network (ISDN)
Cable television (CATV)
Cable television (CATV)
CATV networks use broadband signaling, which enables many signals to occupy the same channel. DSL and ISDN do not use broadband signaling. SONET is a physical layer standard that defines fiber-optic connections
Alice’s company has 10 users who telecommute from home. They all have Integrated Services Digital Network Basic Rate Interface (ISDN BRI) configured and installed in their homes. They all need to transfer files between their homes and the corporate network. Each user connection has its two B channels combined for a total data transfer rate of 128 Kbps. Alice’s corporate network must be able to support all of these connections simultaneously. What service should Alice install at the corporate site, and how should she configure it to support the remote client connections?
Alice should install a single BRI connection and configure the access router to combine its B channels.
Alice should install five BRI connections and configure the access router to combine all ten B channels.
Alice should install a single PRI connection and configure the access router to combine all 23 B channels.
Alice should install a single PRI connection and configure the access router to combine all 23 B channels.
In this scenario, there are 10 users with BRI connections, each of which has its two B channels combined to provide a 128 Kbps transfer rate per user. To support simultaneous connections to the corporate site, Alice will need to install and configure a single PRI link to support the aggregation of multiple B channel connections. A single PRI link has 23 B channels and 1 D channel. Therefore, the router can support up to 11 inbound BRI sessions simultaneously, which is more than enough. Installing a single BRI at the corporate site would not enable multiple simultaneous BRI connections, and installing five BRI links, for a total of ten 64 Kbps B channels, would not support the ten 128 Kbps sessions that are required. Installing multiple PRI links is unnecessary since the site only has to support ten inbound BRI connections
Ed has been hired by a private company to connect two remote sites with a wide area network (WAN). Each of these sites has more than 200 users, and they all need to constantly transfer files across the WAN. One of the sites has a customer database that is accessed by both sites at all hours of the day. Access to the database and other information is time sensitive and constant. The company estimates that their aggregate bandwidth needs to be approximately 40 Mbps. Management says that they need to guarantee access to this information and that money is not a factor in the WAN implementation. Which WAN technology should Ed recommend for this scenario?
A standard modem-to-modem connection
A T-3 dedicated leased line
An ADSL (Asymmetrical Digital Subscriber Line) connection
A T-3 dedicated leased line
For this scenario, the best solution is a dedicated leased line connection. This is because the bandwidth requirements are constant and the data transfer rates are high. To support the 40 Mbps data rate, Ed should recommend a T-3 dedicated leased line, running at 44.735 Mbps. Standard modem connections, ADSL, and an ISDN PRI connection are all too slow
Ralph is an employee of a company that offers the option to telecommute from home. As a telecommuting employee, he needs to connect to the company network to access client information, transfer files, and send email through a virtual private network (VPN) connection. Ralph is investigating the different wide area network (WAN) services available for the remote connection before he implements one. His home is over 30 years old; the existing telephone wiring was not run through conduit, and the wiring seems to be deteriorating. Ralph has cable television (CATV) service, and his home is also approximately 20,000 feet from the nearest telephone central office. He wants to implement the fastest remote connection service possible, but cost is a factor in the decision. Which WAN technology should Ralph implement?
A dedicated leased line (fractional T-1)
A DSL (Digital Subscriber Line) connection
A broadband CATV connection
A broadband CATV connection
In this scenario, the best solution is for Ralph to use his existing CATV service the remote connection. CATV offers faster data rates than standard modem-to-modem service and supports VPN connections. A dedicated fractional T-1 line is expensive and is not typically used for remote user connections. Since Ralph’s telephone lines are not run through conduit and the distance to the central office is more than 18,000 feet, he probably cannot use DSL technology, because it requires good-quality lines and close proximity to a central office
Alice is the administrator of a corporate network. The company has one main site and two branch offices, and Alice is responsible for implementing WAN connections between them. The two branch offices need to upload financial information to the main office at the end of each day. This information transfer consists of database files totaling 20 to 30 GB per site. Other than the exchange of financial information, no other user traffic will be transferred between the sites, and, for security reasons, the management wants to automatically disconnect the link when it is not in use, without having to manually unplug the service cable. Cost is a factor in determining which wide area network (WAN) technology to use. Which of the following WAN technologies best suits the company’s needs?
A Digital Subscriber Line (DSL) connection
A broadband cable television (CATV) connection
An Integrated Services Digital Network (ISDN) Primary Rate Interface (PRI) connection
An Integrated Services Digital Network (ISDN) Primary Rate Interface (PRI) connection
For this scenario, the only solution that meets all the company’s needs is an ISDN PRI connection. All of the specified options, except for the PSTN modem connection, provide sufficient bandwidth for the application. However, only the ISDN and PSTN links can be disconnected when not in use. Therefore, ISDN is the only possibility
Which of the following wide area network (WAN) connection technologies uses analog signaling?
Public Switched Telephone Network (PSTN)
Integrated Services Digital Network (ISDN)
Cable television (CATV)
Public Switched Telephone Network (PSTN)
PSTN is an analog, circuit-switched network. ISDN, CATV, DSL, and SONET are all digital networks
Which of the following wide area network (WAN) technologies provides circuit-switched physical layer connections? (Choose all correct answers.)
Public Switched Telephone Network (PSTN)
Integrated Services Digital Network (ISDN)
Digital Subscriber Line (DSL)
Leased line
Public Switched Telephone Network (PSTN)
Integrated Services Digital Network (ISDN)
Circuit-switching WAN technologies set up and maintain connections between end systems for the duration of a session. The WAN technologies that can use this type of connection are PSTN and ISDN. Leased lines, such as a T-1, are dedicated connections. DSL uses packet switching, not circuit switching
If you want to allow both voice and data traffic to be transmitted across the same Digital Subscriber Line (DSL) connection, what type of device is required at the customer site?
A signal terminator
A coder/decoder (CODEC) device
A splitter
A splitter
In a DSL connection, a signal splitter is needed at the customer site to separate the lower frequency voice range from the higher frequencies used by data traffic. The higher frequency signals are handled at the central office by a DSLAM device. Lower frequency signals carrying voice traffic are handled at the central office by a CODEC device. A signal terminator is not required by DSL
What are the two main factors that affect DSL (Digital Subscriber Line) transmission rates?
Signal termination
Distance to the nearest central office
Line conditions
Line reflection
Distance to the nearest central office
Line conditions
There are two factors that affect DSL transmission rates. The first is the distance to the nearest central office, and the second is the condition and quality of the line. For DSL to achieve higher data rates, the site must be close to the central office and use good-quality lines for signal transmission. The other options are not factors relating to DSL transmission
Which of the following statements are true about the Point-to-Point Protocol (PPP)? (Choose all correct answers.)
PPP supports both clear text and encrypted authentication.
PPP supports encrypted authentication only.
PPP supports Internet Protocol (IP) traffic only.
PPP supports multiple network layer protocols.
PPP supports both clear text and encrypted authentication.
PPP supports multiple network layer protocols.
PPP supports both clear text and encrypted password authentication. It also supports multiple network layer protocols
