JN0-102 · Question #235
Which statement is true about routing tables on a Junos device?
The correct answer is D. They populate the forwarding table. The routing table serves as a central repository for all learned routes, and its primary function is to select the best paths to populate the forwarding table.
Question
Which statement is true about routing tables on a Junos device?
Options
- AThey purge any routes not selected as active routes.
- BThey exist in two places: the Routing Engine and the Packet Forwarding Engine.
- CThey are exclusively designed to handle dynamic routing protocols.
- DThey populate the forwarding table.
How the community answered
(39 responses)- A3% (1)
- B3% (1)
- D95% (37)
Why each option
The routing table serves as a central repository for all learned routes, and its primary function is to select the best paths to populate the forwarding table.
Routing tables store all learned routes, including inactive ones, and only the active routes are forwarded to the forwarding table; they do not purge inactive routes from the routing table itself.
Routing tables primarily reside in the Routing Engine (control plane); the forwarding table is replicated to the Packet Forwarding Engine (data plane).
Routing tables handle all types of routes, including static, direct, and aggregate routes, not exclusively dynamic routing protocols.
The routing table (Routing Information Base - RIB) collects all routes from various sources and, after applying routing policies and path selection criteria, installs the best or 'active' routes into the forwarding table (Forwarding Information Base - FIB). The forwarding table is then used by the Packet Forwarding Engine for actual packet delivery.
Concept tested: Junos routing table function
Source: https://www.juniper.net/documentation/us/en/software/junos/routing-basics/topics/topic-map/routing-tables.html
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