mmercial and DLC (Digital Loop Carrier) .edu for educational). Both .com and .edu are Used to economically bring fiber closer to top-level domain names. The domain name customers. Carriers run fiber cabling from can also designate the country, such as .bo for central offices to DLCs and they lay twisted- Bolivia. A domain name is part of the TCP/IP pair copper cabling from DLCs to customers. addressing convention. divestiture DoS (Denial-of-Services) attack In January 1984, Divestiture deregulated An attack by which hackers bombard net- long-distance service in the United States. works with thousands of packets intended to It separated the former AT&T from its 22 disrupt the capability of the attacked network local Bell telephone companies. Agreement to function. on Divestiture was reached by the Justice Department, which negotiated an antitrust Downlink (DL) settlement with the former AT&T, called the On broadband and mobile networks, the Modified Final Judgment. downlink portions are those that carry traffic from the carrier to the customer. DNIS (Dialed-Number Identification Service) The service used to identify and route toll- downloading free and 900 numbers to particular agents or Receiving an entire file from another loca- devices within a customer site. For example, tion. When music is downloaded, the entire if a customer has multiple 800 numbers, the music file must be downloaded to the com- network provider routes each toll-free num- puter's hard drive before it can be played. ber to a different four-digit number at the customer's telephone system. The onsite tele- DS-0 (Digital Signal level 0) phone system then routes the call to a particu- A transmission rate of 64Kbps. This refers to lar group of agents, voice response system, or one channel of a T1, E1, E3, T3, fractional department. T1, or fractional T3 circuit. Glossary DS-1 (Digital Signal level 1) The T1 transmission rate of 1.54Mbps. There The European standard for T3. E3 has a are 24 channels associated with DS-1 or T1. speed of 34.368Mbps wit