Topic 07 Practice Test 1 covers Discovery, EtherChannel, and Rapid PVST+ for Cisco Certified Network Associate 200-301 CCNA and maps to objectives 2.3–2.5. For broader exam preparation, review the Cisco CCNA 200-301 Exam Dumps. Every option includes focused technical reasoning explaining both the networking concept and its fit to the scenario.
Question 1
Aster is troubleshooting a Cisco-only access layer and wants to identify the directly connected Cisco device, including platform and port details. Which protocol is the most direct fit? Choose ONE.
- RSTP
- CDP
- LLDP
- LACP
Correct Answer: B
Correct Answer
Answer B is correct because Cisco Discovery Protocol (CDP) is Cisco-proprietary and advertises identity, platform, and port information to directly connected Cisco neighbors. At Aster, Cisco discovery evidence is checked directly. The CDP choice at Aster therefore meets the required outcome. At Aster, the Cisco discovery state is observable afterward.
Incorrect Answers
Answer C is incorrect because Link Layer Discovery Protocol (LLDP) is an IEEE vendor-neutral discovery protocol and is preferable in multivendor environments, but it is not Cisco’s proprietary mechanism. At Aster, Cisco discovery evidence is checked directly. The LLDP choice at Aster therefore misses the required outcome. At Aster, the Cisco discovery state is observable afterward.
Answer D is incorrect because Link Aggregation Control Protocol (LACP) negotiates EtherChannel membership and does not perform general neighbor discovery. At Aster, Cisco discovery evidence is checked directly. The LACP choice at Aster therefore misses the required outcome. At Aster, the Cisco discovery state is observable afterward.
Answer A is incorrect because Rapid Spanning Tree Protocol (RSTP) prevents Layer 2 loops and elects spanning-tree roles; it is not used to inventory adjacent devices. At Aster, Cisco discovery evidence is checked directly. The RSTP choice at Aster therefore misses the required outcome. At Aster, the Cisco discovery state is observable afterward.
Question 2
Delta connects a Cisco switch to a third-party switch and needs standards-based Layer 2 neighbor discovery. Which protocol should be used? Choose ONE.
- CDP
- PAgP
- LLDP
- DTP
Correct Answer: C
Correct Answer
Answer C is correct because LLDP is the IEEE 802.1AB standards-based neighbor discovery protocol and is designed to exchange device and port information across vendor boundaries. At Delta, multivendor discovery evidence is checked directly. The LLDP choice at Delta therefore meets the required outcome. At Delta, the multivendor discovery state is observable afterward.
Incorrect Answers
Answer A is incorrect because CDP is useful between Cisco devices but is Cisco-proprietary, so it is not the standards-based choice required for a multivendor link. At Delta, multivendor discovery evidence is checked directly. The CDP choice at Delta therefore misses the required outcome. At Delta, the multivendor discovery state is observable afterward.
Answer D is incorrect because Dynamic Trunking Protocol (DTP) negotiates switchport trunking and does not advertise general neighbor inventory information. At Delta, multivendor discovery evidence is checked directly. The DTP choice at Delta therefore misses the required outcome. At Delta, the multivendor discovery state is observable afterward.
Answer B is incorrect because Port Aggregation Protocol (PAgP) is a Cisco-proprietary EtherChannel negotiation protocol rather than a general discovery protocol. At Delta, multivendor discovery evidence is checked directly. The PAgP choice at Delta therefore misses the required outcome. At Delta, the multivendor discovery state is observable afterward.
Question 3
Granite needs the management IP address and remote port identifier of a directly connected Cisco neighbor. Which command is most likely to provide the detailed information? Choose ONE.
- show lldp traffic
- show etherchannel summary
- show spanning-tree
- show cdp neighbors detail
Correct Answer: D
Correct Answer
Answer D is correct because `show cdp neighbors detail` expands CDP neighbor information and commonly includes management addressing plus platform, interface, and capability details. At Granite, CDP detail evidence is checked directly. The show cdp choice at Granite therefore meets the required outcome. At Granite, the CDP detail state is observable afterward.
Incorrect Answers
Answer A is incorrect because `show lldp traffic` focuses on LLDP message counters and does not provide the requested detailed CDP neighbor record. At Granite, CDP detail evidence is checked directly. The show lldp choice at Granite therefore misses the required outcome. At Granite, the CDP detail state is observable afterward.
Answer B is incorrect because `show etherchannel summary` reports port-channel membership and state, not CDP management addressing for an adjacent device. At Granite, CDP detail evidence is checked directly. The show etherchannel choice at Granite therefore misses the required outcome. At Granite, the CDP detail state is observable afterward.
Answer C is incorrect because `show spanning-tree` reports spanning-tree topology and port roles rather than detailed device discovery information. At Granite, CDP detail evidence is checked directly. The show spanning-tree choice at Granite therefore misses the required outcome. At Granite, the CDP detail state is observable afterward.
Question 4
Mesa is building an EtherChannel between two Cisco switches using the IEEE negotiation protocol. Which protocol should be selected? Choose ONE.
- DTP
- LACP
- PAgP
- CDP
Correct Answer: B
Correct Answer
Answer B is correct because LACP is the standards-based Link Aggregation Control Protocol used to negotiate and maintain bundled links in an EtherChannel. At Mesa, LACP standard evidence is checked directly. The LACP choice at Mesa therefore meets the required outcome. At Mesa, the LACP standard state is observable afterward.
Incorrect Answers
Answer C is incorrect because PAgP can negotiate an EtherChannel on Cisco equipment, but it is Cisco-proprietary and therefore does not meet the standards-based requirement. At Mesa, LACP standard evidence is checked directly. The PAgP choice at Mesa therefore misses the required outcome. At Mesa, the LACP standard state is observable afterward.
Answer A is incorrect because DTP negotiates Layer 2 trunk mode and is independent of whether parallel links are bundled into an EtherChannel. At Mesa, LACP standard evidence is checked directly. The DTP choice at Mesa therefore misses the required outcome. At Mesa, the LACP standard state is observable afterward.
Answer D is incorrect because CDP discovers directly connected Cisco devices but does not negotiate aggregate link membership. At Mesa, LACP standard evidence is checked directly. The CDP choice at Mesa therefore misses the required outcome. At Mesa, the LACP standard state is observable afterward.
Question 5
Pioneer configures one side of an LACP EtherChannel as `channel-group 5 mode active`. Which peer mode will successfully negotiate the bundle while remaining passive? Choose ONE.
- auto on one side and desirable on the other
- on on one side and passive on the other
- active on one side and passive on the other
- passive on both sides
Correct Answer: C
Correct Answer
Answer C is correct because An LACP active interface initiates negotiation, while a passive interface responds; active/passive is therefore a valid LACP pairing. At Pioneer, active passive LACP evidence is checked directly. The active on choice at Pioneer therefore meets the required outcome. At Pioneer, the active passive LACP state is observable afterward.
Incorrect Answers
Answer D is incorrect because Two passive LACP interfaces wait for the peer to initiate, so negotiation does not begin and the bundle will not form through LACP. At Pioneer, active passive LACP evidence is checked directly. The passive on choice at Pioneer therefore misses the required outcome. At Pioneer, the active passive LACP state is observable afterward.
Answer A is incorrect because `auto` and `desirable` are PAgP modes, not LACP modes, so that pair does not satisfy an LACP requirement. At Pioneer, active passive LACP evidence is checked directly. The auto on choice at Pioneer therefore misses the required outcome. At Pioneer, the active passive LACP state is observable afterward.
Answer B is incorrect because Static `on` does not negotiate with LACP; mixing static-on behavior with LACP passive does not create the intended negotiated bundle. At Pioneer, active passive LACP evidence is checked directly. The on on choice at Pioneer therefore misses the required outcome. At Pioneer, the active passive LACP state is observable afterward.
Question 6
Summit configures both ends of a new LACP bundle as passive. The member links remain individual. What is the most direct correction? Choose ONE.
- Change at least one side to LACP active
- Change both sides to PAgP auto
- Enable PortFast on all members
- Configure a native VLAN on the port-channel
Correct Answer: A
Correct Answer
Answer A is correct because At least one side must be LACP active so negotiation is initiated; the other side may remain passive and respond. At Summit, passive LACP evidence is checked directly. The Change at choice at Summit therefore meets the required outcome. At Summit, the passive LACP state is observable afterward.
Incorrect Answers
Answer B is incorrect because PAgP auto is a different aggregation protocol and changing both sides to auto would still leave both peers waiting rather than meeting the LACP design. At Summit, passive LACP evidence is checked directly. The Change both choice at Summit therefore misses the required outcome. At Summit, the passive LACP state is observable afterward.
Answer C is incorrect because PortFast affects spanning-tree behavior and does not cause passive LACP peers to initiate link-aggregation negotiation. At Summit, passive LACP evidence is checked directly. The Enable PortFast choice at Summit therefore misses the required outcome. At Summit, the passive LACP state is observable afterward.
Answer D is incorrect because A native VLAN may matter on a trunked port-channel but it has no role in starting LACP negotiation between two passive endpoints. At Summit, passive LACP evidence is checked directly. The Configure a choice at Summit therefore misses the required outcome. At Summit, the passive LACP state is observable afterward.
Question 7
Beacon’s four intended EtherChannel members use the same channel group, but one member is configured as an access port while the others are trunks. What should be corrected first? Choose ONE.
- Configure independent IP addresses on every Layer 2 member
- Make the member interface Layer 2 settings consistent with the rest of the bundle
- Give each member a different native VLAN to identify it
- Assign a different access VLAN to each member for load balancing
Correct Answer: B
Correct Answer
Answer B is correct because EtherChannel members must have compatible Layer 2 characteristics such as switchport mode and VLAN parameters; inconsistent configuration can prevent or suspend bundling. At Beacon, member consistency evidence is checked directly. The Make the choice at Beacon therefore meets the required outcome. At Beacon, the member consistency state is observable afterward.
Incorrect Answers
Answer C is incorrect because Using different native VLANs on members creates inconsistent trunk behavior and is not a valid way to identify or load-balance EtherChannel links. At Beacon, member consistency evidence is checked directly. The Give each choice at Beacon therefore misses the required outcome. At Beacon, the member consistency state is observable afterward.
Answer D is incorrect because Different access VLANs on members are incompatible with a single logical Layer 2 port-channel and can prevent the interfaces from joining correctly. At Beacon, member consistency evidence is checked directly. The Assign a choice at Beacon therefore misses the required outcome. At Beacon, the member consistency state is observable afterward.
Answer A is incorrect because Layer 2 EtherChannel members do not each receive independent routed IP addresses; Layer 3 addressing belongs on the port-channel interface when building a routed channel. At Beacon, member consistency evidence is checked directly. The Configure independent choice at Beacon therefore misses the required outcome. At Beacon, the member consistency state is observable afterward.
Question 8
Ember has a Layer 2 EtherChannel operating as a trunk. Where should VLAN trunk settings normally be applied for consistent bundle behavior? Choose ONE.
- The switch’s management SVI
- Every member with intentionally different VLAN lists
- The Port-channel interface
- Only the lowest-numbered physical member
Correct Answer: C
Correct Answer
Answer C is correct because The Port-channel is the logical interface for the bundle, so shared Layer 2 trunk policy should be applied consistently to that logical interface rather than creating member mismatches. At Ember, logical port-channel evidence is checked directly. The The Port-channel choice at Ember therefore meets the required outcome. At Ember, the logical port-channel state is observable afterward.
Incorrect Answers
Answer D is incorrect because Applying policy only to one physical link can leave the aggregate members inconsistent and does not represent the bundle as one logical link. At Ember, logical port-channel evidence is checked directly. The Only the choice at Ember therefore misses the required outcome. At Ember, the logical port-channel state is observable afterward.
Answer B is incorrect because Intentionally different VLAN lists defeat member consistency and can prevent correct EtherChannel operation. At Ember, logical port-channel evidence is checked directly. The Every member choice at Ember therefore misses the required outcome. At Ember, the logical port-channel state is observable afterward.
Answer A is incorrect because An SVI provides Layer 3 service for a VLAN and is unrelated to configuring the trunk behavior of the EtherChannel itself. At Ember, logical port-channel evidence is checked directly. The The switch’s choice at Ember therefore misses the required outcome. At Ember, the logical port-channel state is observable afterward.
Question 9
Harbor needs a routed EtherChannel between two multilayer switches. Which design places the Layer 3 address correctly? Choose ONE.
- Use `switchport trunk native vlan` as the Layer 3 address
- Configure `no switchport` as appropriate and put the IP address on the Port-channel interface
- Keep the members as access ports and put the IP address on VLAN 1
- Place a different IP address on every physical member
Correct Answer: B
Correct Answer
Answer B is correct because A routed EtherChannel operates as one logical Layer 3 interface; the port-channel is configured for routed operation and carries the IP address for the aggregate. At Harbor, routed EtherChannel evidence is checked directly. The Configure no choice at Harbor therefore meets the required outcome. At Harbor, the routed EtherChannel state is observable afterward.
Incorrect Answers
Answer D is incorrect because Independent addresses on physical members treat them as separate Layer 3 links rather than one logical EtherChannel and conflict with the intended aggregate interface. At Harbor, routed EtherChannel evidence is checked directly. The Place a choice at Harbor therefore misses the required outcome. At Harbor, the routed EtherChannel state is observable afterward.
Answer C is incorrect because An access-port/VLAN 1 design is Layer 2 switching and does not create the requested routed point-to-point port-channel. At Harbor, routed EtherChannel evidence is checked directly. The Keep the choice at Harbor therefore misses the required outcome. At Harbor, the routed EtherChannel state is observable afterward.
Answer A is incorrect because A native-VLAN command configures 802.1Q trunk behavior and is unrelated to assigning a Layer 3 IP address to a routed EtherChannel. At Harbor, routed EtherChannel evidence is checked directly. The Use switchport choice at Harbor therefore misses the required outcome. At Harbor, the routed EtherChannel state is observable afterward.
Question 10
Keystone wants a concise view of EtherChannel groups, negotiation protocol, and whether member ports are bundled. Which command is most useful? Choose ONE.
- show etherchannel summary
- show cdp traffic
- show interfaces trunk
- show spanning-tree root
Correct Answer: A
Correct Answer
Answer A is correct because `show etherchannel summary` presents port-channel groups, protocols, logical-channel state, and member-interface flags, making it the direct bundle-verification command. At Keystone, EtherChannel summary evidence is checked directly. The show etherchannel choice at Keystone therefore meets the required outcome. At Keystone, the EtherChannel summary state is observable afterward.
Incorrect Answers
Answer C is incorrect because `show interfaces trunk` can show a port-channel if it is trunking, but it does not provide the same member-level EtherChannel negotiation and bundling summary. At Keystone, EtherChannel summary evidence is checked directly. The show interfaces choice at Keystone therefore misses the required outcome. At Keystone, the EtherChannel summary state is observable afterward.
Answer D is incorrect because `show spanning-tree root` focuses on root information and does not identify whether intended physical links are successfully bundled. At Keystone, EtherChannel summary evidence is checked directly. The show spanning-tree choice at Keystone therefore misses the required outcome. At Keystone, the EtherChannel summary state is observable afterward.
Answer B is incorrect because `show cdp traffic` shows discovery-protocol counters rather than EtherChannel member and port-channel state. At Keystone, EtherChannel summary evidence is checked directly. The show cdp choice at Keystone therefore misses the required outcome. At Keystone, the EtherChannel summary state is observable afterward.
Question 11
Northstar needs to predict the Rapid PVST+ root bridge for VLAN 20. Which device wins the election? Choose ONE.
- The switch with the highest MAC address
- The first switch to boot
- The switch with the greatest root-path cost
- The switch with the lowest bridge ID
Correct Answer: D
Correct Answer
Answer D is correct because Spanning tree elects the root bridge using the lowest bridge ID, which incorporates bridge priority and a MAC-derived component for tie breaking. At Northstar, root election evidence is checked directly. The The switch choice at Northstar therefore meets the required outcome. At Northstar, the root election state is observable afterward.
Incorrect Answers
Answer A is incorrect because A higher MAC address does not win; when priorities tie, the lower bridge identifier component is favored. At Northstar, root election evidence is checked directly. The The switch choice at Northstar therefore misses the required outcome. At Northstar, the root election state is observable afterward.
Answer C is incorrect because Root-path cost is used by non-root switches to select paths toward the elected root, not to elect the root bridge itself. At Northstar, root election evidence is checked directly. The The switch choice at Northstar therefore misses the required outcome. At Northstar, the root election state is observable afterward.
Answer B is incorrect because Boot order does not define the stable root-election rule; bridge ID comparison determines the elected root. At Northstar, root election evidence is checked directly. The The first choice at Northstar therefore misses the required outcome. At Northstar, the root election state is observable afterward.
Question 12
Quartz’s access switch has two paths toward the Rapid PVST+ root. Which local port becomes the root port? Choose ONE.
- The port with the highest interface number
- Every forwarding port becomes a root port
- The port that most recently received a data frame
- The port with the lowest root-path cost toward the root
Correct Answer: D
Correct Answer
Answer D is correct because A non-root switch chooses one root port representing its best path to the root bridge; root-path cost is a primary comparison in that selection process. At Quartz, root-port selection evidence is checked directly. The The port choice at Quartz therefore meets the required outcome. At Quartz, the root-port selection state is observable afterward.
Incorrect Answers
Answer A is incorrect because Interface numbering is not the fundamental spanning-tree path-selection rule and a higher number does not automatically become the root port. At Quartz, root-port selection evidence is checked directly. The The port choice at Quartz therefore misses the required outcome. At Quartz, the root-port selection state is observable afterward.
Answer B is incorrect because A switch has one root port per spanning-tree instance, while other forwarding interfaces can be designated ports. At Quartz, root-port selection evidence is checked directly. The Every forwarding choice at Quartz therefore misses the required outcome. At Quartz, the root-port selection state is observable afterward.
Answer C is incorrect because User data arrival timing does not determine the root-port election; BPDUs and spanning-tree path information do. At Quartz, root-port selection evidence is checked directly. The The port choice at Quartz therefore misses the required outcome. At Quartz, the root-port selection state is observable afterward.
Question 13
Tundra has two switches connected to the same Layer 2 segment. Which Rapid PVST+ role forwards the best path from that segment toward the root? Choose ONE.
- Alternate port
- Root port
- Designated port
- Disabled port
Correct Answer: C
Correct Answer
Answer C is correct because The designated port is elected for a Layer 2 segment and represents the best path from that segment toward the root; it normally forwards for that segment. At Tundra, designated-port role evidence is checked directly. The Designated port choice at Tundra therefore meets the required outcome. At Tundra, the designated-port role state is observable afterward.
Incorrect Answers
Answer B is incorrect because The root port is selected on each non-root bridge as that switch’s best path to the root, which is a different role from the per-segment designated port. At Tundra, designated-port role evidence is checked directly. The Root port choice at Tundra therefore misses the required outcome. At Tundra, the designated-port role state is observable afterward.
Answer A is incorrect because An alternate port provides a redundant path and normally remains in a discarding role rather than serving as the segment’s forwarding designated port. At Tundra, designated-port role evidence is checked directly. The Alternate port choice at Tundra therefore misses the required outcome. At Tundra, the designated-port role state is observable afterward.
Answer D is incorrect because A disabled port does not participate in spanning-tree forwarding or election for the segment. At Tundra, designated-port role evidence is checked directly. The Disabled port choice at Tundra therefore misses the required outcome. At Tundra, the designated-port role state is observable afterward.
Question 14
Cobalt’s Rapid PVST+ topology has a redundant link that offers an alternate route to the root and is currently discarding. Which port role best describes it? Choose ONE.
- Alternate port
- Edge port only
- Root port on the root bridge
- Designated port
Correct Answer: A
Correct Answer
Answer A is correct because An alternate port provides a redundant path toward the root and normally remains discarding until it is needed, enabling faster convergence when the active path fails. At Cobalt, alternate-port role evidence is checked directly. The Alternate port choice at Cobalt therefore meets the required outcome. At Cobalt, the alternate-port role state is observable afterward.
Incorrect Answers
Answer D is incorrect because A designated port is the selected forwarding port for a segment and is not the normal description of the blocked backup path in this scenario. At Cobalt, alternate-port role evidence is checked directly. The Designated port choice at Cobalt therefore misses the required outcome. At Cobalt, the alternate-port role state is observable afterward.
Answer B is incorrect because Edge/PortFast status describes an endpoint-facing convergence behavior and is not the spanning-tree role for a redundant infrastructure path. At Cobalt, alternate-port role evidence is checked directly. The Edge port choice at Cobalt therefore misses the required outcome. At Cobalt, the alternate-port role state is observable afterward.
Answer C is incorrect because The root bridge has no root port because it is the destination of root paths; therefore this cannot describe the redundant port shown. At Cobalt, alternate-port role evidence is checked directly. The Root port choice at Cobalt therefore misses the required outcome. At Cobalt, the alternate-port role state is observable afterward.
Question 15
Falcon asks which three operational states Rapid PVST+ uses for ports. Which answer is correct? Choose ONE.
- Blocking, listening, learning, forwarding, disabled
- Active, passive, on
- Discarding, learning, forwarding
- Down, testing, standby
Correct Answer: C
Correct Answer
Answer C is correct because Rapid STP consolidates non-forwarding behavior into discarding and uses the operational states discarding, learning, and forwarding. At Falcon, RSTP states evidence is checked directly. The Discarding, learning, choice at Falcon therefore meets the required outcome. At Falcon, the RSTP states state is observable afterward.
Incorrect Answers
Answer A is incorrect because The five-state blocking/listening/learning/forwarding/disabled model is associated with classic 802.1D terminology rather than the simplified Rapid STP state set. At Falcon, RSTP states evidence is checked directly. The Blocking, listening, choice at Falcon therefore misses the required outcome. At Falcon, the RSTP states state is observable afterward.
Answer B is incorrect because Active, passive, and on are link-aggregation negotiation/configuration terms, not Rapid PVST+ port states. At Falcon, RSTP states evidence is checked directly. The Active, passive, choice at Falcon therefore misses the required outcome. At Falcon, the RSTP states state is observable afterward.
Answer D is incorrect because Down, testing, and standby are not the standardized Rapid STP forwarding-state names used to describe convergence. At Falcon, RSTP states evidence is checked directly. The Down, testing, choice at Falcon therefore misses the required outcome. At Falcon, the RSTP states state is observable afterward.
Question 16
Ion connects a single-user workstation to Gi1/0/10 and wants the edge port to transition to forwarding without waiting through normal topology convergence. Which feature is appropriate? Choose ONE.
- LACP passive
- Root Guard
- PortFast
- Loop Guard
Correct Answer: C
Correct Answer
Answer C is correct because PortFast treats an interface as an edge port and allows it to transition rapidly to forwarding, which is appropriate for ports known to connect only to endpoints. At Ion, PortFast edge evidence is checked directly. The PortFast choice at Ion therefore meets the required outcome. At Ion, the PortFast edge state is observable afterward.
Incorrect Answers
Answer B is incorrect because Root Guard protects root placement by blocking a port that receives superior BPDUs; it does not primarily accelerate endpoint-port forwarding. At Ion, PortFast edge evidence is checked directly. The Root Guard choice at Ion therefore misses the required outcome. At Ion, the PortFast edge state is observable afterward.
Answer D is incorrect because Loop Guard protects against certain unidirectional or missing-BPDU conditions on non-designated paths and is not the edge-port acceleration feature. At Ion, PortFast edge evidence is checked directly. The Loop Guard choice at Ion therefore misses the required outcome. At Ion, the PortFast edge state is observable afterward.
Answer A is incorrect because LACP passive is an EtherChannel negotiation mode and has no role in Rapid PVST+ edge-port convergence. At Ion, PortFast edge evidence is checked directly. The LACP passive choice at Ion therefore misses the required outcome. At Ion, the PortFast edge state is observable afterward.
Question 17
Lumen enables PortFast on a user-facing port and also wants the port shut down if a switch is accidentally connected and sends BPDUs. Which feature should be paired with PortFast? Choose ONE.
- BPDU Guard
- Loop Guard
- Root Guard
- BPDU Filter
Correct Answer: A
Correct Answer
Answer A is correct because BPDU Guard protects edge/PortFast ports by placing the interface into an error-disabled condition when BPDUs are received, preventing an unexpected switch from joining the topology. At Lumen, BPDU Guard evidence is checked directly. The BPDU Guard choice at Lumen therefore meets the required outcome. At Lumen, the BPDU Guard state is observable afterward.
Incorrect Answers
Answer D is incorrect because BPDU Filter suppresses or filters BPDU transmission/reception depending on how it is configured; it is not the same fail-closed BPDU-reception behavior described. At Lumen, BPDU Guard evidence is checked directly. The BPDU Filter choice at Lumen therefore misses the required outcome. At Lumen, the BPDU Guard state is observable afterward.
Answer C is incorrect because Root Guard puts a port into root-inconsistent when superior BPDUs threaten root placement, rather than generally err-disabling an edge port on any BPDU. At Lumen, BPDU Guard evidence is checked directly. The Root Guard choice at Lumen therefore misses the required outcome. At Lumen, the BPDU Guard state is observable afterward.
Answer B is incorrect because Loop Guard protects against a blocked/root path incorrectly transitioning because expected BPDUs stop arriving, not against a new switch sending a BPDU on an edge port. At Lumen, BPDU Guard evidence is checked directly. The Loop Guard choice at Lumen therefore misses the required outcome. At Lumen, the BPDU Guard state is observable afterward.
Question 18
Orchid has a downstream customer switch that must never become the Rapid PVST+ root. Which feature should be enabled on the provider-facing port? Choose ONE.
- Root Guard
- PortFast
- Loop Guard
- BPDU Guard
Correct Answer: A
Correct Answer
Answer A is correct because Root Guard allows normal spanning-tree participation but places the port in root-inconsistent if superior BPDUs would cause that port to become a path toward an unauthorized root. At Orchid, Root Guard evidence is checked directly. The Root Guard choice at Orchid therefore meets the required outcome. At Orchid, the Root Guard state is observable afterward.
Incorrect Answers
Answer D is incorrect because BPDU Guard is normally used to protect edge ports and reacts to BPDU receipt by err-disabling the interface rather than enforcing root placement on a downstream switch link. At Orchid, Root Guard evidence is checked directly. The BPDU Guard choice at Orchid therefore misses the required outcome. At Orchid, the Root Guard state is observable afterward.
Answer C is incorrect because Loop Guard protects against loss of expected BPDUs on alternate/root paths; it is not designed to reject a downstream device that advertises a superior root. At Orchid, Root Guard evidence is checked directly. The Loop Guard choice at Orchid therefore misses the required outcome. At Orchid, the Root Guard state is observable afterward.
Answer B is incorrect because PortFast accelerates edge-port forwarding and should not be used as the mechanism for preventing a downstream switch from becoming root. At Orchid, Root Guard evidence is checked directly. The PortFast choice at Orchid therefore misses the required outcome. At Orchid, the Root Guard state is observable afterward.
Question 19
Redwood has an alternate spanning-tree port that could incorrectly transition to forwarding if BPDUs stop arriving because of a unidirectional failure. Which feature helps prevent that loop? Choose ONE.
- BPDU Guard
- Root Guard
- Loop Guard
- PortFast
Correct Answer: C
Correct Answer
Answer C is correct because Loop Guard monitors ports that should continue receiving BPDUs and can place them into a loop-inconsistent state rather than allowing an unsafe forwarding transition when BPDUs disappear. At Redwood, Loop Guard evidence is checked directly. The Loop Guard choice at Redwood therefore meets the required outcome. At Redwood, the Loop Guard state is observable afterward.
Incorrect Answers
Answer B is incorrect because Root Guard reacts to superior BPDUs that threaten root placement, which is a different failure condition from losing expected BPDUs on a redundant path. At Redwood, Loop Guard evidence is checked directly. The Root Guard choice at Redwood therefore misses the required outcome. At Redwood, the Loop Guard state is observable afterward.
Answer A is incorrect because BPDU Guard is commonly applied to edge ports and reacts when BPDUs are received, the opposite trigger from the missing-BPDU condition described. At Redwood, Loop Guard evidence is checked directly. The BPDU Guard choice at Redwood therefore misses the required outcome. At Redwood, the Loop Guard state is observable afterward.
Answer D is incorrect because PortFast accelerates edge convergence and does not provide the missing-BPDU protection required for an infrastructure redundancy path. At Redwood, Loop Guard evidence is checked directly. The PortFast choice at Redwood therefore misses the required outcome. At Redwood, the Loop Guard state is observable afterward.
Question 20
Aster considers enabling BPDU Filter on a switch-to-switch link to ‘make STP quieter.’ What is the primary risk? Choose ONE.
- It forces the local switch to become the root on every VLAN
- It encrypts BPDUs and breaks CDP only
- It automatically forms an EtherChannel with the neighbor
- Suppressing BPDUs can hide topology information and permit a Layer 2 loop
Correct Answer: D
Correct Answer
Answer D is correct because Spanning tree depends on BPDU exchange to calculate a loop-free topology; suppressing BPDUs on infrastructure links can hide redundant paths and allow forwarding loops. At Aster, BPDU Filter evidence is checked directly. The Suppressing BPDUs choice at Aster therefore meets the required outcome. At Aster, the BPDU Filter state is observable afterward.
Incorrect Answers
Answer A is incorrect because BPDU filtering does not deterministically force a switch to become root; root election still depends on bridge information seen by participating devices. At Aster, BPDU Filter evidence is checked directly. The It forces choice at Aster therefore misses the required outcome. At Aster, the BPDU Filter state is observable afterward.
Answer C is incorrect because BPDU Filter has no EtherChannel negotiation function and cannot form a link-aggregation bundle. At Aster, BPDU Filter evidence is checked directly. The It automatically choice at Aster therefore misses the required outcome. At Aster, the BPDU Filter state is observable afterward.
Answer B is incorrect because BPDU filtering concerns spanning-tree control messages; it does not encrypt BPDUs or operate as a CDP-specific security mechanism. At Aster, BPDU Filter evidence is checked directly. The It encrypts choice at Aster therefore misses the required outcome. At Aster, the BPDU Filter state is observable afterward.
