350-401 · Question #675
Refer to the exhibit. An engineer must allow R1 to advertise the 192.168.1.0/24 network to R2. R1 must perform this action without sending OSPF packets to SW1. Which command set should be applied?
The correct answer is B. R1(config)# router ospf 1. To advertise a network via OSPF while preventing OSPF packets from being sent on a specific interface, configure the network under the OSPF process and make that specific interface passive.
Question
Refer to the exhibit. An engineer must allow R1 to advertise the 192.168.1.0/24 network to R2. R1 must perform this action without sending OSPF packets to SW1. Which command set should be applied?
Exhibits
Options
- AR1(confg)# router ospf 1
- BR1(config)# router ospf 1
- CR1(config)# interface gig0/0
- DR1(config)# interface gig0/0
How the community answered
(45 responses)- A4% (2)
- B62% (28)
- C22% (10)
- D11% (5)
Why each option
To advertise a network via OSPF while preventing OSPF packets from being sent on a specific interface, configure the network under the OSPF process and make that specific interface passive.
While using `passive-interface default` and then selectively activating an interface can work, this approach is less direct than specifically making the desired interface passive when only one particular interface needs this configuration.
The `network 192.168.1.0 0.0.0.255 area 0` command includes the 192.168.1.0/24 network into the OSPF routing process, making it eligible for advertisement to R2. The `passive-interface gig0/0` command then prevents R1 from sending OSPF Hellos and updates out of interface Gig0/0 (connected to SW1), fulfilling the requirement to not send OSPF packets to SW1, while the network is still advertised to other OSPF neighbors.
The `ip ospf passive-interface` command on the interface configuration makes the interface passive, but this option lacks the necessary `network` command under the OSPF router configuration to include the 192.168.1.0/24 network into the OSPF process for advertisement to R2.
These commands configure OSPF authentication and hello intervals, which are unrelated to the requirements of advertising a specific network and preventing OSPF packets on a particular interface.
Concept tested: OSPF network advertisement and passive interface
Source: https://www.cisco.com/c/en/us/td/docs/ios/iproute_ospf/command/reference/ior_book.html#wp1026402
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