According to theFortiSwitchOS 7.6 Administration Guideand theFortiSwitch 7.6 Study Guide, the Routing Information Base (RIB) contains all potential routes discovered by the switch, but theForwarding Information Base (FIB)only includes the "best" active routes used for hardware packet forwarding. When the routing process receives multiple paths to the exact same destination (in this case, the default route 0.0.0.0
/0), it must select the most reliable source based on a specific hierarchy.
The primary tie-breaker for routes from different protocols is theAdministrative Distance (AD). AD is a value from 1 to 255 that represents the trustworthiness of the routing source, where alower value is more preferred. In the provided exhibit:
* TheOSPFroute has an AD of110(shown as [110/10]).
* TheStaticroute has been configured with an AD of220(shown as [220/0]).
Because the OSPF route's AD (110) is lower than the Static route's AD (220), the system considers the OSPF route to be superior. Consequently, only the OSPF route is "Selected" and installed into theFIB. The static route remains in the RIB as a "backup" or floating static route; it will only be moved to the FIB if the preferred OSPF route becomes unavailable. Option D is incorrect because having identical prefixes is not a
"conflict" but a standard part of route selection where AD decides the winner. Option A is incorrect because metric is only compared if the AD is identical.