Chapter 21

Question 1

2-way state

Answer 1

2-way state
In OSPF, a neighbor state that implies that the router has exchanged Hellos with the neighbor and that all required parameters match.

Question 2

Area Border Router (ABR)

Answer 2

Area Border Router (ABR)
A router using OSPF in which the router has interfaces in multiple OSPF areas.

Question 3

backbone area

Answer 3

backbone area
In OSPFv2 and OSPFv3, the special area in a multiarea design, with all nonbackbone areas needing to connect to the backbone area, area 0.

Question 4

convergence

Answer 4

convergence
The time required for routing protocols to react to changes in the network, removing bad routes and adding new, better routes so that the current best routes are in all the routers’ routing tables.

Question 5

distance vector

Answer 5

distance vector
The logic behind the behavior of some interior routing protocols, such as RIP. Distance vector routing algorithms call for each router to send its entire routing table in each update, but only to its neighbors. Distance vector routing algorithms can be prone to routing loops but are computationally simpler than link-state routing algorithms.

Question 5

Dead Interval

Answer 5

In OSPF, a timer used for each neighbor. A router considers the neighbor to have failed if no Hellos are received from that neighbor in the time defined by the timer.

Question 6

designated router (DR)

Answer 6

In OSPF, on a multiaccess network, the router that wins an election and is therefore responsible for managing a streamlined process for exchanging OSPF topology information between all routers attached to that network.

Question 7

Dijkstra Shortest Path First (SPF) algorithm

Answer 7

Dijkstra Shortest Path First (SPF) algorithm
The name of the algorithm used by link-state routing protocols to analyze the LSDB and find the least-cost routes from that router to each subnet.

Question 8

full state

Answer 8

full state
In OSPF, a neighbor state that implies that the two routers have exchanged the complete (full) contents of their respective LSDBs.

Question 9

fully adjacent

Answer 9

fully adjacent
In OSPF, a characterization of the state of a neighbor in which the two neighbors have reached the full state.

Question 10

Hello Interval

Answer 10

Hello Interval
With OSPF and EIGRP, an interface timer that dictates how often the router should send Hello messages.

Question 11

interior gateway protocol (IGP)

Answer 11

interior gateway protocol (IGP)
A routing protocol designed to be used to exchange routing information inside a single autonomous system.

Question 12

link-state

Answer 12

link-state
A classification of the underlying algorithm used in some routing protocols. Link-state protocols build a detailed database that lists links (subnets) and their state (up, down), from which the best routes can then be calculated.

Question 13

internal router

Answer 13

internal router
In OSPF, a router with all interfaces in the same nonbackbone area.

Question 14

link-state advertisement (LSA)

Answer 14

link-state advertisement (LSA)
In OSPF, the name of the data structure that resides inside the LSDB and describes in detail the various components in a network, including routers and links (subnets).

Question 15

link-state database (LSDB)

Answer 15

link-state database (LSDB)
In OSPF, the data structure in RAM of a router that holds the various LSAs, with the collective LSAs representing the entire topology of the network.

Question 16

Link-State Update

Answer 16

Link-State Update
An OSPF packet used to send an LSA to a neighboring router.

Question 17

metric

Answer 17

metric
A unit of measure used by routing protocol algorithms to determine the best route for traffic to use to reach a particular destination.

Question 18

multiarea OSPF

Answer 18

multiarea OSPF
In OSPFv2 and OSPFv3, a design that uses more than one area within one OSPF domain (typically a single company).

Question 19

neighbor

Answer 19

neighbor
In routing protocols, another router with which a router decides to exchange routing information.

Question 20

routed protocol

Answer 20

routed protocol
A protocol that defines packets that can be routed by a router. Examples of routed protocols include IPv4 and IPv6.

Question 21

router ID (RID)

Answer 21

router ID (RID)
In EIGRP and OSPF, a 32-bit number, written in dotted-decimal notation, that uniquely identifies each router.

Question 22

router LSA

Answer 22

router LSA
In OSPF, a type of LSA that a router creates to describe itself and the networks connected to it.

Question 23

shortest path first (SPF) algorithm

Answer 23

shortest path first (SPF) algorithm
The name of the algorithm used by link-state routing protocols to analyze the LSDB and find the least-cost routes from that router to each subnet.

Question 24

single-area OSPF

Answer 24

single-area OSPF
In OSPFv2 and OSPFv3, a design that uses a single area within one OSPF domain (typically a single company).

Question 25

summary LSA

Answer 25

summary LSA
In OSPFv2, a type of LSA, created by an Area Border Router (ABR), to describe a subnet in one area in the database of another area.