Infrastructure

ENCOR · 90 questions

• A city IT team wants the access-to-distribution link to carry multiple civic VLANs as an 802.1Q trunk, but staff keep seeing unexpected dynamic trunk negotiation after switch replacements. Which approach best removes that surprise while keeping a stable trunk?
• Courts distribution and access switches share an 802.1Q trunk, but untagged CDP and control traffic behave oddly after a closet rebuild. Engineers discover the native VLAN numbers differ on each end of the trunk. What is the most accurate description of that problem?
• Library stacks try to bundle two uplinks into an EtherChannel: one switch is set to LACP active and the peer ports are set to static ON mode. The Port-Channel never comes up as expected. What is the primary reason?
• Transit distribution builds a Port-Channel toward the fare-collection system, yet a single large TCP flow still saturates one member link. What limitation of EtherChannel load balancing best explains this?
• A school district wants edge access ports to err-disable if someone plugs in a rogue switch that starts sending BPDUs. Which feature best matches that requirement?
• Parks and Recreation places the STP root on distribution and wants designated ports toward wiring closets to refuse a superior BPDU from a downstream switch trying to become root. Which feature addresses that goal?
• City Hall migrates closets from classic 802.1D STP to Rapid-PVST+ after long reconvergence during switch failures. What is the main operational benefit they should expect?
• A convention center campus carries dozens of VLANs and wants fewer STP instances than per-VLAN Rapid-PVST+. Which technology best matches that goal?
• A police department closet accidentally trunks a user-facing port after a cable move, and investigators blame dynamic trunk negotiation. What is the best hardening practice for those user ports?
• At a water treatment plant, one physical member of an EtherChannel fails while the remaining members stay up. What should operators expect for traffic that still hashes to healthy members?
• A municipal hospital suddenly sees an access uplink move to a blocking role after a new switch is introduced in a closet ring. What STP concept best explains why a previously forwarding path may block?
• Airport operations notices the luggage-handling VLAN no longer passes on a trunk after a maintenance window. CDP neighbors still appear. Which trunk check is the most likely next step?
• A housing authority wants deterministic LACP negotiation on distribution uplinks so the channel forms even if the peer is passive. Which LACP role pairing best meets that intent?
• A 911 PSAP wants host-facing ports to come up quickly for workstations yet still shut down if a BPDU appears. Which combination best expresses that intent?
• A city museum ring of switches runs RSTP with one elected root. A non-root switch has a port that provides a backup path toward the root but does not forward. Which RSTP port role is that?
• Sanitation yard technicians cross-connect two closet switches with two ordinary access links and forget to build an EtherChannel. What prevents a Layer-2 loop from melting the yard network?
• County clerk switches are intended to share one MST region, but VLAN-to-instance mapping looks inconsistent after a partial config push. Which requirement is essential for switches to remain in the same MST region?
• After a fire-station access switch replacement, an uplink unexpectedly becomes a trunk via DTP even though the design called for a static access handoff to a phone closet device. What is the best corrective action?
• A municipal stadium aggregates two 10-Gbps distribution uplinks from an access switch into one logical Port-Channel. What primary benefit does that EtherChannel pattern provide?
• At a voter registration office, Root Guard is enabled on a distribution port toward an access switch. The access switch suddenly advertises a superior bridge ID. What is Root Guard’s expected local reaction?
• Public works engineers finish an MST deployment and must confirm voice and data VLANs follow the intended MST instances. What should they verify first?
• City fleet garage trunks flap with CDP and spanning-tree oddities after one side tags the native VLAN and the other still expects classic untagged native behavior. Which troubleshooting family does this fall into?
• County WAN engineers compare EIGRP’s composite metric and DUAL behavior with OSPF’s cost-based SPF on civic WAN routers. Which comparison is most accurate at ENCOR depth?
• City Hall wants unequal-cost multipath awareness historically associated with EIGRP, not only equal-cost paths. How does that differ from classic OSPF behavior?
• Transit OCC routers on a shared Ethernet segment fail to form a stable OSPF adjacency after one side is set to point-to-point and the other remains broadcast. What is the most likely impact of that network-type mismatch?
• A school district runs multi-area OSPF and wants campus prefixes summarized toward the WAN so area routers carry fewer Type-3 LSAs. Where should the engineer place that summarization?
• Police HQ must keep a jail VLAN's prefixes from being advertised campus-wide through OSPF while still routing inside the jail area. Which approach matches that inter-area filtering goal?
• A city library wants OSPF to advertise user VLAN subnets from SVIs without sending hellos or forming adjacencies on those access-facing interfaces. Which feature meets that requirement?
• An airport edge router forms eBGP with an ISP on a directly connected interface. Which neighbor relationship expectation is correct for that ENCOR-scoped design?
• A port authority sees two ISP paths in eBGP and needs to understand how the router chooses a single best path at ENCOR depth. Which statement is accurate?
• A water utility must steer traffic matching an extended ACL toward a scrubbing path instead of following destination-based routing alone. Which feature describes that capability?
• Courts IT is building multi-area OSPF with several normal areas for civic buildings. Which backbone rule must the design obey?
• Housing authority engineers compare how EIGRP and OSPF compute loop-free paths after a topology change. Which contrast is correct at ENCOR depth?
• A municipal hospital closet is dual-stack and must run OSPF for both IPv4 and IPv6. Which pairing correctly describes the protocol roles?
• City WAN staff configure eBGP multihop toward an ISP even though the neighbor is on the same directly connected subnet. What is the correct ENCOR expectation for that adjacency?
• Parks HQ wants guest-subnet traffic forced through a firewall path while staff traffic continues to follow normal destination routing. Which tool fits that selective steering use-case?
• A 911 PSAP reports an OSPF adjacency that never reaches FULL between two routers on a shared Ethernet segment. Timers show mismatched hello and dead intervals. What should the engineer conclude?
• Sanitation networking staff hear EIGRP terms reported distance and feasible distance and ask how that vocabulary differs from OSPF. Which statement is correct?
• A stadium ABR summarizes campus prefixes toward other OSPF areas. After a link failure inside the summarized range, remote routers no longer see more-specific prefixes. What trade-off should engineers expect?
• A ferry terminal runs stable single-area OSPF today and is adding a second campus that should not share a full identical LSDB with the terminal. When is introducing another normal area appropriate?
• A community college edge uses eBGP to two providers and wants outbound traffic to prefer one ISP using a well-known BGP best-path attribute. Which attribute awareness matches ENCOR depth for that goal?
• Animal services connects several OSPF routers on a broadcast Ethernet segment and sees a designated router and backup designated router elected. What is the purpose of that election?
• City planning needs a temporary construction-trailer subnet steered to a specific inspection firewall without redesigning the entire destination-based routing policy. Which description of PBR fits?
• County jail engineers must stop evidence-VLAN prefixes from leaking through OSPF toward a guest edge while keeping other jail routes. Which action aligns with simple OSPF prefix filtering?
• Fire/EMS dual-homes to two ISPs with eBGP for civic Internet. Within ENCOR scope, which neighbor pattern is the expected model?
• Museum campus engineers compare how EIGRP and OSPF react when a successor path disappears. Which operational contrast is accurate?
• A public library Ethernet WAN-style link between two routers should avoid DR/BDR election while still running OSPF. Which network-type choice fits that goal?
• Voter registration SVIs are configured as OSPF passive interfaces. What behavior should the team expect?
• City fleet garage applies PBR with a route-map. Traffic that does not match a permit clause falls through. How is that unmatched traffic forwarded?
• A wastewater plant should sit in its own OSPF normal area while remaining part of the city's multi-area design. Which attachment pattern is correct?
• A city stadium survey finds clients near the scoreboard report low SNR despite moderate RSSI. Which RF interpretation should the wireless engineer apply?
• A county library basement shows weak client RSSI. Staff propose raising AP transmit power and adding APs. Which RF concept pairing is most relevant?
• An airport remote concourse needs locally switched user traffic if the WAN to the central WLC is impaired. Which AP mode best matches that requirement?
• A courthouse needs focused coverage down a long corridor without spraying RF into adjacent courtrooms. Which antenna choice fits best?
• A school district AP fails to join its WLC. Engineers review CAPWAP discovery paths including DHCP and DNS. Which statement best describes the join principle?
• Police body-worn camera carts roam across floors that remain in the same VLAN versus carts that move onto a different subnet in another building. Which roaming distinction matters?
• City hall reports a WLAN client that will not authenticate. Per ENCOR emphasis, which troubleshooting approach should staff prioritize first on the WLC?
• A convention center must keep exhibit-floor guest WLANs policy-separated from staff WLANs on the same AP hardware. Which wireless construct set addresses that segmentation?
• Ferry terminal Wi-Fi suffers intermittent interference resembling strong non-Wi-Fi noise on a crowded band. Which RF planning response is most appropriate?
• A hospital AP is configured with primary and secondary WLC entries. After the primary fails, which join behavior should operations expect?
• Parks and recreation needs outdoor coverage focused toward a picnic pavilion rather than broadcasting equally in all directions. Which antenna approach fits?
• A community college WLAN mixes legacy clients with modern Wi-Fi 6 devices in the same BSS. Which planning concern is most accurate?
• A 911 PSAP needs seamless wireless mobility for devices that move between buildings on different IP subnets. Which roaming requirement applies?
• A museum runs guest and staff SSIDs on the same APs but needs different WLAN policies. Which approach aligns with ENCOR wireless segmentation?
• A sanitation yard AP remains stuck in discovery and never joins. The DHCP scope lacks the option that provides WLC addressing. Which discovery insight is correct?
• City council chambers need high client-count WLAN service from APs that still terminate CAPWAP to a WLC. Which mode concept is appropriate?
• A housing authority client associates to the WLAN but fails to obtain a DHCP address afterward. Using WLC GUI-oriented troubleshooting, what should engineers examine?
• A port authority wants wireless roam domains designed so devices stay on the same subnet across a contiguous terminal whenever possible. Which principle applies?
• An animal shelter Wi-Fi survey records RSSI and noise floor readings at a kennel doorway. How should engineers relate these to SNR?
• A voter registration center maps APs into the correct policy set for that building. Which wireless construct primarily binds APs to a site’s policy set in modern controller architectures?
• A fire training tower needs APs that actually serve firefighter tablet clients, not merely scan the air. Which AP mode concept is correct?
• City Wi-Fi GUI shows a client marked excluded after repeated auth failures. How should engineers interpret that during connectivity troubleshooting?
• Court IT must interpret device NTP lines so syslog timestamps align after an incident. A router shows it is synchronized to an upstream NTP server. Which interpretation is correct?
• A transit operations center evaluates timing for signaling gear that needs sub-microsecond synchronization. Which IP services comparison is appropriate?
• City staff on RFC1918 interiors browse the Internet through one public address. Which NAT behavior provides that many-to-one translation?
• A city library needs to publish an internal catalog server so remote patrons reach it on a fixed public address. Which NAT approach best matches that inbound publish requirement?
• Police access VLANs need a resilient default gateway so desktop cameras keep forwarding if one distribution switch fails. What is HSRP’s primary purpose in that design?
• A water utility edge mixes Cisco and another vendor’s routers and must keep a standards-based first-hop redundancy protocol. Which choice best fits that multi-vendor constraint?
• Stadium multicast video uses PIM and IGMP, but one camera stream is dropped when RPF checks fail on a distribution router. What does a successful RPF check verify before forwarding that multicast?
• School IPTV receivers must signal which multicast groups (and, when needed, which sources) they want while the LAN uses IGMP snooping with PIM upstream. Which statement best describes IGMPv2/v3’s role?
• A municipal hospital wants multicast clinical imaging to follow PIM sparse-mode concepts at ENCOR describe depth. What is PIM-SM’s core role in that design?
• A 911 PSAP must keep trusted time so incident logs stay aligned. When interpreting NTP choices at ENCOR depth, which practice best supports a secure, reliable time source?
• Passenger Wi-Fi at the airport suddenly cannot open new sessions while existing long-lived flows still pass. Engineers suspect the PAT pool is exhausted. Which symptom best matches that NAT condition?
• After a parks distribution switch reboots, staff want the higher-priority HSRP router to reclaim active forwarding without waiting for the current active to fail. Which concept enables that behavior?
• County jail endpoints should use one stable default-gateway address while two routers provide VRRP redundancy. Which address should those endpoints configure as their gateway?
• City hall applies a multicast boundary that unexpectedly stops needed PIM traffic toward a civic venue. What is the most accurate impact of that boundary?
• Convention-center engineers interpret NTP status and see a stratum value on a boundary clock. What does that stratum number primarily indicate?
• Sanitation publishes a SCADA historian reverse proxy with a permanent public mapping. Which NAT type best matches that one-to-one inbound publish use-case?
• A community-college switch floods IPTV to every port until IGMP snooping is enabled. What problem does IGMP snooping primarily solve?
• Emergency management needs separate resilient gateways for data and voice VLANs on the same distribution pair. Which HSRP approach best fits?