Hidden Connections


Doing business in the Bay Area since 1985!

COMPUTER AND NETWORKING GLOSSARY

Definitions presented in a basic way to help the average user gain a better idea of how things work.

10Base-T - refers to a maximum network transmission speed of 10,000,000 bits per second (10Mbps). Sometimes referred to as ethernet.

100Base-T - refers to a maximum network transmission speed of 100,000,000 bits per second (100Mbps). Sometimes referred to as fast ethernet.

1000Base-T - refers to a maximum network transmission speed of 1,000,000,000 bits per second (1,000Mbps). Sometimes referred to as gigabit ethernet.

auto-sensing - the ability of a hub or switch to automatically determine the maximum speed that it can communicate to a device that is connected to one of its ports

auto-switching - the ability of a hub or switch to change speeds on any one of its ports to match the maximum speed of a connected device

bit - the smallest unit of computing. One-eighth of a byte

broadband - refers to any internet connection faster than Dial-Up (Cable, DSL, ISDN, Satellite, T1/T3, etc.)

bus topology - a network connection scheme, usually employing coaxial cable where all the computers are connected in series and has terminators at each end.

byte - a basic unit of computers, a single letter, such as "A", is one byte, or eight bits

Cable - a way to connect to the internet, usually provided by the local TV cable company, with a maximum connect speed of 27,000,000 bits per second (27Mbps). Nodes connected in this fashion can be assigned a static or dynamic IP address.

Category 3 cable (Cat3) - a twisted pair cable (see UTP or STP) with a maximum transmission speed of 16MHz/10,000,000 bits per second (10Mbps). Two of the four pairs of wires in the cable are used, one pair to transmit, one pair to receive. Not used in new network installations any longer. May be used for phone systems.

Category 4 cable (Cat4) - a twisted pair cable (see UTP or STP) with a maximum transmission speed of 20MHz/16,000,000 bits per second (16Mbps). Two of the four pairs of wires in the cable are used, one pair to transmit, one pair to receive. Not used in new network installations any longer.

Category 5 cable (Cat5) - a twisted pair cable (see UTP or STP) with a maximum transmission speed of 100MHz/1,000,000,000 bits per second (1,000Mbps). Two of the four pairs of wires in the cable are used, one pair to transmit, one pair to receive.

Category 5e cable (Cat5e) - a twisted pair cable (see UTP or STP) with a maximum transmission speed of 100MHz/1,000,000,000 bits per second (1,000Mbps). All four pairs are used to simultaneously transmit and receive data.

Category 6 cable (Cat6) - a twisted pair cable (see UTP or STP) with a maximum transmission speed of 250MHz/10,000,000,000 bits per second (10,000Mbps). All four pairs are used to simultaneously transmit and receive data.

Category 7 cable (Cat7) - a shielded twisted pair cable (see STP) with a maximum transmission speed of 600MHz/10,000,000,000 bits per second (10,000Mbps). All four pairs are used to simultaneously transmit and receive data. Primarily used in Europe and specialized testing cables.

client - refers to a computer that is reliant upon another computer for some kind of data or service (files, printer, internet)

client/server - refers to a network relationship where an actual server and clients exist, as opposed to peer/peer

CO - Central Office. Refers to the telephone companies physical location where the local area's DSL lines run to.

coaxial cable - for computer cabling, this is RG-59. It has a maximum transmission rate of 10,000,000 bits per second (10Mbps). Used in a bus topology network. It is not installed as new cabling any longer.

collisions - refers to what happens when two data packets arrive at the same destination at the same time. In an ethernet network, the two sending nodes "back off" for a random number of milliseconds and then re-transmit -- hopefully at different times.

DHCP - Dynamic Host Control Protocol. A method where a server assigns an IP address to a node when the node logs onto a network. The IP address may be different every time a node logs on. This is an almost perfect setup for people that travel with laptops.

Dial-Up - refers to a connection to the internet that is done with a modem. Nodes or LAN's connected in this fashion are assigned a dynamic IP address.

DirecWay [DirecPC Two-Way] - a satellite hook-up to the internet that allows the flow of data to and from the internet through the satellite dish, thereby obviating the need for a modem. Speeds can approach those of DSL, around 1.5Mbps, although they are generally much slower, and subject to any number of man-made and enviromental factors.

DMARC - demarcation. Refers to the place in your home or business that still belongs to the phone company - where the phone lines run from the pole.

DNS - Domain Name Server. This is a special group of computers on the internet that perform name resolution.

DSL - Digital Subscriber Line. A connection to the internet, either by the telephone company or using leased lines from the telephone company, using standard phone lines at a frequency well above human hearing. Maximum speed is approximately 7,000,000 bits per second (7Mbps) although the average is 1,500,000 bits per second (1.5Mbps). Is distance limited from the CO to a maximum of 22,000 feet (4 miles). Nodes connected in this fashion are assigned either a static or dynamic IP address. "aDSL" refers to asymetrical - the sending and receiving data speeds are different. "sDSL" is symmetrical where the send and receive speeds are the same.

e-mail - private messaging over the internet. Uses SMTP and POP3 servers to move the traffic. A small program (called a client) is used to get and send mail.

ethernet - refers to a total network concept that includes a particular type of cabling (UTP or STP), NIC's, switches, hubs, the way data is transmitted, the way the network handles collisions, etc. Also used to refer to 10Base-T devices in general.

fast ethernet - see ethernet, also refers to 100Base-T devices in general.

firewall - a device to keep unwanted people from accessing the TCP/IP devices in your LAN. Can be configured to allowed specific types of public access to your LAN, such as a web server, by opening certain ports (TCP/IP).

FTP - File Transfer Protocol. A means to transmit binary (non-text) data over the internet. Much more efficient than doing the same thing with HTTP. Usually requires a small program (also referred to as a client).

gateway - refers a device that sits between your LAN and the internet. The data that is destined from the LAN to the internet (or vice versa) goes through the gateway. This may be a router or a computer running a proxy server.

gigabit ethernet - see ethernet, also refers to 1000Base-T devices in general.

HTTP - Hyper Text Transfer Protocol. The way HTML (Hyper Text Mark-Up Language) - web pages - are sent over the internet and defines the way that they will displayed in your web browser.

hub - a central connection point in a star topology network. This is a broadcast device where all transmitted data is send to all nodes. Can be very inefficient and cause excessive collisions when a lot of data is being sent over the network. It is referred to by the number of ports it has ("an 8 port hub") and can be auto-sensing and auto-switching.

IP address - a unique identifier for a node in an TCP/IP based network. This is a number composed of four sets of numbers (0-255) separated by periods, e.g.: 192.168.168.2. IP addresses on the internet can either be static - permanently assigned to a particular hardware device (such as a NIC inside a computer or print server) - or dynamic, which changes with every log on to the internet service (which is issued from a DHCP server). There are Class A (192.0.0.0 - 192.255.255.255), Class B (192.192.0.0 - 192.192.255.255), and Class C (192.192.192.0 - 192.192.192.255) type IP networks, which can be broken down even further by subnetting.

IRC - Internet Relay Chat. Real-time chatting with other people on the internet. Requires a small program (called a client) in order to do this. AOL Instant Messenger and ICQ do much the same thing, but came much later.

ISDN - Integrated Services Digital Network. A broadband connection to the internet that can achieve speeds of 128,000 bits per second (128kbps). Uses a modified telephone line.

LAN - Local Area Network. Refers to the actual network equipment and cabling within the walls of your business or home.

MODEM - MOdulator - DEModulator. A device that converts the digital data from your computer to an analog signal that is then transmitted over standard phones lines at a standard frequency. At the other end, a modem changes the analog signal back into a digital signal. Modems are rated as fast as 56,000 bits per second (56kbps) although the FCC limits this to 53kbps. Faster modems are highly susceptible to "line noise" which can severely reduce a modem's speed.

modem (DSL or Cable) - this referes to the connection device to the internet, but one which is not an actual modem as does not preform any modulation in the same sense of a Dial-Up modem.

name resolution - the process in which an URL is converted to an IP address. This is necessary because computers (except for the DNS servers) do not know how to handle the names that we humans use (http://www.hiddenconnections.net for instance).

NAT - Network Address Translation. A means where a LAN using non-routable IP addresses can communicate with the internet through (usually) a single public (static or dynamic) IP address. Can be done with a proxy server or a router that supports NAT.

newsgroups - public messaging forums. Uses a small program (called a client) to read and post messages. Uses NNTP.

network - an all-inclusive term used to describe the entirety of a computer communication set up. Includes the hardware, protocol(s), cabling, software, etc.

NIC - Network Interface Card. The device found in computers and some other devices (such as printers) that allows then to connect to the LAN. Commonly referred to as "network card" or "network adapter".

NNTP - Network News Transport Protocol. Refers to the protocol that allows for public messaging on newsgroups.

node - a single device on the network that has its own "identity" or IP address. This can be a computer, printer, router, etc.

Packet - refers to the smallest "unit" of data that travels over the network. A standard ethernet packet is 1,500 bits. Most (but not all) internet packets are 576 bits. Therefore, a single ethernet packet will have to be broken up into 3 packets (of 576, 576, and 348 bits in order to set over the internet). Packet loss refers to the condition that can exist when one, or more, packet(s) of a group that comprises a "block" of data gets lost in transmission -- the entire "block" of data must then be retransmitted -- thereby lowering QoS.

PC - Personal Computer. These days it refers to computers using an Intel based microprocessor and, most likely, Microsoft Windows.

PCMCIA - Personal Computer Memory Card International Association. Also referred to as a "PCcard". A device, primarily used in laptop or notebook computers, to add a capability. E.g.: a NIC, modem, SCSI adapter, etc.

peer/peer - refers to a network relationship where no actual server exists (although there may be a computer acting in the role as a server -- usually referred to as "server", in quotes), as opposed to client/server

POP3 - Post Office Protocol v3. A server on the internet where e-mail is stored until requested by the computer for which it is destined.

port (hub/switch) - refers to an actual RJ-45 jack on either a hub or a switch.

port (TCP/IP) - Within the TCP/IP protocol, there are 65,535 ports. These are like doorways through which different types of data flow. These data types are other protocols which work within TCP/IP. POP3, for instance, is on port 110, SMTP is 25, HTTP is 80, FTP is 21, and so on. A firewall can (and should) be set up to block access through most ports, while perhaps leaving others open for public access.

PPPoE - Point-Point Protocol over Ethernet. An internet connection protocol that allows for a connection by DSL much in the same fashion a Dial-Up works. A dynamic IP address is assigned for the duration of the connection.

PPP - Point-Point Protocol. An internet connection protocol used when two computers, on different LANs, use the internet as an intermediary. Usually used in a VPN.

PPTP - Point-Point Tunneling Protocol. A security protocol which is a superset of PPP which adds encryption to the data being transmitted since the internet is a public place.

print server - a device that is used to connect a non-network ready printer to the network as its own node, with its own IP address.

protocol - the "language" of a network. TCP/IP, NetBEUI (Microsoft), IPX/SPX (Novell) are all examples, which do not communicate to one another. Can also be used to define a common "language" that computer(s) use to describe to each other HOW they communicate with one another and/or other things, such as security procedures.

proxy server - a piece of software that resides on a computer that acts as the intermediary between client computers and the internet. This should be a PC dedicated to this task alone. Even better, this would be installed an a server running a Network Operating System.

QoS - Quality of Service. Refers to the reliability of the network. The ability of the network as a whole to move data from one node to another with the best efficiency possible and the least amount of dropped packets would have the highest QoS rating.

ring (circle) topology - refers to a Token Ring network where all of the nodes are connected in series, in a circle

router - a device that routes information between networks. E.g.: between a LAN and the internet. Certain models can perform DHCP and NAT functions.

Satellite - an internet connections that uses satellites to move data. DirecPC (Hughes) receives data from the satellite dish and transmits data through a modem. StarBand uses the satellite disk to send and receive data. Users connected in this fashion are usually assigned a dynamic IP address.

server - a computer dedicated to offering data or services to clients on a network. It uses a Network Operating System, unlike the client computers, which is especially designed to handle large amount of network requests. It also, normally, manages user log ons to the network.

sharing - the ability to allow access of data and/or printers on one or more computer(s) by other computers on the network

SMTP - Simple Mail Transfer Protocol. Defines a server that accepts outbound e-mail from a computer, then sends the mail to its destination.

star topology - the most common network type. Refers to a scheme where all devices are connected to a central point, such as a hub or switch.

STP - shielded twisted pair. A category 3, 4, 5, 5e, 6 or 7 cable that has 8 wires (4 pairs) where each pair is twisted around its mate. Has shielding to block out unwanted signals - which is usually unnecessary.

switch - a central connection device in a star topology network. Unlike a hub, this is not a broadcast device. This device routes the data to the intended destination. This decreases network chatter and increases efficiency and therefore apparent speed. It has much better QoS than a switch. It is referred to by the number of ports it has ("24 port switch") and can be auto-sensing and auto-switching.

subnet - a way to break a large network into smaller, independent, pieces.

subnet mask - an IP address that determines what subnet a node will be in. 255.0.0.0 will include all address available in a Class A IP network. 255.255.255.249, for instance, would be a subnet of a Class C network and would allow only 5 IP address to be assigned.

T1/T3 - T1 is a connection to the internet (or one which connections two or more LANs together to make a WAN) that is about 2,000,000 bits per second (2Mbps). T3 is about 34Mbps. Both have a VERY high reliability rate.

TCP/IP - Transmission Control Protocol / Internet Protocol. The underlying "language" of the internet. Also preferable for most LANs.

URL - Universal Resource Locator. What you type into you web browser or FTP client to get to that site. E.g.: http://www.hiddenconnections.net or ftp://ftp.cdrom.com

UTP - unshielded twisted pair. A category 3, 4, 5, 5e, or 6 cable that has 8 wires (4 pairs) where each pair is twisted around it mate.

VPN - Virtual Private Network(ing). A term used to describe the use of the internet by two of more nodes as a private network. Relies heavily on PPP and PPTP protocols.

WAN - Wide Area Network. Refers to two LANs that are connected to one another either by a dedicated line, or a VPN. Routers are used to move data between the two LANs.

web - the part of the internet, accessed through a web browsers, that is accessed via HTTP

WWW - World Wide Web. Part of a URL.





Last updated: September 4, 2009



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