Network Access

Two switches are joined by an 802.1Q trunk. One switch is configured with native VLAN 1 on the trunk, the other with native VLAN 99. Spanning tree and CDP are running. What is the consequence of this configuration?

• AThe trunk forms normally and all VLANs pass, because the native VLAN only affects which VLAN carries management traffic and never the forwarding of user data.
• BThe trunk is administratively shut down by the switch as soon as the mismatch is detected through CDP, requiring a manual no shutdown to recover.
• CTraffic from the two native VLANs is merged so that frames in VLAN 1 on one side arrive in VLAN 99 on the other, creating a security and reachability problem.check_circle Correct
• DOnly VLAN 99 is permitted across the link, because the higher native VLAN number always takes precedence and prunes the lower-numbered native VLAN.

Why A is wrong: It is tempting because a native-VLAN mismatch does not bring the physical link down, but the mismatch does affect user data: untagged frames leak between the two different native VLANs.

Why B is wrong: CDP does log a native VLAN mismatch notice, but Cisco switches do not err-disable or shut the trunk for this; the port stays up and continues forwarding, which is what makes the problem subtle.

Why C is correct: Each switch sends its native-VLAN traffic untagged, and the neighbour places received untagged frames into ITS own native VLAN, so VLAN 1 and VLAN 99 traffic is bridged together across the link.

Why D is wrong: There is no rule that a higher native VLAN number wins or prunes another VLAN; native VLAN selection is purely about which VLAN is sent untagged, so this invented precedence is wrong.

Two Cisco switches are cabled together to form a Layer 2 EtherChannel using LACP. The interfaces on the first switch are set to LACP passive mode. For the bundle to negotiate and come up, which LACP mode must be configured on the matching interfaces of the second switch?

• APassive, because two passive ends still exchange LACP frames and will form the channel once both sides agree.
• BOn, because static on mode forces the link into the bundle and is fully compatible with an LACP passive neighbour.
• CActive, because at least one side must actively initiate LACP negotiation for a passive-configured neighbour to bundle the links.check_circle Correct
• DDesirable, because the desirable mode actively negotiates and pairs correctly with an LACP passive interface.

Why A is wrong: This looks safe because passive interfaces do process LACP, but passive ports only respond and never initiate, so passive-to-passive leaves both sides waiting and the channel never forms.

Why B is wrong: Mode on is tempting as a force-up option, but it disables LACP negotiation entirely, so pairing on with an LACP passive port leaves the protocols mismatched and the channel does not form.

Why C is correct: LACP passive ports respond but do not start negotiation, so the far end must be active to send the first LACPDUs; active-passive is a valid combination that brings the channel up.

Why D is wrong: Desirable does actively negotiate, but it is a PAgP keyword, not an LACP mode, so it cannot interoperate with an LACP passive port and the bundle stays down.

An access port configured with PortFast and connected to a single workstation suddenly receives a BPDU because a switch was cabled into that wall socket. With BPDU Guard absent, how does Rapid PVST+ treat the port?

• AThe port stays an edge port and ignores the BPDU, since PortFast permanently disables spanning tree on that interface
• BThe port is placed in err-disabled immediately, exactly as BPDU Guard would force, and must be manually re-enabled
• CThe port forwards the BPDU upstream toward the root but otherwise remains a fast-transitioning edge port
• DThe port loses edge status, stops skipping the transition states, and rejoins the normal spanning-tree process for that VLANcheck_circle Correct

Why A is wrong: PortFast does not disable STP; it only assumes an edge port, and that assumption is dropped the moment a BPDU arrives, so the port cannot simply ignore it.

Why B is wrong: Err-disable on BPDU receipt is the behaviour of BPDU Guard; the stem states BPDU Guard is absent, so the port reverts to normal STP rather than shutting down.

Why C is wrong: An edge port that receives a BPDU does not stay an edge port; it loses that designation, so continuing to behave as a fast-transitioning edge port is incorrect.

Why D is correct: Receiving a BPDU proves another switch is attached, so the port abandons its edge role and runs the standard RSTP transition through discarding and learning as needed.

A branch AP is configured so that, if its CAPWAP tunnel to the central WLC across the WAN fails, already-associated clients on a locally switched WLAN keep passing traffic to local resources. Which AP mode provides this behaviour?

• ALocal mode, because the AP tunnels all client data back to the WLC and therefore survives any WAN outage
• BMonitor mode, because the AP scans the air full time and forwards client data only when the tunnel recovers
• CFlexConnect mode, because it can switch client traffic locally and enter standalone operation when the CAPWAP link is lostcheck_circle Correct
• DSniffer mode, because it captures and locally switches branch client frames during a WAN failure

Why A is wrong: Local mode is tempting as the default deployment mode, but it tunnels all client data to the WLC over CAPWAP, so a lost tunnel drops the WLAN rather than keeping traffic flowing locally.

Why B is wrong: Monitor mode is plausible to a candidate who recalls it handles RF tasks, but it serves no clients at all - it is a dedicated sensor for IDS, location, and rogue detection.

Why C is correct: FlexConnect lets the AP switch client data locally at the branch and continue serving already-authenticated clients in standalone mode when the WLC is unreachable, which is exactly the described behaviour.

Why D is wrong: Sniffer mode sounds like local capture, but the AP only captures and forwards 802.11 frames to a remote analyser and carries no production client traffic, so it cannot keep a WLAN running.

A network technician needs a discovery protocol that will exchange neighbour information with switches, routers, and IP phones from several different vendors across the same campus. Which statement correctly describes the protocol that fits this requirement?

• ACDP is the only suitable choice because it is defined by the IEEE and is therefore understood by every vendor's equipment.
• BLLDP is suitable because it is the vendor-neutral IEEE 802.1AB standard and is supported across multi-vendor devices.check_circle Correct
• CCDP is suitable because it is an open standard maintained by the IETF for cross-vendor neighbour discovery.
• DLLDP is unsuitable because it runs only on Cisco hardware and must be paired with CDP to reach other vendors.

Why A is wrong: This is tempting because CDP is widely deployed, but CDP is a Cisco-proprietary protocol, not an IEEE standard, so it is not generally supported by other vendors.

Why B is correct: LLDP is defined by IEEE 802.1AB as an open, vendor-neutral link-layer discovery protocol, so it can exchange neighbour information between equipment from different vendors.

Why C is wrong: This mixes up the standards bodies: CDP is proprietary to Cisco and is not maintained by the IETF, so it cannot be relied on across multiple vendors.

Why D is wrong: This inverts the facts: LLDP is the vendor-neutral protocol, while CDP is the Cisco-proprietary one, so LLDP is exactly what works across vendors.