Ccna3 Chapter 5

Front 1

Routers and Layer 3 switches learn about remote networks in one of two ways:

Back 1

Manually

Dynamically

Front 2

Manually - Remote networks are manually entered into the route table

Back 2

using static routes.

Front 3

Manual routes must be reconfigured anytime the

Back 3

network topology changes.

Front 4

Static routing has three primary uses:

Back 4

Ease of routing table maintenance

Routing to and from stub networks.

Using a single default route.

Front 5

Dynamically - Remote routes are automatically learned using a

Back 5

dynamic routing protocol.

Front 6

Dynamic routing protocols require less

Back 6

administrative overhead.

Front 7

The expense of using dynamic routing protocols is dedicating part of a router’s resources for

Back 7

protocol operation.

Front 8

Most networks use a combination of

Back 8

dynamic routing protocols and static routes.

Front 9

OSPF its features include:

Back 9

Classless

Efficient

Fast convergence

Scalable

Secure

Front 10

OSPF is classless and supports

Back 10

VLSM and CIDR.

Front 11

Routing changes trigger

Back 11

routing updates.

Front 12

It uses the SPF algorithm to choose the

Back 12

best path.

Front 13

OSPF supports this type of authentication:

Back 13

(MD5) authentication.

Front 14

OSPF defines five network types:

Back 14

Point-to-point

Broadcast multiaccess

Nonbroadcast multiaccess

Point-to-multipoint

Virtual links

Front 15

Multiaccess networks can create two challenges for OSPF regarding the flooding of LSAs:

Back 15

Creation of multiple adjacencies

Extensive flooding of LSAs

Front 16

The solution to managing the number of adjacencies and the flooding of LSAs on a multiaccess network is the

Back 16

DR.

Front 17

OSPF elects a DR to be the

Back 17

collection and distribution point for LSAs.

Front 18

A BDR is also elected in case the

Back 18

DR fails.

Front 19

If the DR stops producing Hello packets, the BDR

Back 19

promotes itself and assumes the role of DR.

Front 20

All other non-DR or BDR routers become

Back 20

DROTHER.

Front 21

Instead of flooding LSAs to all routers in the network, DROTHERs only send their LSAs to the

Back 21

DR and BDR using the multicast address 224.0.0.6.

Front 22

The router with the highest router-id is

Back 22

elected DR.

Front 23

The state of neighbors in multiaccess networks can be:

Back 23

FULL/DROTHER

FULL/DR

FULL/BDR

2-WAY/DROTHER

Front 24

The normal state for an OSPF router is usually

Back 24

FULL.

Front 25

If a router is stuck in another state, it is an indication that there are problems in

Back 25

forming adjacencies.

Front 26

Default DR/BDR Election Process:

Back 26

highest interface priority > highest router ID > highest loopback IP address > highest active IPv4 address

Front 27

The DR and BDR election process takes place as soon as the first router is

Back 27

powered on or when the OSPF network command is configured.

Front 28

After the DR is elected, it remains the DR until one of the following events occurs:

Back 28

The DR fails.

The OSPF process fails or is stopped.

The multiaccess interface fails or is shutdown.

Front 29

Instead of relying on the router ID, it is better to control the election by setting

Back 29

interface priorities.

Front 30

If the interface priority is configured after OSPF is enabled, the administrator must either:

Back 30

Shut down and re-enablethe OSPF process on all routers.

Shutdown and re-enable the router interfaces.

Front 31

The router located between an OSPF routing domain and a non-OSPF network is also called the

Back 31

autonomous system boundary router (ASBR).

Front 32

The (ASBR) router connected to the Internet is used to propagate a

Back 32

a default route to other routers.

Front 33

The default-information originate command

Back 33

propagate the default static route in OSPF updates.

Front 34

O*E2 signifies that a route was learned using

Back 34

OSPF and that is an external route.

Front 35

A type 1 route is the

Back 35

externel and internal cost combined and is always prefered.

Front 36

A type 2 route is the cost of the

Back 36

external route.

Front 37

The OSPF Hello and Dead intervals are configurable on a

Back 37

per-interface basis.

Front 38

The OSPF intervals must match or a

Back 38

neighbor adjacency does not occur.

Front 39

OSPF Attacks:

Back 39

disrupting routing peers.

falsifying information.

Front 40

The consequences of falsifying routing information are:

Back 40

Redirecting traffic to create routing loops.

Monitoring traffic.

Discarding traffic.

Front 41

To mitigate against routing protocol attacks, configure

Back 41

OSPF authentication.

Front 42

When neighbor authentication has been configured on a router, the router authenticates the

Back 42

source of each routing update packet that it receives.

Front 43

This is accomplished by the exchange of an

Back 43

authenticating key.

Front 44

OSPF authentication can either be:

Back 44

none (or null)

simple

Message Digest 5 (MD5)

Front 45

Simple authentication

Back 45

plaintext password exchanged between peers.

Front 46

MD5 authentication

Back 46

password is calculated using the MD5 algorithm.

Front 47

The routing message and preshared key are used to calculate a

Back 47

signature.

Front 48

The recieving router combines the message and key to determine the

Back 48

signature.