CCNA Switching Network Access Questions

The port is not in an err-disabled state; BPDU Guard causes the port to be shut down, not to stay in listening.

Misunderstanding that PortFast bypasses timers completely on access ports; the high forward delay is irrelevant if PortFast were active.

The assumption that the server is sending BPDUs is contradicted by the output showing zero BPDUs received.

Root Guard uses a specific 'root-inconsistent' state, not the generic 'blocking' state.

BPDU Guard triggers err-disable, not blocking. Blocking is an STP state, not an error state.

Root Guard and BPDU Guard have different effects: root-inconsistent vs. err-disable. Mixing them up is a common error.

Voice VLANs operate on access ports by tagging voice traffic while keeping PC traffic untagged in the data VLAN. A trunk is not required.

Native VLAN mismatches on trunks would affect both data and voice VLANs if both were allowed. The PC works, ruling out a general trunk issue.

The phone would work if it was sending voice traffic on the data VLAN (10), because VLAN 10 exists. The phone failing indicates a missing voice VLAN, not a misconfiguration on the phone.

Reducing all AP transmit power to zero would completely disable the wireless network, making it impossible for users to connect or experience any performance, which does not address the issue of slow performance in a dense office environment.

Changing every AP to the same channel would lead to co-channel interference, exacerbating the slow wireless performance issue rather than resolving it. In a dense office environment, this configuration would reduce overall throughput and increase contention among devices.

Disabling WPA2 security would not address the issue of slow wireless performance in a dense office environment; instead, it would compromise network security and potentially allow unauthorized access, worsening the situation.

Root Guard and UDLD do not directly address the requirement for a port to quickly transition to forwarding while shutting down upon receiving a BPDU. Root Guard is used to prevent a port from becoming a root port, while UDLD is for detecting unidirectional links.

Loop Guard and native VLAN do not directly address the requirement for a port to quickly transition to forwarding while shutting down upon receiving a BPDU. Loop Guard is designed to prevent loops by keeping a port in a loop-inconsistent state, and native VLAN is related to VLAN tagging, not port state management.

Port security and EtherChannel do not directly address the need for a switch port to quickly transition to forwarding mode while also shutting down upon receiving a BPDU. Port security focuses on limiting MAC addresses and EtherChannel is used for link aggregation, neither of which fulfill the specific requirements of this question.

The current configuration uses access mode with voice vlan, which is correct for a phone+PC setup. Trunk mode is unnecessary and could break the phone's untagged traffic expectations.

The voice vlan is correctly configured for the phone; the problem is with the data vlan assignment for the desktop.

Portfast is beneficial for host ports; disabling it would worsen the issue by introducing STP convergence delays.

APs use Ethernet frames, not PPP encapsulation; PPP is used for serial links.

CAPWAP does not assign IP addresses; DHCP handles that, but removing the AP's IP does not correct the gateway mismatch.

Disabling DHCP on the controller would break all APs, not just AP-22, and does not address the gateway issue.

The native VLAN being missing would not directly cause a port to go err-disabled when connecting an IP phone and workstation; it typically results in VLAN mismatches or communication issues rather than disabling the port.

BPDU Guard is designed to protect against loops by disabling ports that receive Bridge Protocol Data Units (BPDUs). In this scenario, the port is err-disabled due to port security violations, not because of BPDU Guard activation.

DHCP snooping denying the voice VLAN would typically result in the IP phone failing to receive an IP address, rather than causing the port to go err-disabled. The err-disabled state is more likely due to port security violations when multiple devices are connected.

Root Guard prevents a port from being elected as root port, not from receiving BPDUs on an access port.

Loop Guard prevents loops caused by BPDU loss on blocked ports, not from BPDU reception on access ports.

UDLD detects unidirectional links but does not disable a port when a BPDU is received.

Load-balancing configuration does not influence the bundle state of a port-channel; it only affects frame distribution. The output shows a physical/logical inconsistency, not a hashing algorithm problem.

A common misconception is that any down or suspended link indicates an STP loop. However, 'show etherchannel detail' presents the explicit reason, and the native VLAN mismatch line directly contradicts this option.

The specific factual error is that trunk ports are used to carry multiple VLANs between switches, not for connecting end devices like phones and PCs. The correct method is to use an access port with a voice VLAN.

The specific factual error is that 'power inline never' explicitly disables PoE, which would prevent the phone from powering on. The correct command is 'power inline auto' to enable PoE detection and delivery.

The specific factual error is that the VLAN numbers are reversed. The access VLAN should be the data VLAN (10), and the voice VLAN should be 20. Swapping them would place data traffic in VLAN 20 and voice in VLAN 10, which is not the intended configuration.

EtherChannel is a technology used to combine multiple physical links into a single logical link for increased bandwidth and redundancy, but it does not separate user and voice traffic on a switchport. Therefore, it does not fulfill the requirement of carrying voice and user traffic separately.

SPAN (Switched Port Analyzer) is used for monitoring and capturing traffic on a switch port, not for separating user and voice traffic. It does not provide the necessary functionality to handle VLANs for voice and data traffic on a single port.

The Native VLAN is used for untagged traffic on a trunk port and does not separate voice and user traffic on an access port. It is not designed to handle the specific requirements of carrying both voice and data traffic separately.

The 'switchport protected' command is used to isolate ports within a VLAN (private VLAN edge), preventing communication between protected ports. It does not limit MAC addresses or trigger port shutdown upon violation.

The 'switchport nonegotiate' command disables Dynamic Trunking Protocol (DTP) negotiation, preventing the port from becoming a trunk. It does not limit MAC addresses or enforce violation actions, so it cannot meet the requirement to learn one MAC and shut down on a second unauthorized device.

Incorrect. OSPF router IDs are relevant to routing protocols and do not affect wireless client authentication or SSID association processes.

Incorrect. Routed-port mismatches on switch uplinks affect wired network traffic forwarding but do not cause wireless authentication failures at the client level.

Incorrect. DHCP relay problems affect IP address assignment after authentication; since the client fails authentication repeatedly, DHCP issues are not the cause.

The native VLAN must match the VLAN that the router's subinterface handles as untagged. Setting it to VLAN 1 violates the requirement.

The trunk must carry all VLANs that need inter-VLAN communication. Excluding VLAN 10 prevents its traffic from reaching the router.

PCs are end devices that expect untagged frames; they should be connected to access ports, not trunk ports.

LACP passive is not incompatible with LACP active.

PAgP/LACP mismatch leads to suspended state, not down; the exhibit's (D) indicates the link is not up, which points to LACP negotiation failure rather than protocol mismatch.

LACP negotiation is independent of the access/trunk configuration.