350-401 · Question #744
Which two options describe the effect of configuring an interface as passive under OSPF? (Choose two)
The correct answer is B. The interface processes OSPF hello packets but does not send hello packets. C. An adjacency cannot be established, and the interface is included in the routing protocol update.. When an interface is configured as passive under OSPF, it stops sending OSPF hello packets, preventing the formation of adjacencies with other OSPF routers. However, the network connected to this passive interface will still be advertised by OSPF into the routing domain.
Question
Options
- AAn adjacency cannot be established, and the interface is not included in the routing protocol
- BThe interface processes OSPF hello packets but does not send hello packets.
- CAn adjacency cannot be established, and the interface is included in the routing protocol update.
- DThe interface processes OSPF hello packets and also sends hello packets.
- EAn adjacency can be established, and the interface is not included in the routing protocol update.
How the community answered
(48 responses)- B90% (43)
- D4% (2)
- E6% (3)
Why each option
When an interface is configured as passive under OSPF, it stops sending OSPF hello packets, preventing the formation of adjacencies with other OSPF routers. However, the network connected to this passive interface will still be advertised by OSPF into the routing domain.
While an adjacency cannot be established, the network connected to a passive interface *is* included in the routing protocol updates, making the second part of the statement incorrect.
A passive OSPF interface stops sending OSPF hello packets, which prevents it from forming adjacencies with neighboring routers, as hello packets are essential for neighbor discovery and relationship establishment.
An adjacency cannot be established on a passive OSPF interface because it does not send hello packets, but the network directly connected to this passive interface is still advertised by OSPF into the routing domain.
A passive OSPF interface explicitly *does not send* hello packets; this statement directly contradicts the function of a passive interface.
An adjacency *cannot* be established on a passive OSPF interface because it does not send the necessary hello packets for neighbor discovery and adjacency formation.
Concept tested: OSPF passive interface behavior
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-3s/iro-xe-3s-book/ospf-passive-int.html
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