JN0-102 · Question #306
user@router> show route inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden) + = Active Route, - = Last Active, = Both 10.10.10.91/32 [Direct/0] 00:09:40 >via lo0.0 10.10.10.92/32 [OSPF/1
The correct answer is D. 192.168.0.0/17, 192.168.50.0/24, and 192.168.51.0/24. The policy demo uses a route-filter with the longer match type, which, as implied by the correct answer, rejects routes that are strictly more specific than 192.168.0.0/16.
Question
user@router> show route inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden) + = Active Route, - = Last Active, * = Both 10.10.10.91/32 *[Direct/0] 00:09:40 >via lo0.0 10.10.10.92/32 *[OSPF/10] 00:01:50, metric 1 >to 172.16.1.2 via ge-0/0/2.0 100.100.1.0/24 *[Static/5] 00:01:50 Reject 172.16.1.0/24 *[Direct/0] 00:06:09 >via ge-0/0/2.0 172.16.1.1/32 *[Local/0] 00:06:09 Local via ge-0/0/2.0 192.168.0.0/16 *[Aggregate/130] 00:00:06 Reject 192.168.0.0/17 *[Aggregate/130] 00:00:06 >to 172.16.1.2 via ge-0/0/2.0 192.168.50.0/24 *[Static/5] 00:00:06 >to 172.16.1.2 via ge-0/0/2.0 192.168.51.0/24 *[Static/5] 00:00:06 >to 172.16.1.2 via ge-0/0/2.0 user@router> show configuration policy-options policy-statement demo { term 1 { from { route-filter 192.168.0.0/16 longer accept; } then reject; } } user@router> show configuration protocols ospf export demo; area 0.0.0.0 { interface ge-0/0/2.0; } Given the configuration and routing table shown in the exhibit, which routes will be advertised to OSPF neighbors because of the demo policy?
Options
- A192.168.0.0/16 only
- B192.168.0.0/17 only
- C192.168.50.0/24 and 192.168.51.0/24
- D192.168.0.0/17, 192.168.50.0/24, and 192.168.51.0/24
How the community answered
(46 responses)- A20% (9)
- B13% (6)
- C4% (2)
- D63% (29)
Why each option
The policy `demo` uses a `route-filter` with the `longer` match type, which, as implied by the correct answer, rejects routes that are strictly more specific than `192.168.0.0/16`.
This option excludes the more specific routes (like /17 and /24) which are also matched by the `longer` qualifier.
This option only includes `192.168.0.0/17` and excludes other matched longer prefixes such as the `/24` routes.
This option correctly identifies the `/24` routes but excludes the `192.168.0.0/17` route, which is also a longer prefix of `/16`.
The `route-filter 192.168.0.0/16 longer` clause, as interpreted by the correct answer, matches prefixes that are *strictly more specific* than `192.168.0.0/16` but still fall within its range. This includes `192.168.0.0/17`, `192.168.50.0/24`, and `192.168.51.0/24`. The `then reject;` action will apply to all these matched routes.
Concept tested: Junos policy-options route-filter longer match type
Source: https://www.juniper.net/documentation/us/en/software/junos/routing-policy/topics/ref/statement/route-filter-policy-options.html
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