BPS (Bits-Per-Second) The speed at which data is transmitted in bits-per-second.
A 28.8 modem can move 28,800 bits per second.
Browser A program that is used to look at various kinds of Internet resources.
In the course of tracing intrusion attempts you will sooner or later encounter a
country code. The country code is a two-letter tag at the end of a site URL
which identifies the country where the site is located. See the on-line help for
a detailed list of country codes.
Domain Name System/Server (DNS) The Domain Name System simplifies Internet navigation. Computers on the
Internet can only be found at their numerical IP address (e.g., 220.127.116.11).
An address like "somerspoint.org" makes sense to a human but a DNS
server must match it up to its IP address. The DNS server databases are updated
regularly as new domain names are registered.
Domain Name An Internet site's unique name, which can consist of two or more parts
separated by dots (sirbranch.com, jifit.com,
DSL DSL or Digital Subscriber Line is an increasingly popular method of
connecting to the Internet over regular phone lines. DSL offers the advantage of
a relatively high speed connection at prices substantially lower than ISDN
connections. In theory DSN has a download speed limit of 9 megabits per second
and an upload limit of 640 kilobits per second. In reality, and dependent of
your provider's equipment as well as your system equipment, you can expect
anything from about 1.5 megabit download/128 kilobit upload (Asymmetric DSL) to
384 kilobits in both directions (Symmetric DSL).
Electronic Mail, messages sent via the Internet or within a company LAN or WAN.
E-mail attachments in the form of EXE (executable) files or VBS (Visual Basic
script) files have become increasingly popular as a means of transmitting
viruses and Trojans.
Firewall Hardware and/or software designed to keep unauthorized outsiders from
tampering with a computer system. That system may be a standalone computer, a
small LAN or a company-wide network or WAN with thousands of users.
HTTP Hypertext Transfer Protocol moves hypertext (HTML) files on the Internet
from the server you are visiting to the browser you are viewing with.
Internet The Internet consists of a huge number of inter-connected networks that use
the TCP/IP protocols for the location and transfer of data. The Internet evolved
from a linking of university and college computers (in the late 1960s and early
1970s) funded by the U.S. Department of Defense and called the ARPANET. The
Internet today is a global network of almost 100,000 independent networks.
Intranet A private network, usually inside an organization, that functions very much
like the Internet. It has become common practice to permit access to such
Intranets from standalone computers used by students or employees off-campus or
off-site. Firewalls, login procedures and passwords are designed to provide
IP Number The Internet Protocol Number or IP address is a unique number consisting of
four parts separated by dots (e.g. 18.104.22.168). Every computer of the Internet
from the largest server to a laptop communicating through a cell phone has a
unique IP number. Not every computer has a domain name but every computer uses
ISP Internet Service Provider. This is the service you subscribe to in order to
connect with the Internet. It may be a small local company with a few thousand
subscribers, a regional company (e.g. uswest.net) or a nationwide mega-provider
like AOL or AT&T WorldNet. Most ISPs sell a connection, nothing more.
LAN Local Area Network. Two or more computers that are linked together and able
to share programs, data and/or peripherals
Modem MOdulator/DEModulator. Your modem takes data you are sending and modulates
it so that it can be transmitted over an analog voice phone line. Your modem
accepts incoming modulated data and demodulates it so that it is usable by your
computer. The earliest modems required the user to place the telephone handset
into a cradle with padded apertures for the two ends of the handset. Speeds were
in the range of 300 to 1,200 BPS. With improvements in error correction, modems
today under ideal conditions can transmit data at over 50,000 BPS. over a single
phone line. DSL and ISDN connections offer even higher speeds. These days the
term modem is frequently used to describe external network connection devices
that don't actually perform any modulation or demodulation, such as DSL and
Cable modems which are actually digital end-to-end.
NAT (Network Address Translator)
A NAT is logically similar to both a proxy and a gateway. The NAT hides the
private addresses of the local network from the public address side attached to
the Internet. The NAT takes packets from the private network and re-writes them
using one of its public IP addresses and sends it onto the public network
(Internet). When the response to the packet comes back the NAT takes this
inbound packet and redirects it to the private address that originated the
traffic. NATs allow large groups of computers to access the Internet through a
very small number of IP addresses. Without NAT technology the supply of IP
addresses would have run dry in the late 1990's. The Internet Connection Sharing
built into Windows 98SE and later is a NAT.
Network When you connect two or more computers, you create a network. When you
connect two or more networks you create an internet (lower case "i").
Node A single computer connected to a network. Nodes simply serve as connection
points in passing along data.
See 'Private IP Space'
Packet Switching This is the method used to move data on the Internet. The data you are
sending or receiving is broken up into pieces, each piece carrying the IP
address of where it is going and where it is coming from. Billions of these
pieces are passing through the Internet at any given time and the major node
servers are sorting these pieces and routing them at incredible speeds. The
E-mail you are reading or the web page you are looking at has been reassembled
and delivered to your monitor after traveling across town or around the world
and, best of all, you don't have to give it a moments thought.
PING Packet Internet Groper is a program used to determine whether a specific IP
address is accessible. A packet is sent to the specified address and the program
waits for a reply. Programs use PING to identify and/or troubleshoot Internet
connections. In addition to identifying the target site, these programs also
note all of the nodes the data passed through between the two ends of the
Private IP Space
Also known as non-routable IP address space. There are three block of IP
addresses which are reserved for private networks. These IP addresses are used
only on private networks, and cannot be connected directly to the public
Internet. If a non-routable IP address is used on a computer connected to the
Internet it must gateway through a NAT. The private IP blocks are:
10.0.0.0 through 10.255.255.255
(Any IP Address starting with 10.)
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
Proxies are used as intermediaries in connections to the Internet. They are
generally only useful for common application uses such as web browsing. Proxies
offer several benefits. They are able to cache page content locally; reducing
Internet bound traffic as well as local response time. They offer some security
benefits by isolating the local network from direct contact with the Internet.
They also offer local ability to restrict access to the Internet in general.
Proxies do have many limitations, one of which is that they cannot handle ICMP
traffic. For small networks a NAT is a superior solution to a proxy.
Server A computer or software that provides specific services to software running
on other computers. The "mail server" at your ISP is software that
handles all of the incoming and outgoing mail for all of your ISP's users. A
server on a LAN is hardware that constitutes the primary node on the network. It
may also have software which provides specific services, data or other
capabilities to all of the client computers attached to it.
TCP/IP Transmission Control Protocol/Internet Protocol, the protocols that make the
Internet possible and that make it possible for your computer to be part of the
URL Uniform Resource Locator, the standard format for Internet addresses.
WAN Wide Area Network, a network of computers that covers an area larger than a
single building or campus. In the past WANs have been private networks
connecting geographically separated offices of the same organization. WANs are
rapidly being replaced by the Internet and the wide use of VPNs.
WWW The World Wide Web or just "The Web." Many people think of this in
terms of what is accessible to their browser but in reality the web now
encompasses all of the resources that make up the Internet including such things
as FTP sites, USENET, and much more.