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Glossary
default route
The static routing table entry used to direct frames whose
next hop is not spelled out in the dynamic routing table.
delay
The time elapsed between a sender's initiation of a transaction and
the first response they receive. Also, the time needed to move a packet from
its source to its destination over a path. See also: latency.
demarc
The demarcation point between the customer premises equipment
(CPE) and the telco's carrier equipment.
demodulation
A series of steps that return a modulated signal to its orig-
inal form. When receiving, a modem demodulates an analog signal to its
original digital form (and, conversely, modulates the digital data it sends into
an analog signal). See also: modulation.
demultiplexing
The process of converting a single multiplex signal, com-
prising more than one input stream, back into separate output streams. See
also: multiplexing.
denial-of-service attack
A denial-of-service attack, or DoS, blocks access
to a network resource by saturating the device with attacking data. Typi-
cally, this is targeted against the link (particularly lower bandwidth links) or
the server. DDoS attacks, or distributed denial-of-service attacks, make use
of multiple originating attacking resources to saturate a more capable
resource.
designated bridge
In the process of forwarding a frame from a segment
to the route bridge, the bridge with the lowest path cost.
designated port
Used with the Spanning Tree Protocol (STP) to designate
forwarding ports. If there are multiple links to the same network, STP will
shut a port down to stop network loops.
designated router
An OSPF router that creates LSAs for a multiaccess
network and is required to perform other special tasks in OSPF operations.
Multiaccess OSPF networks that maintain a minimum of two attached
routers identify one router that is chosen by the OSPF Hello protocol, which
makes possible a decrease in the number of adjacencies necessary on a mul-
tiaccess network. This in turn reduces the quantity of routing protocol traffic
and the physical size of the database.
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