CCNA Vocabulary_D.txt

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CCNA Vocabulary_D.txt
2011-07-12 11:19:50
CCNA Vocab

CCNA Vocab D
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  1. daemon
    a computer program that runs in the background and is usually initiated as a process. Daemons often support server processes.
  2. data communications equipment
    the devices and connections of a communications network that comprise the network end of the user to network interface. The DCE provides a physical connection to the network, forwards traffic, and provides a clocking signal used to synchronize data transmission between DCE and DTE devices. Modems and interface cards are examples of DCE. Compare to DTE data termianl equipment devices at the user end of a user-network interface that serves as a data source, destination or both. DTE connects to a data network through a DCE device and typically uses clocking signals generated by the DCE. DTE includes such devices as computers, protocols translators, and multiplexers.
  3. decapsulation
    a process by which an end device, after it receives data over some transmission medium, examines the headers and trailers at each successive higher layer, eventually handing the data to the correct application. Sometimes called de-encapsulation.
  4. default gateway
    a device on a network that serves as an access point to other networks. A default gateway is used by a host to forward IP packets that have destination addresses outside the local subnet. A router interface typically is used as the default gateway. When the computer needs to send a packet to another subnet, it sends the packet to its default gateway.
  5. default route
    Routing table entry that is used to direct frames for which a next hop is not explicitly listed in the routing table. This route is used to forward a packet when no other known route exists for a give packet's destination address.
  6. delimiter
    this field of a frame signals the beginning or end of a frame.
  7. destination IP address
    the layer 3 address to which the data is going.
  8. deterministic
    refers to whether the performance of a device, attached to a particular type of LAN, can be accurately predicted. Token Ring LANS are deterministic, but ethernet LANS are non deterministic.
  9. digital logic
    also known as boolean algebra. These consist of the AND OR and IF operations
  10. directed broadcast
    a term that describes IPv4 packets sent to all hosts in a particular network. In a directed broadcast, a single copy of the packet is routed to the specified network, where it is broadcast to all hosts on that network
  11. directly connected network
    a network that is connected to a device's interface. For example networks that interface with the router are known to be directly connected. Devices learn their initial IP routes based on being connected to these subnets.
  12. dispersion
    the spreading of light signal caused by light signals traveling at different speeds through a fiber.
  13. distributed
    a method of computer processing in which different parts of a program run simultaneously on two or more computers that are communicating with each other over a network
  14. dns resolver
    the client part of the DNS client server mechanism. A DNS resolver creates queries sent a across a network to a same server, interprets responses, and returns information to the requesting programs.
  15. domain name
    a name, as defined by DNS that uniquely identifies a computer in the internet. DNS servers can then respond to the DNS requests by supplying the IP address that is used by the computer that has a particular domain name. This term also refers to the part of a URL that identifies a single company or organization, such as
  16. domain name system
    an internet wide system by which a hierarchical set of DNS servers collectively hold all the name IP address mappings, with DNS servers referring users to the correct DNS server to successfully resolve a DNS name.
  17. dotted decimal
    a convention for writing IP addresses with four decimal numbers, ranging from 0 to 255, with each octet representing 8 bits of the 32 bit IP address. The term originates from the fact that each of the four decimal numbers is separated by a period.
  18. download
    to transfer data from the computer functioning as a server to the client computer you are using.
  19. dynamic host configuration protocol
    a protocol used to dynamically assign IP configurations to hosts. The services defined by the protocol are used to request and assign an IP address, default gateway, and DNS server address to a network host.
  20. dynamic or private ports
    • TCP or UDP ports that range from 49152 to 65535 and are not used by any defined server applications.
    • dynamic routingrouting that adjusts automatically to network topology or traffic changes.