Syngress - Eleventh Hour Network+ Exam N10-004 Study Guide (11 ...

Internet Access Methods 113
EXAM WARNING
Other forms of DSL are very-high-speed digital subscriber line (VDSL), high-speed digital
subscriber line (HDSL), symmetrical high-speed digital line subscriber (SHDSL), ISDN digital
subscriber line (IDSL), and HDSL Second Generation (HDSL-2). You will have to be
familiar with ADSL and SDSL not only for the exam but also for your own use if you plan to
work on DSL. These are the most commonly used types and will surely be something you
will want to know about in more depth if the situation arises where you may be working
with this technology.
For the exam, you will need to know how to troubleshoot problems with DSL, although
DSL itself may not be the problem. Look for misleading types of questions that ask you
about DSL technology, although the questions are not essentially focused on that particular
technology. The Network+ exam is notorious for these types of scenario questions. Be
able to isolate what the cause of a problem may be, whether it be an ISDN, DSL, or WISP
(wireless ISP) connection based on the technology and the underlying network – as well
as problems may also be occurring there that are misleading you into the wrong answer.
Finally, make sure that you remember that DSL and ISDN are both digital technologies,
not analog.
Cable Modem
Broadband cable access requires the use of a modem designed to operate over
cable TV lines. Because the coaxial cable used by cable TV provides much greater
bandwidth than telephone lines, a cable modem can be used to achieve extremely
fast access to the Internet. Cable modems are commonly used in small and home
offices. Figure 7.1 shows a typical cable network setup.
Characteristics and features of cable modems are as follows:
■ Cable networks provide a shared access to the users on the network, so
heavy usage can slow it down, unlike DSL, which has dedicated user
access.
■ Because cable networks do not use preexisting phone lines in the home,
cable companies will have to install a line into your home (at an additional
cost) if one doesn’t already exist.
■ Cable networks provide speeds up to about 10 Mbps.
■ Even with shared access, cable is often faster than ADSL.
■ Cable networks are not available everywhere yet. DSL has more availability
at this time than cable networks.
EXAM WARNING
Some of the most common questions that you are likely to have to solve will be in the form
of how to troubleshoot network devices or which one is better and faster than the other.
Which one should you use and for what reasons Refer to Chapter 10, which discusses
how to troubleshoot networking devices.