Glossary
The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.
Domain name
A domain name is a
Downstream
The direction of a downstream signal is from the ISP/service provider to the user's computer (downloading).
DSL
Short for Digital Subscriber Line, which is a data communications technology that transmits information over the existing copper telephone lines (POTS). DSL takes existing voice cables that connect customer premises (CPE) to the phone company's central office (CO) and turns them into a
- E -
Encapsulation
A technology that enables one network to send its data via another network's connections. Encapsulation works by encapsulating a network protocol within packets carried by the second network. Encapsulation is also called tunneling.
Ethernet
A
A newer version of Ethernet, called
- F -
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 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
A system designed to prevent unauthorized access to or from a private
120 | EN/LZT 108 6492 R2 - October 2003 |
