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Aruba ACSA practice questions

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Question 1Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

On an ArubaOS-CX switch, which command displays the running configuration of the current context?

  1. display current-config
  2. show config active
  3. get running-config
  4. show running-config Correct answer.

Explanation

ArubaOS-CX uses a show running-config command to output the active configuration, optionally scoped to the current context such as an interface. The command set follows a CLI convention distinct from Comware's display commands.

Question 2Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which ArubaOS-CX command saves the running configuration so it persists across a reboot?

  1. checkpoint auto
  2. copy running-config startup-config Correct answer.
  3. write memory
  4. save configuration

Explanation

ArubaOS-CX persists configuration by copying the running configuration to the startup configuration with copy running-config startup-config. The older write memory syntax is associated with other platforms.

Question 3Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network engineer wants a single ArubaOS-CX interface to pass frames for VLAN 10 and VLAN 20 to a downstream switch. Which configuration achieves this?

  1. Configure the port with an IP address in each VLAN subnet.
  2. Configure the port as a trunk and allow VLANs 10 and 20 with vlan trunk allowed 10,20. Correct answer.
  3. Assign the port as an access port in VLAN 10 and add VLAN 20 as a secondary VLAN.
  4. Create a LAG and assign both VLANs to the LAG as access VLANs.

Explanation

A trunk port carries traffic for multiple VLANs, and on ArubaOS-CX the permitted VLANs are set with vlan trunk allowed. Access ports carry a single untagged VLAN, so they cannot serve two VLANs simultaneously.

Question 4Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What is the default administrative state of an interface on an ArubaOS-CX switch after it is created?

  1. Auto-negotiating only
  2. Administratively up
  3. Administratively down Correct answer.
  4. Passive

Explanation

Newly created interfaces on ArubaOS-CX are administratively down until enabled with the no shutdown command. This prevents unintended traffic on ports that have not been deliberately activated.

Question 5Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which statement describes the behavior of the ArubaOS-CX default VLAN 1?

  1. It is reserved for voice traffic only.
  2. It is deleted automatically when a new VLAN is created.
  3. It is the management VLAN and cannot carry user traffic.
  4. It exists by default and all access ports are members until reassigned. Correct answer.

Explanation

VLAN 1 is the default VLAN present on the switch, and interfaces are members of it until they are explicitly assigned to another VLAN. It can carry user traffic like any other VLAN.

Question 6Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

An engineer needs to verify which VLANs are currently allowed on trunk interface 1/1/1 on an ArubaOS-CX switch. Which command is most appropriate?

  1. show vlan trunk 1/1/1
  2. show interface 1/1/1 trunk
  3. show interface 1/1/1 switchport Correct answer.
  4. show running-config interface 1/1/1

Explanation

The show interface switchport command reports switchport details including the operational mode and the VLANs allowed or carried on the port. This gives a consolidated view rather than requiring the full configuration block.

Question 7Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which spanning tree protocol is the default on ArubaOS-CX switches?

  1. PVST+
  2. MSTP (802.1s)
  3. RSTP (802.1w) Correct answer.
  4. STP (802.1D)

Explanation

ArubaOS-CX enables Rapid Spanning Tree Protocol by default, providing faster convergence than legacy 802.1D STP. MSTP and other modes can be selected when needed.

Question 8Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

In an RSTP topology, which port role provides an alternate path to the root bridge and stays in a discarding state while the primary path is healthy?

  1. Root port
  2. Designated port
  3. Alternate port Correct answer.
  4. Edge port

Explanation

An alternate port offers a backup path toward the root bridge and remains discarding unless the root port fails. This allows rapid failover without recalculating the whole topology.

Question 9Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A port configured as an RSTP edge port is connected to a workstation. What is the expected spanning tree behavior?

  1. It participates in topology change notifications and blocks briefly on link up.
  2. It transitions directly to forwarding and does not generate topology changes on link up or down. Correct answer.
  3. It is excluded from the spanning tree instance entirely.
  4. It always becomes a designated port and floods BPDUs to the workstation.

Explanation

Edge ports connect to end stations and bypass the listening and learning states, moving straight to forwarding. Because they do not create loops, their link transitions do not trigger topology change notifications.

Question 10Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which feature allows multiple physical links between two ArubaOS-CX switches to be bundled into one logical link for increased bandwidth and redundancy?

  1. MSTP instance grouping
  2. Loop protection
  3. Link aggregation group Correct answer.
  4. VLAN trunking

Explanation

A link aggregation group (LAG) combines multiple physical links into a single logical interface, aggregating bandwidth and providing redundancy if one member fails. Spanning tree treats the LAG as one link.

Question 11Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

When configuring a static LAG on ArubaOS-CX, which command creates the logical aggregation interface?

  1. interface bundle 10
  2. interface port-channel 10
  3. interface lag 10 Correct answer.
  4. interface trunk 10

Explanation

ArubaOS-CX creates a static LAG with interface lag followed by the LAG number, then physical members are added with the lag command under each member interface. The lag keyword distinguishes it from physical interface naming.

Question 12Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which protocol provides dynamic link aggregation negotiation between ArubaOS-CX and a peer switch?

  1. VLAN trunking protocol
  2. LLDP
  3. LACP (802.3ad) Correct answer.
  4. STP

Explanation

LACP, defined in 802.3ad, negotiates link aggregation dynamically so both ends agree on which links form the bundle. LLDP is a neighbor discovery protocol and does not manage aggregation.

Question 13Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A switch port configured with the command spanning-tree bpdu-guard is connected to a device that begins sending BPDUs. What happens to the port?

  1. It transitions to a blocking state or is disabled based on configuration. Correct answer.
  2. It forwards the BPDUs to the CPU but stays up.
  3. It converts to an edge port automatically.
  4. It resets the spanning tree priority to default.

Explanation

BPDU guard protects edge ports by reacting when BPDUs are received, placing the port in an err-disabled or blocking state depending on configuration. This prevents unauthorized switches from affecting the topology.

Question 14Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What is the purpose of the ArubaOS-CX command loop-protect on an access port?

  1. It assigns the port to a voice VLAN.
  2. It detects and mitigates Layer 2 loops on ports where spanning tree is not expected. Correct answer.
  3. It disables spanning tree on the port.
  4. It aggregates the port into a LAG.

Explanation

Loop protection detects looping conditions on ports that may not participate in spanning tree, such as edge ports, and takes action to break the loop. It supplements rather than replaces spanning tree.

Question 15Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command on ArubaOS-CX displays the MAC address table with VLAN and port associations?

  1. show ip route
  2. show lldp neighbors
  3. show mac-address-table Correct answer.
  4. show arp

Explanation

The MAC address table is displayed with show mac-address-table, showing learned MAC addresses, their VLANs, and the associated ports. This is used to verify Layer 2 forwarding entries.

Question 16Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A switch learns a MAC address on port 1/1/5. Later, a frame destined for that MAC arrives on port 1/1/9. What does the switch do with the learned entry?

  1. It creates a second entry for the same MAC on 1/1/9.
  2. It drops the frame and logs an error.
  3. It keeps the entry on 1/1/5 and floods the frame.
  4. It updates the entry to point to 1/1/9. Correct answer.

Explanation

A switch maintains one entry per MAC address per VLAN and updates the port association when the address is seen on a new port. This reflects the station having moved.

Question 17Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which ArubaOS-CX feature allows a switch to authenticate users via 802.1X and dynamically assign them to a VLAN?

  1. Port security
  2. RADIUS-based dynamic VLAN assignment with 802.1X Correct answer.
  3. LLDP-MED
  4. DHCP snooping

Explanation

802.1X with a RADIUS server can return authorization attributes, including a VLAN, that the switch applies to the authenticated port. This provides identity-based VLAN assignment.

Question 18Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What does DHCP snooping do on an ArubaOS-CX switch?

  1. It assigns IP addresses to clients from a local pool.
  2. It filters DHCP server messages on untrusted ports to prevent rogue servers. Correct answer.
  3. It encrypts DHCP traffic between switches.
  4. It converts DHCP to static addressing.

Explanation

DHCP snooping designates trusted ports where legitimate DHCP servers reside and blocks server messages arriving on untrusted ports. It also builds a binding table used by features such as dynamic ARP protection.

Question 19Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command enables an interface on ArubaOS-CX after it has been administratively disabled?

  1. set state up
  2. enable
  3. interface up
  4. no shutdown Correct answer.

Explanation

Interfaces are enabled with no shutdown and disabled with shutdown in the interface context. This toggles the administrative state of the port.

Question 20Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

An engineer configures an ArubaOS-CX switch with two VLANs and wants inter-VLAN routing between them. Which approach enables this on the switch itself?

  1. Add both VLANs to a single access port.
  2. Create a trunk between two access ports.
  3. Enable DHCP snooping on both VLANs.
  4. Assign each VLAN an SVI with an IP address and enable IP routing. Correct answer.

Explanation

Inter-VLAN routing on the switch requires switched virtual interfaces with IP addresses for each VLAN and IP routing enabled globally. The switch then routes between the connected subnets.

Question 21Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which statement about ArubaOS-Switch (ProVision/ArubaOS-Switch) trunk configuration is accurate?

  1. A trunk port must use LACP.
  2. A trunk port is always an access port.
  3. A trunk port carries multiple VLANs, and VLANs are added with the tagged keyword. Correct answer.
  4. A trunk port can carry only VLAN 1.

Explanation

On ArubaOS-Switch, a trunk is a port carrying multiple VLANs, and VLAN membership is configured with the tagged keyword in the VLAN context. Untagged membership corresponds to access behavior.

Question 22Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which spanning tree mode on ArubaOS-Switch provides per-VLAN spanning tree instances similar to PVST?

  1. Rapid PVST
  2. MSTP
  3. PVST+ Correct answer.
  4. STP

Explanation

ArubaOS-Switch supports a PVST+ mode that runs a separate spanning tree instance per VLAN, interoperating with per-VLAN implementations. MSTP maps VLANs to instances but uses a different model.

Question 23Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What is the effect of the ArubaOS-CX command spanning-tree priority 0 on a switch?

  1. It makes the switch the most likely to become root bridge. Correct answer.
  2. It makes the switch the least likely to become root.
  3. It disables spanning tree.
  4. It sets the port cost to zero.

Explanation

Bridge priority is compared to elect the root bridge, and the lowest value wins. Setting priority to 0 makes the switch the preferred root for that instance.

Question 24Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network uses MSTP with multiple regions. Which three parameters must match for switches to belong to the same MST region?

  1. Region name, revision level, and VLAN-to-instance mapping Correct answer.
  2. Hostname, management IP, and LACP key
  3. Bridge priority, port cost, and hello time
  4. VLAN ID, MAC address, and IP address

Explanation

MST regions are defined by matching region name, revision number, and the VLAN-to-instance mapping. Switches with any mismatch are treated as separate regions.

Question 25Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command on ArubaOS-CX shows LLDP neighbor information for a specific interface?

  1. show lldp info remote-device
  2. show cdp neighbors
  3. show interface lldp
  4. show lldp neighbors Correct answer.

Explanation

LLDP neighbor details are displayed with show lldp neighbors, which lists discovered neighbors and their connecting ports. This helps verify physical topology and cabling.

Question 26Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

On an ArubaOS-CX switch, which VLAN is assigned to all access ports by default?

  1. VLAN 10
  2. No VLAN is assigned by default
  3. VLAN 1 Correct answer.
  4. VLAN 100

Explanation

By default, all access ports on ArubaOS-CX switches are members of VLAN 1, which is the default VLAN. This VLAN carries untagged traffic until changed.

Question 27Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command is used on ArubaOS-CX to create a VLAN and enter its configuration context?

  1. set vlan 10
  2. vlan 10 Correct answer.
  3. create vlan 10
  4. vlan database

Explanation

The command 'vlan 10' from the global configuration mode creates VLAN 10 (if it does not exist) and enters the VLAN configuration context.

Question 28Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which statement about the default gateway configuration on an ArubaOS-CX switch is correct?

  1. The default gateway is configured globally with the ip default-gateway command. Correct answer.
  2. The default gateway is configured on each access port.
  3. The default gateway is configured per VLAN interface with the ip route command.
  4. The default gateway is automatically learned via DHCP.

Explanation

On ArubaOS-CX, the default gateway for management traffic is set globally using 'ip default-gateway <address>'. It is not configured per interface or learned automatically.

Question 29Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What is the purpose of the ArubaOS-CX command 'ip route 0.0.0.0/0 192.168.1.1'?

  1. It creates a default route via 192.168.1.1. Correct answer.
  2. It assigns an IP address to an interface.
  3. It configures a static ARP entry.
  4. It enables DHCP on the switch.

Explanation

The command 'ip route 0.0.0.0/0 192.168.1.1' adds a static default route with next-hop 192.168.1.1, used when no more specific route exists.

Question 30Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network engineer wants to allow only VLANs 10 and 20 on a trunk port on an ArubaOS-CX switch. Which command should be used?

  1. switchport mode trunk vlan 10,20
  2. switchport trunk allowed vlan 10,20 Correct answer.
  3. switchport trunk allowed vlan add 10,20
  4. switchport trunk native vlan 10,20

Explanation

The command 'switchport trunk allowed vlan 10,20' sets the allowed VLAN list to exactly VLANs 10 and 20, removing any others. This restricts the trunk to only those VLANs.

Question 31Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which ArubaOS-CX command displays the running configuration of a specific interface?

  1. show interface 1/1/1 configuration
  2. show running-config interface 1/1/1 Correct answer.
  3. show interface 1/1/1 running-config
  4. show config interface 1/1/1

Explanation

The command 'show running-config interface 1/1/1' displays the current configuration of the specified interface from the running configuration.

Question 32Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network administrator needs to configure an access port for VLAN 50 on an ArubaOS-CX switch. Which command sequence is correct?

  1. interface 1/1/1 no shutdown switchport access vlan 50
  2. interface 1/1/1 vlan 50 switchport access
  3. interface 1/1/1 switchport mode access switchport access vlan 50 Correct answer.
  4. interface 1/1/1 switchport access vlan 50 no shutdown

Explanation

To configure an access port for VLAN 50, you set the port to access mode with 'switchport mode access' and then assign the VLAN with 'switchport access vlan 50'. The 'no shutdown' command may be needed if the port is disabled, but it is not part of the VLAN assignment.

Question 33Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which protocol is used by ArubaOS-CX switches to prevent loops when multiple switches are connected in a redundant topology?

  1. LACP
  2. LLDP
  3. OSPF
  4. RSTP Correct answer.

Explanation

Rapid Spanning Tree Protocol (RSTP) is used to prevent Layer 2 loops by blocking redundant paths. LLDP is for neighbor discovery, LACP for link aggregation, and OSPF for routing.

Question 34Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command on ArubaOS-CX is used to enable LLDP globally?

  1. lldp enable
  2. lldp global
  3. lldp run Correct answer.
  4. enable lldp

Explanation

The command 'lldp run' enables LLDP globally on ArubaOS-CX switches. It is executed in global configuration mode.

Question 35Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

What is the effect of the ArubaOS-CX command 'spanning-tree port-type admin-edge' on an interface?

  1. It configures the port as a point-to-point link.
  2. It forces the port to be an edge port and immediately transitions to forwarding. Correct answer.
  3. It sets the port priority for root bridge election.
  4. It disables spanning tree on the port.

Explanation

The 'admin-edge' port type configures the port as an edge port, which assumes no switches are connected. Such ports transition directly to forwarding without waiting for spanning tree convergence.

Question 36Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network engineer wants to configure a static LAG on ArubaOS-CX. Which command is used to create the LAG interface?

  1. interface trunk 1
  2. lag 1
  3. interface port-channel 1
  4. interface lag 1 Correct answer.

Explanation

On ArubaOS-CX, a static LAG is created with 'interface lag <number>', which enters the LAG interface configuration context.

Question 37Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which command on ArubaOS-CX displays the status of all VLANs, including their operational state and member ports?

  1. show vlan status
  2. show vlan Correct answer.
  3. show vlan brief
  4. show vlan summary

Explanation

The command 'show vlan' displays a list of all VLANs with their status and the ports assigned to each. It is the primary command for VLAN status.

Question 38Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

In an ArubaOS-CX switch, what is the purpose of the 'ip source-binding' command?

  1. It binds a VLAN to a physical port.
  2. It binds an IP address to a MAC address and VLAN to prevent IP spoofing. Correct answer.
  3. It binds a DHCP server to a VLAN.
  4. It binds a static route to an interface.

Explanation

The 'ip source-binding' command creates a static binding of IP, MAC, and VLAN, which is used by features like IP Source Guard to filter spoofed traffic.

Question 39Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

Which statement about the ArubaOS-CX command 'spanning-tree mode mstp' is true?

  1. It configures the switch to use Multiple Spanning Tree Protocol, allowing multiple VLANs to be mapped to a single instance. Correct answer.
  2. It configures the switch to use PVST+ for per-VLAN load balancing.
  3. It disables spanning tree and enables TRILL.
  4. It enables Rapid Spanning Tree Protocol with a single instance for all VLANs.

Explanation

MSTP (Multiple Spanning Tree Protocol) allows grouping VLANs into multiple spanning tree instances, providing better load balancing and scalability than a single instance.

Question 40Switching fundamentals (ArubaOS-CX/ArubaOS-Switch)

A network uses MSTP. Which three parameters must match for switches to be in the same MST region?

  1. Region name, revision number, and VLAN-to-instance mapping. Correct answer.
  2. Revision number, max age, and forward delay.
  3. Region name, bridge priority, and hello time.
  4. VLAN-to-instance mapping, bridge priority, and port cost.

Explanation

For switches to belong to the same MST region, they must have identical region name, revision number, and VLAN-to-instance mapping. Other parameters like timers and priorities can differ.

Question 41VLANs and Layer 2 technologies

Which IEEE standard defines VLAN tagging for Ethernet frames?

  1. 802.3ad
  2. 802.1Q Correct answer.
  3. 802.1X
  4. 802.1D

Explanation

IEEE 802.1Q specifies the VLAN tag inserted into Ethernet frames, including the 12-bit VLAN identifier field. It is the basis for 802.1Q trunking between switches.

Question 42VLANs and Layer 2 technologies

How many bits does the VLAN identifier field in an 802.1Q tag contain?

  1. 10
  2. 8
  3. 12 Correct answer.
  4. 16

Explanation

The 802.1Q tag carries a 12-bit VLAN ID, which allows values 0 through 4095. Usable VLAN IDs range from 1 to 4094.

Question 43VLANs and Layer 2 technologies

What is the purpose of the native VLAN on an 802.1Q trunk?

  1. It encrypts traffic between switches
  2. It carries untagged traffic on the trunk Correct answer.
  3. It is the only VLAN allowed to use STP
  4. It is reserved for switch management only

Explanation

On an 802.1Q trunk, frames belonging to the native VLAN are sent without a tag. Both ends of the trunk must agree on the native VLAN to avoid misforwarding.

Question 44VLANs and Layer 2 technologies

A switch port configured as an access port in VLAN 20 receives an untagged frame from a PC. What does the switch do with the frame?

  1. Tags it with VLAN 20 and forwards it within VLAN 20 Correct answer.
  2. Drops it because it is untagged
  3. Sends it out all trunk ports untagged
  4. Tags it with the native VLAN and forwards it

Explanation

An access port assigns its configured VLAN to untagged frames received from attached devices. The frame is then switched only within that VLAN.

Question 45VLANs and Layer 2 technologies

Which statement describes a VLAN trunk port?

  1. It assigns all frames to a single VLAN
  2. It connects only to end-user devices
  3. It blocks all tagged frames by default
  4. It carries traffic for multiple VLANs using tagging Correct answer.

Explanation

A trunk port carries frames for multiple VLANs between network devices, using 802.1Q tags to identify VLAN membership. Untagged traffic uses the native VLAN.

Question 46VLANs and Layer 2 technologies

What is the primary function of the Spanning Tree Protocol in a Layer 2 network?

  1. To load-balance traffic across all links
  2. To prevent Layer 2 loops by blocking redundant paths Correct answer.
  3. To assign VLANs to access ports
  4. To authenticate devices on switch ports

Explanation

STP builds a loop-free logical topology by placing redundant ports into a blocking state. This prevents broadcast storms and MAC table instability caused by Layer 2 loops.

Question 47VLANs and Layer 2 technologies

Which protocol is used to negotiate a trunk link and exchange VLAN information between switches?

  1. DTP Correct answer.
  2. VTP
  3. LLDP
  4. LACP

Explanation

Dynamic Trunking Protocol (DTP) negotiates whether a link becomes a trunk and the encapsulation type. It operates between directly connected Cisco-style switches.

Question 48VLANs and Layer 2 technologies

What does the PortFast feature do on a switch access port?

  1. It enables per-VLAN load balancing
  2. It immediately places the port in the forwarding state Correct answer.
  3. It enables trunk negotiation
  4. It blocks BPDUs on the port

Explanation

PortFast causes an access port to transition directly to forwarding, skipping the listening and learning states. It should only be used on ports connected to end devices.

Question 49VLANs and Layer 2 technologies

A switch port is configured with BPDU Guard. What happens when the port receives a BPDU?

  1. The BPDU is forwarded to all VLANs
  2. The port is placed into an error-disabled state Correct answer.
  3. The BPDU is dropped and the port stays up
  4. The port becomes a trunk port

Explanation

BPDU Guard err-disables a port that receives a BPDU, protecting the topology from unexpected switch connections on edge ports. It is typically paired with PortFast on access ports.

Question 50VLANs and Layer 2 technologies

Which STP port role is elected on a non-root switch to provide the best path toward the root bridge?

  1. Designated port
  2. Blocked port
  3. Alternate port
  4. Root port Correct answer.

Explanation

Each non-root switch elects one root port, which is the port with the lowest cost path to the root bridge. Designated ports face downstream segments.