ACSP Routing Protocols & IP Addressing 3 — Questions and Answers
Question 1: An ArubaOS-CX switch has two equal-cost paths to a destination in its routing table. What behavior does the switch exhibit by default?
- It installs only the first learned route
- It uses ECMP to load-balance across both paths (Correct answer)
- It uses spanning tree to block one path
- It selects the path with the lowest next-hop IP
Correct answer: It uses ECMP to load-balance across both paths
ArubaOS-CX supports Equal-Cost Multi-Path (ECMP) routing, distributing traffic across multiple equal-cost paths by default.
Question 2: Which BGP attribute is used first when selecting the best path among multiple routes to the same prefix?
- MED
- Local Preference
- Weight (Correct answer)
- AS Path length
Correct answer: Weight
Cisco and Aruba implementations evaluate Weight first in BGP best-path selection; it is locally significant and not advertised to peers.
Question 3: A host is assigned the IP address 192.168.10.50/27. What is the broadcast address of this subnet?
- 192.168.10.63 (Correct answer)
- 192.168.10.62
- 192.168.10.255
- 192.168.10.127
Correct answer: 192.168.10.63
A /27 subnet has 32 addresses; the block starting at 192.168.10.32 ends with broadcast 192.168.10.63.
Question 4: On an ArubaOS-CX switch, what is the purpose of the 'ip helper-address' command on a VLAN interface?
- It sets the default gateway for the VLAN
- It forwards DHCP broadcast requests to a unicast DHCP server (Correct answer)
- It enables DHCP snooping on the VLAN
- It configures a secondary IP address for the interface
Correct answer: It forwards DHCP broadcast requests to a unicast DHCP server
The 'ip helper-address' command configures DHCP relay, converting client broadcast requests to unicast packets forwarded to the specified server.
Question 5: Which routing protocol uses the Diffusing Update Algorithm (DUAL) to guarantee loop-free paths?
- OSPF
- BGP
- RIP
- EIGRP (Correct answer)
Correct answer: EIGRP
EIGRP uses the DUAL algorithm to compute loop-free paths and identify feasible successors for fast convergence.
Question 6: An ArubaOS-CX switch needs to redistribute connected routes into OSPF. Which configuration element is required?
- A route map is always mandatory
- The 'redistribute connected' command under the OSPF process (Correct answer)
- Connected routes are redistributed automatically
- OSPF must be disabled and re-enabled after adding connected networks
Correct answer: The 'redistribute connected' command under the OSPF process
The 'redistribute connected' command under the OSPF router configuration redistributes directly connected routes into OSPF as external routes.
Question 7: What is the function of a BGP route reflector in an iBGP topology?
- It translates eBGP routes to iBGP format
- It allows iBGP routes to be re-advertised to other iBGP peers without full mesh (Correct answer)
- It filters BGP routes based on community strings
- It performs NAT for BGP peering sessions
Correct answer: It allows iBGP routes to be re-advertised to other iBGP peers without full mesh
A BGP route reflector eliminates the full-mesh iBGP requirement by re-advertising received iBGP routes to its clients.
ACSP Routing Protocols & IP Addressing 3
An ArubaOS-CX switch has two equal-cost paths to a destination in its routing table.
What behavior does the switch exhibit by default?