Chapter_5

Question 1

Dr?

Answer 1

designated router

Question 2

BDR?

Answer 2

back-up designated router

Question 3

default route? static

Answer 3

Default routes are used to send traffic to any destination beyond the next upstream router.

Question 4

LSA?

Answer 4

link state advertisement

Question 5

multicast address (all ospf routers) is what number?

Answer 5

224.0.0.5

Question 6

224.0.0.6 is used for what in ospf?

Answer 6

a multicast address in ospf used to send LSA (link state advertisements) to the designated router and BDR from the DRother (other routers) in the network. multicast address 224.0.0.6 (all DR routers

Question 7

how is a DR chosen?

Answer 7

based on the router with the highest interface priority. (0-255) default is 1. *if the interface priority is -= then the router with the highest router id is chosen.

Question 8

uses multicast 224.0.0.5 to listen to LSA’s? which router? DR, BDR, or DRother?

Answer 8

DRother. listens to or receives multicast address (all ospf enabled routers)

Question 9

uses multicast 224.0.0.6 to send LSA’s? DR, BDR, DRother?

Answer 9

DRother used this address to send LSA’s to the DR and BDR.

Question 10

what is the ASBR?

Answer 10

ASBR: autonomous system boundary router: the router located between the ospf and non ospf networks.

Question 11

what does the following command do? show ip route

Answer 11

displays the routes and how they were learned (OSPF, etc.).

Question 12

if i use the ‘show ip route’ command and i see the following then what does it mean? * asterics, E1 or E2?

Answer 12

• asterics: the connection is a good candidate for the default route.
  E1: tells u the route is the external route and the cost (metric) of the route is the addition of the internal and external cost to reach that route. (preferred)
  E2: the cost of the external route.

Question 13

the command: ipv6 route ::/0 (ipv6 address of exit interface) is used for what and does what?

Answer 13

sets the default static route (exit interface connects to isp ipv6 address) on the edge router and this router uses OSPF to tell and update all other routers once the : default-information originate info is programmed.

Question 14

what does the command do:? # show ipv6 route static

Answer 14

displays the default static route - this is shown as:

S ::/0 (interface) via (ipv6 address of ISP)

Question 15

what does the command do:
#show ipv6 route ospf

Answer 15

displays the ospf routes on the router, the E1 or E2 tells you that the route is external and the metric of the route. IPV6 does not use a * symbol telling you if the route is a good candidate for the default route like 1pv4 does.

Question 16

what does the following command do?

show ip ospf interface ‘interface number’

Answer 16

displays the serial number, hello and dead intervals.

Question 17

what does the following command do?

show ip ospf neighbor

Answer 17

displays the adjacent OSPF neighbors.

Question 18

what command is used to change/set the hello interval in ospf on a router?

Answer 18

ip ospf hello-interval (seconds)

Question 19

what command is entered on a router to change the ospf dead-interval?

Answer 19

ip ospf dead-interval (seconds)

Question 20

what commands are used to reset the ospf dead and hello intervals?

Answer 20

Use the no ip ospf hello-interval and no ip ospf dead-interval commands to reset the intervals to their default.

Question 21

what command is used in ipv6 and ipv4 to modify the hello interval?

Answer 21

ipv6 ospf hello-interval (seconds)
and
ip ospf hello-interval (seconds)

Question 22

what command is used to show a specific interface heelo, dead timer allong with the state of each adjacency as full or not.?

Answer 22

show ipv6 ospf interface ‘interface desired’ | include timer
^ displays the v6 but can also be done using:
show ip ospf interface ‘desired interface’ | include timer