Web Hosting Glossary

A commonly discussed configuration of ADSL would allow a subscriber to receive data (download) at speeds of up to 1.544 Megabits per second, and to send (upload) data at speeds of 128 kilobits per second. Thus the 'Asymmetric' part of the acronym. Another commonly discussed configuration would be symmetrical: 384 kilobits per second in both directions. In theory ADSL allows download speeds of up to 9 megabits per second and upload speeds of up to 640 kilobits per second. ADSL is often discussed as an alternative to ISDN, allowing higher speeds in cases where the connection is always to the same place.

Source: http://www.microsoft.com/ntserver/nts/exec/overview/changed.asp

Usually a CGI program is a small program that takes data from a web server and does something with it, like putting the content of a form into an e-mail message, or turning the data into a database query. CGI "scripts" are just scripts which use CGI. CGI is often confused with Perl, which is a programming language, while CGI is an interface to the server from a particular program. Perl is an application of CGI, as well as MIVA, Python, PHP3, and other scripting languages.

Depending on the type of Cookie used, and the Browser's settings, the Browser may accept or not accept the Cookie, and may save the Cookie for either a short time or a long time. Cookies might contain information such as login or registration information, online 'shopping cart' information, user preferences, etc. When a Server receives a request from a Browser that includes a Cookie, the Server is able to use the information stored in the Cookie. For example, the Server might customize what is sent back to the user, or keep a log of particular user's requests. Cookies are usually set to expire after a predetermined amount of time and are usually saved in memory until the Browser software is closed down, at which time they may be saved to disk if their 'expire time' has not been reached. Cookies do not read your hard drive and send your life story to the CIA, but they can be used to gather more information about a user than would be possible without them.

Usually, all of the machines on a given Network will have the same thing as the right-hand portion of their Domain Names in the examples above. It is also possible for a Domain Name to exist but not be connected to an actual machine. This is often done so that a group or business can have an Internet e-mail address without having to establish a real Internet site. In these cases, some real Internet machine must handle the mail on behalf of the listed Domain Name.

'hits' are often used as a very rough measure of load on a server, e.g. 'Our server has been getting 300,000 hits per month.' Because each 'hit' can represent anything from a request for a tiny document (or even a request for a missing document) all the way to a request that requires some significant extra processing (such as a complex search request), the actual load on a machine from 1 hit is almost impossible to define.

Another sloppier use of the term refers to practically any web page as a 'homepage,' e.g. 'That web site has 65 homepages and none of them are interesting.'

As the Internet has become more popular many of the tools used on the Internet are being used in private networks, for example, many companies have web servers that are available only to employees. Note that an Intranet may not actually be an internet -- it may simply be a network.

Every machine that is on the Internet has a unique IP number - if a machine does not have an IP number, it is not really on the Internet. Most machines also have one or more Domain Names that are easier for people to remember.

We can expect to see a huge variety of features added to the Web using Java, since you can write a Java program to do almost anything a regular computer program can do, and then include that Java program in a Web page.

An email program is said to be MIME Compliant if it can both send and receive files using the MIME standard. When non-text files are sent using the MIME standard they are converted (encoded) into text - although the resulting text is not really readable. Generally speaking the MIME standard is a way of specifying both the type of file being sent (e.g. a QuicktimeÅ video file), and the method that should be used to turn it back into its original form. Besides email software, the MIME standard is also universally used by Web Servers to identify the files they are sending to Web Clients, in this way new file formats can be accommodated simply by updating the Browsers' list of pairs of MIME-Types and appropriate software for handling each type.

Another common use of the term 'mirror' refers to an arrangement where information is written to more than one hard disk simultaneously, so that if one disk fails, the computer keeps on working without losing anything.

Netscape has grown in features rapidly and is widely recognized as the best and most popular web browser. Netscape corporation also produces web server software. Netscape provided major improvements in speed and interface over other browsers, and has also engendered debate by creating new elements for the HTML language used by Web pages -- but the Netscape extensions to HTML are not universally supported. The main author of Netscape, Mark Andreessen, was hired away from the NCSA by Jim Clark, and they founded a company called Mosaic Communications and soon changed the name to Netscape Communications Corporation.

The idea behind plug-in's is that a small piece of software is loaded into memory by the larger program, adding a new feature, and that users need only install the few plug-ins that they need, out of a much larger pool of possibilities. Plug-ins are usually developed by a third party.

On the Internet port often refers to a number that is part of a URL, appearing after a colon (:) right after the domain name. Every service on an Internet server listens on a particular port number on that server. Most services have standard port numbers, e.g. Web servers normally listen on port 80. Services can also listen on non-standard ports, in which case the port number must be specified in a URL when accessing the server, so you might see a URL of the form: gopher://peg.cwis.uci.edu:7000/ shows a gopher server running on a non-standard port (the standard gopher port is 70). Finally, port also refers to translating a piece of software to bring it from one type of computer system to another, e.g. to translate a Windows program so that is will run on a Macintosh.

(Point to Point Protocol) -- Most well known as a protocol that allows a computer to use a regular telephone line and a modem to make TCP/IP connections and thus be really and truly on the Internet.

enable users of personal computers and other consumer electronic devices to send and receive audio, video and other multimedia services using the Web.

Security Certificates contain information about who it belongs to, who it was issued by, a unique serial number or other unique identification, valid dates, and an encrypted 'fingerprint' that can be used to verify the contents of the certificate. In order for an SSL connection to be created both sides must have a valid Security Certificate.

SMTP consists of a set of rules for how a program sending mail and a program receiving mail should interact. Almost all Internet email is sent and received by clients and servers using SMTP, thus if one wanted to set up an email server on the Internet one would look for email server software that supports SMTP.

A device is said to be 'SNMP compatible' if it can be monitored and/or controlled using SNMP messages. SNMP messages are known as 'PDU's' - Protocol Data Units. Devices that are SNMP compatible contain SNMP 'agent' software to receive, send, and act upon SNMP messages. Software for managing devices via SNMP are available for every kind of commonly used computer and are often bundled along with the device they are designed to manage. Some SNMP software is designed to handle a wide variety of devices.

E.g. Mary spammed 50 USENET groups by posting the same message to each.

SSL used mostly (but not exclusively) in communications between web browsers and web servers. URL's that begin with 'https' indicate that an SSL connection will be used. SSL provides 3 important things: Privacy, Authentication, and Message Integrity. In an SSL connection each side of the connection must have a Security Certificate, which each side's software sends to the other. Each side then encrypts what it sends using information from both its own and the other side's Certificate, ensuring that only the intended recipient can de-crypt it, and that the other side can be sure the data came from the place it claims to have come from, and that the message has not been tampered with.

The most common way to use a URL is to enter into a WWW browser program, such as Netscape, or Lynx.