NETWORK+ Terms D's Flashcards
In a frame, the field or section that contains the data.
Data field
Layer 2 of the OSI model, which is above the physical layer. Data comes off the cable, goes
through the physical layer, and goes into the data link layer. The ___ ___ layer has two distinct sublayers: MAC and LLC.
data link layer
An information grouping transmitted as a unit at the network layer.
datagram
A 25-pin connector used for serial port or parallel port connection between PCs and peripheral devices.
DB-25
A nine-pin connector used
for serial port or parallel port connection
between PCs and peripheral
devices.
DB-9
The channel used on ISDN to communicate signaling and other related information.
Use of the ____ ____ leaves the B channels free for data communication. See also B (bearer) channel.
D (delta) channel
A form of DNS that enables systems to be registered and deregistered with DNS dynamically___ ___ ___ ___ is facilitated by DHCP, which passes IP address assignments
to the DNS server for entry into the DNS server records. This is in contrast with the conventional DNS system, in which entries must be manually made.
DDNS (Dynamic Domain Name
Service)
A DoS attack that utilizes more than
one computer in the attack.
DDoS (Distributed Denial of Service)
A format for storing computer data on a
DAT. ___ ___ ___ -formatted tapes can be
read by either a this or a DAT drive.
The original one of these is standard specified a 4mm tape cartridge with a capacity of 1.3GB. Subsequent implementations of DDS have taken the capacity to 40GB with compression.
DDS (digital data storage)
A dedicated circuit used in WANs to provide a constant connection between two points.
dedicated line
Normally a router or a multihomed computer to which packets are sent when they
are destined for a host on a different
network.
default gateway
The point at which communication lines enter a customer’s premises. Sometimes shortened to simply demarc.
demarcation point
The network address to which data is sent
destination address
A protocol that provides dynamic IP addressing to ___ ___ ___ protocol enabled workstations on the network.
DHCP (Dynamic Host Configuration
Protocol)
Refers to the connection of a remote node to a network using POTS.
dialup networking
A backup of only the data that has been created or changed since the previous full
backup. In a ____ ____, the state of the archive bits is not altered.
differential backup
On a Linux, UNIX, or Macintosh system, you can use the ____ command to perform manual DNS lookups.
dig
A system that enables network resources to be viewed as objects stored in a database.
This database can then be divided and distributed among different servers on the network. Examples of ___ ___ systems include Novell Directory Services and Microsoft Active Directory.
directory services
A plan for implementing duplicate computer
services if a natural disaster, a human-made disaster, or another catastrophe occurs. A ___ ___ ___ includes offsite backups and procedures to activate information systems in alternative locations.
disaster recovery plan
A fault-tolerant standard based on RAID 1 that uses disk mirroring with dual disk controllers.
disk duplexing
A fault-tolerant standard that is defined as RAID 1 and mirrors data between two disks
to create an exact copy.
disk mirroring
An implementation of RAID in which data is distributed across multiple disks in a stripe.
Some striping implementations provide
performance improvements (RAID 0), whereas others provide fault tolerance (RAID 5).
disk striping
A type of routing in which a router uses
broadcasts to inform neighboring routers on the network of the routes it knows about. Compare with linkstate routing.
distance-vector routing
The service provided by the data link layer of
the OSI model.
DLC (Data Link Control)
An area for placing web and other servers
that serve the general public outside
the firewall, therefore isolating them
from internal network access.
DMZ (Demilitarized Zone)
A system used to translate domain
names, such as www.quepublishing.com, into IP addresses, such as 165.193.123.44.
___ ___ ___ uses a hierarchical namespace that enables the database of hostname-to-IP address mappings to be distributed across multiple servers.
DNS (Domain Name Service)
A telecommunications standard for
transmitting high-speed data over
existing cable TV systems.
DOCSIS (Data-Over-Cable Service
Interface Specification)
A logical boundary of an Active Directory Structure on Windows servers. Also, a section of the DNS namespace.
domain
A server that runs application software that
enables the server to perform a role
associated with this service.
domain name server
A type of hacking attack in which the target system is overwhelmed with requests for service, which keeps it from servicing any requests—legitimate or otherwise.
DoS (denial of service) attack
A period of time during which a computer system or network is unavailable. This may be
due to scheduled maintenance or
hardware or software failure.
downtime
A public network technology that
delivers high bandwidth over conventional
copper wiring over limited
distances.
DSL (Digital Subscriber Line)
A network communications device that formats and controls data for transmission
over digital lines. A DSU is used
with a CSU.
DSU (data service unit)
A device used at the user end of a user network interface that serves as a data source, a destination, or both. \_\_\_ \_\_\_ \_\_\_ devices include computers, protocol translators, and multiplexers.
DTE (data terminal equipment)
A keyboard/monitor combination that enables access to a multiuser system but provides
no processing or storage at the local
level.
dumb terminal
In RAID, a RAID 1 mirror set in which each drive is connected to a separate controller to
eliminate the single point of failure
that the controller created.
duplexing
A form of multiplexing optical signals that replaces SONET/SDH regenerators with
erbium doped fiber amplifiers (EDFAs) and can also amplify the signal and allow it to travel a greater distance. The main components of a ___ ___ ___ ___ system include a terminal multiplexer, line repeaters, and a
terminal demultiplexer.
DWDM (Dense Wavelength Division
Multiplexing)
A routing system that enables routing information to be communicated between devices 618 DLC (Data Link Control) automatically and that can recognize changes in the network topology and update routing tables accordingly. Compare with static routing.
dynamic routing
A flow control mechanism that prevents the sender of data from overwhelming the
receiver. The amount of data that
can be buffered in a ___ ___
varies in size, hence its name.
dynamic window
