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800-12005V1 - A - 08/2012
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Glossary A
This appendix provides an explanation for commonly used terms in this guide.
DDNS: (Dynamic DNS) A method, protocol, or network service that provides the capability for
a networked device, such as a router or computer system using the Internet Protocol Suite, to
notify a domain name server to change, in real time the active DNS configuration of its
configured host names, addresses, or other information stored in DNS.
DHCP: (Dynamic Host Configuration Protocol) A network application protocol used by
devices (DHCP clients) to obtain configuration information for operation in an Internet Protocol
network.
Dual Stream: Dual stream is a technology used to record high resolution video locally while
transmitting a lower resolution stream over the network. The two streams are generated by the
DVR, with the main stream having a maximum resolution of 4CIF and the sub-stream having a
maximum resolution of CIF.
DVR: (Digital Video Recorder) A DVR is device that is able to accept video signals from analog
cameras, compress the signal and store it on its hard drives.
HDD: (Hard Disk Drive) A storage medium which stores digitally encoded data on platters with
magnetic surfaces.
HTTP: (Hypertext Transfer Protocol) A protocol to transfer hypertext request and information
between servers and browsers over a network
Hybrid DVR: A hybrid DVR is a combination of a DVR and NVR.
NTP: (Network Time Protocol) A protocol designed to synchronize the clocks of computers
over a network.
NTSC: (National Television System Committee) NTSC is an analog television standard used
in such countries as the United States and Japan. Each frame of an NTSC signal contains 525
scan lines at 60Hz.
NVR: (Network Video Recorder) An NVR can be a PC-based or embedded system used for
centralized management and storage for IP cameras, IP Domes and other DVRs.
PAL: (Phase Alternating Line) PAL is also another video standard used in broadcast televisions
systems in large parts of the world. PAL signal contains 625 scan lines at 50Hz.
PTZ: (Pan, Tilt, Zoom) PTZ cameras are motor driven systems that allow the camera to pan
left and right, tilt up and down and zoom in and out.
USB: (Universal Serial Bus) USB is a plug-and-play serial bus standard to interface devices to
a host computer.