-
What is 10/100 shown on the network PCI
card? (back to
FAQ | ABC's)
10 and 100 are two
different standard of data transferring rate on the PCI
card. Obviously, 100 is much faster than 10. Normally
speaking, today’s PCI card could automatically adjust the
speed to either 10 or 100Mbps, which depends on the
traffic they encounter.
-
What is Ad-hoc mode?
(back to FAQ |
ABC's)
A peer-to-peer
configuration in which a group of wireless devices
communicate directly with each other without the use of an
access point.
-
What is ARP? (back to
FAQ |
ABC's)
Short for Address
Resolution Protocol, a TCP/IP
protocol used to convert an
IP
address into a physical address (called a
DLC
address), such as an Ethernet address. A host wishing to obtain a physical address
broadcasts an ARP request onto the TCP/IP
network. The host on the network that has the IP address
in the request then replies with its physical hardware
address.
-
What is BNC? (back to
FAQ |
ABC's)
A BNC (Bayonet
Neil-Concelman, or sometimes British Naval Connector)
connector is used to connect a computer to a
coaxial cable in a
10BASE-2
Ethernet network. 10BASE-2 is a 10 MHz
baseband network on a cable extending up to 185
meters - the 2 is a rounding up to 200 meters - without a
repeater cable. 10BASE-2 Ethernets are also known as " Thinnet ",
"thin Ethernet", or "cheapernets". The wiring in this type
of Ethernet is thin, 50 ohm, baseband coaxial cable. The
BNC connector in particular is generally easier to install
and less expensive than other coaxial connectors.
-
What is CAM? (back to
FAQ |
ABC's)
Short for channel
access method, a protocol for how data is transmitted in the
bottom two layers of the OSI
model. CAMs describe how networking systems put
data on the network media, how low-level errors are dealt
with, and how the network polices itself. Polling, contention and token passing are three examples of CAMs.
-
What is CHAP? (back to
FAQ |
ABC's)
CHAP takes a more sophisticated and
secure approach to authentication by creating a unique
challenge phrase (a randomly generated string) for each
authentication. The challenge phrase is combined with
device host names using one-way hashing functions to
authenticate in way where no static secret information is
ever transmitted over the wire. Because all transmitted
information is dynamic, CHAP is significantly more robust
than PAP.
Another advantage of CHAP over PAP is
that CHAP can be set up to do repeated midsection
authentications. This is useful for dial-up PPP sessions
and other sessions where a port may be left open even
though the remote device has disconnected. In this case,
its possible for someone else to pick up the connection
mid-session simply by establish physical connectivity.
-
What is CSMA/CA?
(back to FAQ |
ABC's)
Collision is the
situation that occurs when two or more devices attempt to
send a signal along the same channel at the same time. The result of a
collision is generally a garbled message. All computer networks require some sort of mechanism to
either prevent collisions altogether or to recover from
collisions when they do occur. CSMA/CA, which stands for
Carrier Sense Multiple Access with Collision Avoidance is
a Media Access Protocol which get rid of the problem of
the collision.
-
What is DAA? (back to
FAQ |
ABC's)
Short for Data
Access Arrangement, part of a modem system for interfacing with a telephone network. The DAA
provides the analog circuits that electrically isolate the
modem from the phone line, separating the modem from the
telephone line higher voltage. The FCC requires this feature of any device that connects to the PSTN, including
fax machines and set-top boxes, and most manufacturers build
modems around an FCC-approved DAA design.
-
What is DHCP?
(back to FAQ |
ABC's)
Short for Dynamic Host Configuration Protocol, a
communication protocol that dynamically or automatically
assigns IP addresses to devices located on the network. With
DHCP a device can have different IP address every time it
connects to a network. DHCP also supports static and dynamic
IP addresses on the same network. DHCP's purpose is to
enable individual computers on an IP network to extract
their configurations from a server (the 'DHCP server') or
servers, in particular, servers that have no exact
information about the individual computers until they
request the information. The overall purpose of this is to
reduce the work necessary to administer a large IP network.
The most significant piece of information distributed in
this manner is the IP address.
DHCP uses the concept of a "lease" or
amount of time that a given IP address will be valid for a
computer. The lease time can vary depending on how long a
user is likely to require the Internet connection at a
particular location. It's especially useful in
education and other environments where users change
frequently. Using very short leases, DHCP can dynamically
reconfigure networks in which there are more computers than
there are available IP addresses.
-
What is DMZ?
(back to FAQ |
ABC's)
Short for demilitarized zone, a
computer or small sub-network that sits between a trusted
internal network, such as a corporate private LAN,
and an untrusted external network, such as the public Internet.
Typically, the DMZ contains devices
accessible to Internet traffic, such as Web (HTTP) servers, FTP servers, SMTP (e-mail) servers and DNS servers.
-
What is DNS? (back to
FAQ |
ABC's)
Domain Name System
(DNS) is used to match internet computer names to their
corresponding IP numbers. DNS allows users to type a
computer name, such as www.company.com, instead of and IP number, such
as 192.168.53.3, to access a computer.
Static DNS is the core of the system;
in the simplest cases, IP addresses are permanently
assigned to specific computers, and are seldom changed.
When a new static IP address is generated, it can take
several days to propagate as a known address out to all
the domain name servers embedded within the Internet's
infrastructure. This is not unlike setting up a phone
system for a new business; after the phone company puts
the system in place, there is some delay before the
company's main number appears in the phone directories.
Dynamic DNS is an advanced technology
that brings dynamic update capabilities to the
traditionally static Domain Name System. This dynamic
update allows any domain name to be immediately mapped and
re-mapped to changing IP addresses anytime required. This
provides necessary flexibility for all Internet users by
allowing ordinary PCs on the edge of the Internet to
communicate effectively using the same domain name even if
the underlying IP addresses may be changing. This is
important for people who move between computing locations
frequently, or for those who are behind routers that serve
dynamically allocated IP addresses to resident computers
(DHCP).
-
What is DTMF? (back to
FAQ |
ABC's)
Short for Dual Tone
Multi-Frequency, the system used by touch-tone telephones.
DTMF assigns a specific frequency, or tone, to each key so
that it can easily be identified by a
microprocessor.
-
What is DSSS? (back to
FAQ |
ABC's)
Acronym for
direct-sequence spread spectrum. DSSS is one of two types
of spread spectrum radio, the other being frequency-hopping spread spectrum. DSSS is a
transmission technology used in LAWN transmissions where a data signal at the
sending station is combined with a higher data rate bit
sequence, or chipping code, that divides the user data
according to a spreading ratio. The chipping code is a
redundant bit pattern for each bit that is transmitted,
which increases the signal's resistance to interference.
If one or more bits in the pattern are damaged during
transmission, the original data can be recovered due to
the redundancy of the transmission.
-
What is Frequency band?
(back to FAQ |
ABC's)
Frequency
band means a band of adjacent radio
frequencies. Only those devices with same
frequency band could communicate with each other.
-
What is ICMP? (back to
FAQ |
ABC's)
Short for Internet
Control Message Protocol, an extension to the Internet Protocol (IP) defined by RFC
792. ICMP supports packets containing error, control, and
informational messages. The PING command, for example, uses ICMP to test an Internet connection.
-
What is
IEEE802.11b and IEEE802.11g wireless network?
(back to FAQ |
ABC's)
They are two
different technical standard of data transferring rate on
the wireless network. b could accept transfer rate up to
11Mbps, while g could accept up to 54Mbps. Mostly
speaking, products with standard g are compatible to both
b and g, while those with standard b can communicate well
with only b.
-
What
is Infrastructure Mode? (back to
FAQ |
ABC's)
A configuration in which a wireless network
communicates with a wired network via an access point.
-
What is IPSec? (back to
FAQ |
ABC's)
Short for IP
Security, a set of
protocols developed by the IETF to support secure exchange of packets at the IP
layer. IPsec has been deployed widely to implement Virtual Private Networks (VPNs).
-
What is IRQ? (back to
FAQ |
ABC's)
Abbreviation of
interrupt request line, and pronounced I-R-Q. IRQs are hardware lines over which devices can send interrupt signals to the
microprocessor. When you add a new device to a PC,
you sometimes need to set its IRQ number by setting a DIP
switch. This specifies which interrupt line the
device may use. IRQ conflicts used to be a common problem
when adding
expansion boards, but the Plug-and-Play
specification has removed this headache in most cases.
-
What is L2TP? (back to
FAQ |
ABC's)
Short for Layer Two
(2) Tunneling Protocol, an extension to the PPP protocol that enables ISPs to operate Virtual Private Networks (VPNs). L2TP merges the best features of two other
tunneling protocols: PPTP from Microsoft and L2F
from Cisco Systems. Like PPTP, L2TP requires that
the ISP's routers support the protocol.
-
What is MDI? (back to
FAQ |
ABC's)
It stands for
medium dependent interface, which is an Ethernet port connection that allows
network hubs or switches to connect to other hubs or switches
without a null-modem, or crossover, cable.
-
What is MDI-X? (back to
FAQ |
ABC's)
Short for medium
dependent interface crossover, an Ethernet port connection that allows networked end stations (i.e., PCs or
workstations) to connect to each other using a
null-modem, or crossover, cable.
-
What is MNP? (back to
FAQ |
ABC's)
Abbreviation of
Microcom Networking Protocol, a
communications protocol developed by Microcom,
Inc., that is used by many high-speed
modems. MNP
supports several different classes of
communication, each higher class providing additional
features. Modems can support one or more
classes. Class 4 provides
error detection and automatically varies the
transmission speed based on the quality of the line. Class
5 provides
data compression. Class 6 attempts to detect
the highest transmission speed of the modem at the other
end of the connect and transmit at that speed.
The most common levels of MNP support
are Class 4 and Class 5, frequently called MNP-4 and
MNP-5. Using the data compression techniques provided by
MNP-5,
devices can double normal transmission speeds.
Because MNP is usually built into the modem
hardware, it affects all
data transmission. In contrast,
software
protocols, such as
Xmodem and
Kermit, affect only
file transfer operations.
-
What is NAT? (back to
FAQ |
ABC's)
It stands for
Network Address Translation, which is the network
protocol. When the explosion of the Internet and the
increase in
home networks and business networks today, the
number of available IP addresses is simply not enough. The
obvious solution is to redesign the address format to
allow for more possible addresses. This is being developed
(called IPv6), but will take several years to implement
because it requires modification of the entire
infrastructure of the Internet.
This is where NAT (RFC
1631) comes to the rescue. Network Address
Translation allows a single device, such as a
router, to act as an agent between the Internet
(or "public network") and a local (or "private") network.
This means that only a single, unique IP address is
required to represent an entire group of computers.
-
What is NOS? (back to
FAQ |
ABC's)
It means Network
Operating System, which straightly means the operating
system which supports network, such as Novell, Citrx and
Cisco.
-
What is NTP? (back to
FAQ |
ABC's)
Short for Network
Time Protocol, an Internet standard
protocol (built on top of
TCP/IP) that assures accurate synchronization
to the millisecond of computer clock times in a network of
computers. Based on UTC,
NTP synchronizes
client
workstation clocks to the U.S. Naval
Observatory Master Clocks in Washington, DC and Colorado
Springs CO. Running as a continuous
background client program on a computer, NTP
sends periodic time requests to
servers, obtaining server time stamps and using
them to adjust the client's clock.
-
What is OFDM? (back to
FAQ |
ABC's)
Short for
Orthogonal Frequency Division Multiplexing, an FDM
modulation technique for transmitting large
amounts of digital data over a radio wave. OFDM works by
splitting the radio signal into multiple smaller
sub-signals that are then transmitted simultaneously at
different frequencies to the receiver. OFDM reduces the
amount of crosstalk in signal transmissions. 802.11a
WLAN technology uses OFDM.
-
What is PAP? (back to
FAQ |
ABC's)
Password
authentication protocol (PAP) and challenge handshake
authentication protocol (CHAP) are both used to
authenticate PPP sessions and can be used with many VPNs.
Basically, PAP works like a standard login procedure; the
remote system authenticates itself to the using a static
user name and password combination. The password can be
encrypted for additional security, but PAP is subject to
numerous attacks. In particular, since the information is
static, it is subject to password guessing as well as
snooping.
-
What is PPP? (back to
FAQ |
ABC's)
Short for
Point-to-Point Protocol, a method of connecting a
computer to the Internet. PPP is more stable than the older
SLIP protocol and provides error checking features.
Working in the
data link layer of the OSI model, PPP sends the
computer's TCP/IP packets to a server that puts them onto the Internet.
-
What is PPPoE? (back to
FAQ |
ABC's)
PPPoE
(Point-to-Point Protocol over Ethernet) is a specification
for connecting multiple computer users on an
Ethernet
local area network to a remote site through
common
customer premises equipment, which is the
telephone company's term for a
modem and similar devices. PPPoE can be used to
have an office or building-full of users share a common
Digital Subscriber Line (DSL),
cable modem, or
wireless> connection to the Internet. PPPoE
combines the Point-to-Point Protocol (PPP),
commonly used in dialup connections, with the Ethernet
protocol, which supports multiple users in a local area
network. The PPP protocol information is encapsulated
within an Ethernet
frame. These protocols are popular with the
service providers because they make the broadband
connection look like a dial-up connection from an
accounting and billing perspective. Also, they let the
service provider get more users onto the same facilities
by logging off users that have no activity.
PPPoE has the advantage that neither
the telephone company nor the Internet service provider (ISP)
needs to provide any special support. Unlike dialup
connections, DSL and cable modem connections are "always
on." Since a number of different users are sharing the
same physical connection to the remote service provider, a
way is needed to keep track of which user traffic should
go to and which user should be billed. PPPoE provides for
each user-remote site session to learn each other's
network addresses (during an initial exchange called
"discovery"). Once a session is established between an
individual user and the remote site (for example, an
Internet service provider), the session can be monitored
for billing purposes. Many apartment houses, hotels, and
corporations are now providing shared Internet access over
DSL lines using Ethernet and PPPoE.
-
What is PPTP? (back to
FAQ |
ABC's)
Short for
Point-to-Point Tunneling Protocol, a new technology for
creating
Virtual Private Networks (VPNs), developed
jointly by
Microsoft Corporation, U.S. Robotics, and
several
remote access vendor companies, known
collectively as the PPTP Forum. A VPN is a private
network of computers that uses the public
Internet to connect some
nodes. Because the Internet is essentially an
open network, the Point-to-Point Tunneling Protocol (PPTP)
is used to ensure that messages transmitted from one VPN
node to another are secure. With PPTP, users can dial in
to their corporate network via the Internet.
-
What is RIP? (back to
FAQ |
ABC's)
The Routing Information Protocol, or
RIP, as it is more commonly called, is one of the most
enduring of all routing protocols. RIP is also one of the
more easily confused protocols because a variety of
RIP-like routing protocols proliferated, some of which
even used the same name! RIP and the myriad RIP-like
protocols were based on the same set of algorithms that
use distance vectors to mathematically compare routes to
identify the best path to any given destination address.
These algorithms emerged from academic research that dates
back to 1957.
Today's open standard version of RIP,
sometimes referred to as IP RIP, is formally defined in
two documents: Request For Comments (RFC) 1058 and
Internet Standard (STD) 56. As IP-based networks became
both more numerous and greater in size, it became apparent
to the Internet Engineering Task Force (IETF) that RIP
needed to be updated.
Consequently, the IETF released RFC
1388 in January 1993, which was then superceded in
November 1994 by RFC 1723, which describes RIP 2 (the
second version of RIP). These RFCs described an extension
of RIP's capabilities but did not attempt to obsolete the
previous version of RIP. RIP 2 enabled RIP messages to
carry more information, which permitted the use of a
simple authentication mechanism to secure table updates.
More importantly, RIP 2 supported subnet masks, a critical
feature that was not available in RIP.
-
What is Roaming?
(back to FAQ |
ABC's)
The ability to take a wireless device from one access
point's range to another without losing the connection.
-
What is SPI? (back to
FAQ |
ABC's)
Short for serial
peripheral Interface, a
full-duplex
synchronous
serial interface for connecting low-/medium-bandwidth
external devices using four wires.
-
What is Tx and Rx?
(back to FAQ |
ABC's)
Tx means transmit,
and Rx means receive.
-
What is UI? (back to
FAQ |
ABC's)
UI stands for user
interface. It is the junction between a
user and a computer program. An interface is a set of
commands or menus through which a user communicates with a
program. A command-driven interface is one in which you
enter commands. A menu-driven interface is one in which you
select command choices from various menus displayed on the
screen.
The user interface is one of the most
important parts of any program because it determines how
easily you can make the program do what you want. A
powerful program with a poorly designed user interface has
little value.
Graphical user interfaces (GUIs) that use
windows,
icons, and pop-up menus have become
standard on
personal computers.
-
What is UTP? (back to
FAQ |
ABC's)
Unshielded twisted
pair cable consists of one or more paires of copper
wires. The copper wires in each pair are twisted around
each other. By twisting the wires around each other, the
cable is less prone to interference from other electrical
signals, such as the signals emitted by photocopiers or
alarm systems.
-
What is Virtual Server?
(back to FAQ |
ABC's)
A
server, usually a Web
server, that shares computer
resources with other virtual servers. In this
context, the virtual part simply means that it is not a
dedicated server -- that is, the entire
computer is not dedicated to running the server software.
Virtual Web servers are a very
popular way of providing low-cost web
hosting services. Instead of requiring a
separate computer for each server, dozens of virtual
servers can co-reside on the same computer. In most cases,
performance is not affected and each web
site behaves as if it is being served by a
dedicated server. However, if too many virtual servers
reside on the same computer, or if one virtual server
starts hogging resources, Web
pages will be delivered more slowly.
-
What is VPN? (back to
FAQ |
ABC's)
Short for virtual
private network, a
network that is constructed by using public
wires to connect nodes. For example, there are a number of
systems that enable you to create networks using the
Internet as the medium for transporting data.
These systems use
encryption and other
security mechanisms to ensure that only
authorized users can access the network and
that the data cannot be intercepted.
-
What is WAN? (back to
FAQ |
ABC's)
It stands for wide
area network. It is a
computer
network that spans a relatively large
geographical area. Typically, a WAN consists of two or
more
local-area networks (LANs).
-
What is WECA (WiFi
Alliance)? (back to
FAQ |
ABC's)
Wireless Ethernet
Compatibility Alliance, an organization made up of leading
wireless equipment and software providers with the mission
of guaranteeing interoperability of Wi-Fi products and to
promote Wi-Fi as the global wireless LAN standard across
all markets. WECA recently changed their name to WiFi
Alliance.
-
What is WEP?
(back to FAQ |
ABC's)
The whole name is
called Wireless Equivalent Privacy, which is the method by
which WLANs protect wireless data streams. a wireless
network is inherently less secure than a wired one because
it eliminates many of the physical barriers to network
access. The way WEP attempts to overcome this is by
encrypting the data transferred between two wireless
devices.
-
What is WLAN? (back to
FAQ |
ABC's)
Acronym for
wireless local-area network. Also referred to as LAWN. A
type of
local-area network that uses high-frequency
radio waves rather than wires to communicate between
nodes.
-
What is WPA? (back to
FAQ |
ABC's)
The whole name is
Wi-Fi Protected Access (WPA), and is designed to take the
place of WEP and address many of its shortcomings.
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