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designated router



back-up designated router


default route? static

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



link state advertisement


multicast address (all ospf routers) is what number?

6 is used for what in ospf?

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 (all DR routers


how is a DR chosen?

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.


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

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


uses multicast to send LSA's? DR, BDR, DRother?

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


what is the ASBR?

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


what does the following command do? show ip route

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


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

* 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.


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

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.


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

displays the default static route - this is shown as:
S ::/0 (interface) via (ipv6 address of ISP)


what does the command do:
#show ipv6 route ospf

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.


what does the following command do?
show ip ospf interface 'interface number'

displays the serial number, hello and dead intervals.


what does the following command do?
show ip ospf neighbor

displays the adjacent OSPF neighbors.


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

ip ospf hello-interval (seconds)


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

ip ospf dead-interval (seconds)


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

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


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

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


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

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