HP OfficeConnect Firewall Series Manuel d'utilisateur télécharger pdf (Page 146)

Appendix 21. SAFETY INFORMATION OfficeConnect VPN Firewall User’s Manual

132

requested domain name to find its corresponding IP

address. If the DNS server cannot find the IP address, it

communicates with higher-level DNS servers to

determine the IP address. See also domain name.

domain name A domain name is a user-friendly name used in place of its

associated IP address. For example, www.3com.com is

the domain name associated with IP address

192.136.34.41. Domain names must be unique; their

assignment is controlled by the Internet Corporation for

Assigned Names and Numbers (ICANN). Domain names

are a key element of URLs, which identify a specific file at

a web site, e.g., http://www.3com.com. See also DNS.

download To transfer data in the downstream direction, i.e., from the

Internet to the user.

DSL Digital Subscriber Line

A technology that allows both digital data and analog

voice signals to travel over existing copper telephone

lines.

Ethernet The most commonly installed computer network

technology, usually using twisted pair wiring. Ethernet

data rates are 10 Mbps and 100 Mbps. See also

10BASE-T, 100BASE-T, twisted pair.

filtering To screen out selected types of data, based on filtering

rules. Filtering can be applied in one direction (upstream

or downstream), or in both directions.

filtering rule A rule that specifies what kinds of data the a routing device

will accept and/or reject. Filtering rules are defined to

operate on an interface (or multiple interfaces) and in a

particular direction (upstream, downstream, or both).

firewall Any method of protecting a computer or LAN connected to

the Internet from intrusion or attack from the outside.

Some firewall protection can be provided by packet

filtering and Network Address Translation services.

FTP File Transfer Protocol

A program used to transfer files between computers

connected to the Internet. Common uses include

uploading new or updated files to a web server, and

downloading files from a web server.

hop When you send data through the Internet, it is sent first

from your computer to a router, and then from one router

to another until it finally reaches a router that is directly

connected to the recipient. Each individual ―leg‖ of the

data’s journey is called a hop.

hop count The number of hops that data has taken on its route to its

destination. Alternatively, the maximum number of hops

that a packet is allowed to take before being discarded

(see also TTL).

host A device (usually a computer) connected to a network.

HTTP Hyper-Text Transfer Protocol

HTTP is the main protocol used to transfer data from web

sites so that it can be displayed by web browsers. See

also web browser, web site.

ICMP Internet Control Message Protocol

An Internet protocol used to report errors and other

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HP OfficeConnect Firewall Series Manuel d'utilisateur Page 146

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