Change Default Route Preference in [edit protocols] Hierarchy | Juniper Exam JN0-102

BD

In Junos OS, the default route preference determines the priority of different routing protocols to use when selecting a default route. When there are multiple default routes available, the routing table selects the one with the highest preference value. The default preference values are set by Juniper and are the same for all Junos routing protocols. However, you can modify these values under the [edit protocols] hierarchy to suit your network requirements.

The two routing information sources that you can change the default preference value for are OSPF and BGP.

OSPF (Open Shortest Path First) is an interior gateway protocol that is used to distribute routing information within a single autonomous system (AS). The default preference value for OSPF is 10, which means that it has a higher priority than other routing protocols such as RIP or static routing. You can modify this preference value by configuring the [edit protocols ospf] hierarchy in the Junos CLI.

BGP (Border Gateway Protocol) is an exterior gateway protocol that is used to exchange routing information between different autonomous systems (ASes). The default preference value for BGP is 170, which is lower than OSPF but higher than other routing protocols. You can modify this preference value by configuring the [edit protocols bgp] hierarchy in the Junos CLI.

Local and direct are not routing protocols, but rather methods of obtaining routing information. Local routes are those that are configured manually on a router, such as a static route. Direct routes are those that are learned automatically from a directly connected network, such as an Ethernet interface. The default preference value for both local and direct routes is 0, which is the highest priority value in the routing table. Therefore, you cannot change the default preference value for these sources under the [edit protocols] hierarchy.