ACSP OSPF Routing Configuration 2 — Questions and Answers
Question 1: In an Aruba switch running OSPF, what is the effect of configuring a router-id manually before any OSPF adjacencies form?
- The router uses the configured ID permanently even if loopback IPs change (Correct answer)
- The router ignores the manual ID and picks the highest loopback
- The router resets all existing adjacencies immediately upon configuration
- The router-id is only used for ABR elections
Correct answer: The router uses the configured ID permanently even if loopback IPs change
A manually configured router-id takes precedence over loopback or physical interface IPs and persists unless changed and OSPF is reset.
Question 2: Which OSPF network type is automatically assigned to an Aruba switch interface configured as a point-to-point VLAN link?
- Broadcast (Correct answer)
- Point-to-point
- Non-broadcast
- Point-to-multipoint
Correct answer: Broadcast
Ethernet/VLAN interfaces default to broadcast network type in OSPF unless explicitly changed with the ip ospf network command.
Question 3: An Aruba switch is configured with 'ip ospf passive-interface vlan 10'. What behavior change occurs on VLAN 10?
- OSPF hellos are suppressed, preventing neighbor formation but still advertising the network (Correct answer)
- OSPF completely ignores the VLAN 10 network
- The interface sends hellos but does not process received hellos
- Passive interfaces only affect external route redistribution
Correct answer: OSPF hellos are suppressed, preventing neighbor formation but still advertising the network
A passive interface suppresses OSPF hello packets, preventing adjacencies while still advertising the subnet as an OSPF route.
Question 4: What happens to OSPF routes when the OSPF process is restarted on an Aruba switch without graceful restart configured?
- All OSPF routes are immediately removed from the routing table during convergence (Correct answer)
- Routes remain until the process finishes restarting
- Only external OSPF routes are removed
- Routes are moved to a backup routing table
Correct answer: All OSPF routes are immediately removed from the routing table during convergence
Without graceful restart, restarting the OSPF process drops all OSPF-learned routes from the RIB until adjacencies re-form and SPF recalculates.
Question 5: In OSPF area design on Aruba switches, what is the primary purpose of a stub area?
- To reduce LSA flooding by blocking Type 5 external LSAs from entering the area (Correct answer)
- To allow only Type 1 LSAs within the area
- To prevent inter-area routes from being advertised
- To eliminate the need for a DR/BDR election
Correct answer: To reduce LSA flooding by blocking Type 5 external LSAs from entering the area
Stub areas block Type 5 AS-external LSAs, reducing the LSDB size by replacing external routes with a default route from the ABR.
Question 6: When configuring OSPF on an Aruba switch, which command correctly places VLAN 20 (10.1.20.0/24) into OSPF area 0?
- network 10.1.20.0/24 area 0
- ip ospf area 0 on the VLAN interface
- Both 'network' command under router ospf and interface-level 'ip ospf area' are valid (Correct answer)
- area 0 network 10.1.20.0 255.255.255.0
Correct answer: Both 'network' command under router ospf and interface-level 'ip ospf area' are valid
Aruba AOS-CX supports both the traditional 'network' statement under router ospf and the per-interface 'ip ospf area' command for placing interfaces into OSPF areas.
Question 7: What is the OSPF cost assigned to a 10 Gbps interface on an Aruba switch using the default reference bandwidth of 100 Mbps?
- 1 (Correct answer)
- 10
- 100
- 1000
Correct answer: 1
OSPF cost = reference bandwidth / interface bandwidth; 100 Mbps / 10,000 Mbps = 0.01, which rounds up to the minimum cost of 1.
ACSP OSPF Routing Configuration 2
In an Aruba switch running OSPF, what is the effect of configuring a router-id manually before any OSPF adjacencies form?