You want to advertise only a default route into a new area, which will be called area 7. In this scenario, which configuration statement would solve this problem?
A.
user@host# set protocols ospf area 0.0.0.7 nssa default-lsa default-metric 10
B.
user@host# set protocols ospf area 0.0.0.7 stub no-summaries
C.
user@host# set protocols ospf area 0.0.0.7 stub default-metric 10
D.
user@host# set protocols ospf area 0.0.0.7 stub
This command configures Area 7 as a stub area and ensures that no route summarization occurs when advertising routes into the stub area, which aligns with the requirement of advertising only a default route
A: wrong because NSSA area still have Summary route, not only default route.
default-lsa—Configures the ABR to generate a default route into the NSSA.
default-metric—Specifies that the ABR generate a default route with a specified metric into the NSSA.
B: right because Area 7 will be totally stub area=> stub with optio no-summary
Watch this Youtube Video on how to configure an OSPF area to ONLY advertise a default route . Which seems to confirm that Answer B is correct as I stated before.
https://www.youtube.com/watch?v=J018-3h2lB8
# set protocols ospf area 0.0.0.7 stub no-summaries
Restrict Type3 LSA . Allow only internal routes and default route.
Converts STUB area into Totally Stub Area.
B is correct!
How is the answer A and not B.
NSSA is related to an ASBR which is External Network that utilise LSA 7. Nothing in the question states external.
Also the metric has been set and not default. You would think they would stated the metric also needs to be set to 10.
My bread and butter is Cisco, and the config for this answer in the Cisco world would be "area 7 stub no-summary" which looks exactly like Answer B.
You need the no-summary command to inject a single default route.
This question has two possible answers it seems. Based on https://www.juniper.net/documentation/en_US/junos/topics/topic-map/ospf-stub-and-not-so-stubby-areas.html
A can be correct:
"On the ABR, inject a default route into the area.
[edit protocols ospf area 0.0.0.9 nssa]
user@host# set default-lsa default-metric 10"
and C can be correct:
To quickly configure the ABR to inject a default route into the area, copy the following command and paste it into the CLI. You apply this configuration only on the ABR.
[edit] set protocols ospf area 07 stub default-metric 10
B and D can't be correct
B is optional so can't be correct
(Optional) To quickly configure the ABR to restrict all summary advertisements and allow only internal routes and default route advertisements into the area, copy the following command and paste it into the CLI. You apply this configuration only on the ABR.
[edit] set protocols ospf area 0.0.0.7 stub no-summaries
D can't be correct because it doesn't restrict to only a default route.
To quickly configure an OSPF stub area, copy the following command and paste it into the CLI. You must configure all routing devices that are part of the stub area.
[edit] set protocols ospf area 07 stub
As per
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/ospf-stub-and-not-so-stubby-areas.html
To quickly configure the ABR to inject a default route into the area, copy the following command and paste it into the CLI. You apply this configuration only on the ABR.
[edit]
set protocols ospf area 07 stub default-metric 10
A can be valid:
NSSA area - On the ABR, inject a default route into the area.
[edit protocols ospf area 0.0.0.9 nssa]user@host# set default-lsa default-metric 10
But C can also be right:
Stub area - To quickly configure the ABR to inject a default route into the area
[edit] set protocols ospf area 07 stub default-metric 10
I will go for A.
On area border routers only, for a not-so-stubby area (NSSA), inject a default link-state advertisement (LSA) with a specified metric value into the area. The default route matches any destination that is not explicitly reachable from within the area.
https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/default-lsa-edit-protocols-ospf.html
I revise my earlier answer, it is B. no-summaries is required to make an area a totally stub or totally nssa. The configuration has other issues, especially when looking at the OSPF database, but it will make the area totally stub
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