SAR715PV ADSL Ethernet Router User’s Guide
Chapter
17
. Appendix G Glossary
183
from a shared pool of IP addresses; after a specified time limit,
DHCP returns the address to the pool.
DHCP relay
Dynamic Host Configuration Protocol relay
A DHCP relay is a computer that forwards DHCP data between
computers that request IP addresses and the DHCP server that
assigns the addresses. Each of the SAR715PV's interfaces can
be configured as a DHCP relay.
See DHCP
.
DHCP server
Dynamic Host Configuration Protocol server
A DHCP server is a computer that is responsible for assigning IP
addresses to the computers on a LAN.
See DHCP
.
digital
Of data, having a form based on discrete values expressed as
binary numbers (0's and 1's). The data component in DSL is a
digital signal.
See also analog
.
DNS
Domain Name System
The DNS maps domain names into IP addresses. DNS
information is distributed hierarchically throughout the Internet
among computers called DNS servers. When you start to access
a web site, a DNS server looks up the 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.globespan.net is the
domain name associated with IP address 209.191.4.240.
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.globespan.net/index.html.
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.
