Cisco 300-420 Bundle

That change concerns diffserv versus intserv service model, where Per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments. The reported issue instead stems from: Policing enforces a rate by dropping or remarking excess packets, whereas shaping ordinarily smooths outbound bursts using buffers.

That change concerns voice priority queuing starvation, where An oversized or unbounded strict-priority queue can consume interface capacity and deny adequate service to other classes. In this question the necessary remedy is “Use shaping for traffic that can tolerate buffering and selective policing where a hard ingress contract is needed”, which this alternative does not provide.

That change concerns qos trust boundary at user access, where Trusting unvalidated endpoint DSCP markings allows unauthorized traffic to consume preferential network resources. The observed condition is a design uses aggressive ingress policing for interactive video and expects the policer to buffer all bursts until bandwidth becomes available; this mechanism addresses another problem.

An unprotected adjacency trust boundary can admit unauthorized IS-IS control messages into a routing domain. “Deploy supported IS-IS authentication with coordinated algorithms and keys and restrict peers to intended segments” would remedy that alternative situation, but it would not correct the present issue: translation adds stateful dependencies and application edge cases that may be unnecessary when a controlled native dual-stack phase is viable.

“Budget tunnel overhead in MTU planning, preserve required ICMPv6 control messages and validate endpoints' segment sizes” is the supported response when overlay headers reduce usable path MTU and blocked ICMPv6 Packet Too Big feedback can prevent Path MTU Discovery. Here the decisive response is “Select native dual stack for capable segments and reserve translation for real IPv4-only boundaries with documented requirements”, so that different intervention does not meet the stated requirement.

IPv6-only clients cannot communicate with IPv4-only services without supported translation and suitable destination synthesis. “Design appropriate NAT64 plus DNS64 service boundaries, DNS behavior and application compatibility exceptions” applies to that other condition. The reported evidence is a migration team proposes full NAT64 for an entire enterprise even though most applications and WAN devices already support IPv6 and IPv4 simultaneously; this alternative would address the wrong dependency.

Bandwidth alone does not determine application suitability when propagation delay and jitter exceed interactive service limits. “Test delay-sensitive applications on each planned failover path before approving WAN topology” would remedy that alternative situation, but it would not correct the present issue: mobile backup is useful only if real coverage, policy, cost and failure independence support required branch services.

“Document E-Line versus E-LAN service boundaries and operational responsibility with the provider” is the supported response when multipoint Ethernet services and many independent E-Line circuits have different Layer 2 forwarding and spanning-tree implications. Here the decisive response is “Verify seasonal radio performance and data-cap alarms before relying on cellular as a branch recovery path”, so that different intervention does not meet the stated requirement.

A shared provider routing domain cannot preserve independent overlapping tenant address spaces and route targets without isolation. “Audit route targets, route distinguishers and provider CE handoff details during onboarding and acquisitions” applies to that other condition. The reported evidence is a remote retail site uses a single fixed broadband circuit and proposes 5G backup without checking data caps, radio conditions or carrier diversity; this alternative would address the wrong dependency.

Conventional iBGP full mesh grows quadratically and becomes costly to configure, observe and recover. “Test reflection path diversity and redundant reflector failure modes before retiring full-mesh peers” would remedy that alternative situation, but it would not correct the present issue: unnecessary specific-route propagation increases state and change sensitivity without providing required central policy detail.

“Review maximum path and variance behavior during circuit upgrades and dual-WAN commissioning” is the supported response when EIGRP unequal-cost load sharing is not enabled simply because multiple routes exist and is constrained by feasibility and variance. Here the decisive response is “Require prefix allocation consistency before EIGRP summarization is enabled in production”, so that different intervention does not meet the stated requirement.

Uncontrolled bidirectional redistribution can reintroduce routes, create loops and lose source-of-truth route preference. “Audit redistribution route tags and policy match order whenever a new domain boundary is added” applies to that other condition. The reported evidence is a distribution router advertises every tiny branch prefix separately into the EIGRP core even though branches are allocated in contiguous blocks; this alternative would address the wrong dependency.

Physical link-up is insufficient to guarantee bidirectional signal integrity, which can affect control-plane protocols and forwarding. “Enable appropriate UDLD modes on supported fiber links and validate shutdown and recovery procedures” would remedy that alternative situation, but it would not correct the present issue: a non-designated STP port losing expected control messages can create a loop if it incorrectly assumes the superior path vanished.

“Enable Root Guard on appropriate downstream designated ports and keep intended root roles explicit” is the supported response when superior BPDUs on an untrusted downstream link can alter STP root selection unless the boundary is protected. Here the decisive response is “Use Loop Guard on appropriate non-edge STP links and deploy complementary unidirectional link detection where supported”, so that different intervention does not meet the stated requirement.

MST region membership requires consistent region identifier, revision and VLAN mapping rather than matching only some VLAN names. “Align approved MST region configuration and verify boundary ports and per-instance root placement” applies to that other condition. The reported evidence is one of two redundant STP links stops receiving BPDUs due to a unidirectional fault but remains physically up, risking a blocked port transitioning to forwarding; this alternative would address the wrong dependency.

That change concerns graceful restart campus routing continuity, where Routing graceful restart requires compatible neighbor capability and safe stale-route lifetimes, not merely redundant uplinks. The reported issue instead stems from: Traditional active-standby first-hop redundancy does not by itself provide the desired per-client gateway load distribution.

That change concerns hsrp split brain and vlan consistency, where FHRP peers must exchange control messages in a correctly shared VLAN to maintain a single active forwarding role. In this question the necessary remedy is “Consider GLBP where supported or a different routed access and anycast design, based on platform capability and operational needs”, which this alternative does not provide.

That change concerns hsrp default gateway resilience, where A single physical gateway address makes host access depend on one distribution device even when a second gateway exists. The observed condition is a large access VLAN needs multiple distribution gateways to forward client traffic concurrently, but the proposed HSRP design forwards all hosts through one active router; this mechanism addresses another problem.

That change concerns equal cost site routing load sharing, where Physical redundancy does not imply control-plane equal-cost path installation or useful flow distribution. The reported issue instead stems from: Without port security or identity-aware access control, a simple access port may learn multiple endpoint MAC addresses without limitation.

That change concerns multichassis link peer failure, where A conventional port channel cannot span unrelated independent switches without a supported multichassis or stacking mechanism. In this question the necessary remedy is “Deploy suitable port security or 802.1X/MAB policies with sensible violation and recovery handling for endpoint types”, which this alternative does not provide.

That change concerns campus poe power budgeting, where Available PoE power budget and per-port capabilities determine whether simultaneous endpoint power requirements can be met. The observed condition is a user port should admit one registered device but an unmanaged bridge with several MAC addresses is connected, and the switch admits all sources; this mechanism addresses another problem.

That change concerns sd access virtual network macro segmentation, where Security group policy alone may not replace full virtual-network level route isolation where separate macrosegments are required. The reported issue instead stems from: Fabric overlay multicast support and replication design have specific control and data-plane requirements beyond simple underlay multicast reachability.

That change concerns sd access cisco ise identity policy role, where Identity group classification requires a trusted policy source and onboarding process rather than arbitrary address-based role guessing. In this question the necessary remedy is “Select a supported SD-Access multicast forwarding model and test receivers across fabric edges and virtual networks”, which this alternative does not provide.

That change concerns sd access sgt micro segmentation, where IP-prefix ACLs become brittle when identity and endpoint groups move, while fabric policy can use scalable group-based classification. The observed condition is an enterprise uses multicast video across a campus fabric but assumes ordinary underlay PIM subscriptions automatically deliver overlay multicast groups end to end; this mechanism addresses another problem.

Fabric overlay multicast support and replication design have specific control and data-plane requirements beyond simple underlay multicast reachability. “Select a supported SD-Access multicast forwarding model and test receivers across fabric edges and virtual networks” would remedy that alternative situation, but it would not correct the present issue: a single endpoint map/control-plane service is a common-mode availability risk even with redundant data-plane links.

“Integrate the fabric with appropriate Cisco ISE identity policy and validated endpoint profiling or authentication flows” is the supported response when identity group classification requires a trusted policy source and onboarding process rather than arbitrary address-based role guessing. Here the decisive response is “Design supported control-plane node redundancy and test endpoint registration continuity during node loss”, so that different intervention does not meet the stated requirement.

IP-prefix ACLs become brittle when identity and endpoint groups move, while fabric policy can use scalable group-based classification. “Use authorized scalable group tags and matching group-based access policy integrated with the intended identity service” applies to that other condition. The reported evidence is a campus fabric has one control-plane node that maintains all endpoint registrations, and a planned node upgrade makes roaming users unreachable; this alternative would address the wrong dependency.

IBGP typically preserves the external next hop, which must be reachable through the internal routing infrastructure. “Provide appropriate next-hop-self policy or valid internal reachability for external BGP next hops with loop-free forwarding” would remedy that alternative situation, but it would not correct the present issue: local preference is not exported between autonomous systems, so changing it cannot directly govern external networks' inbound selection.

“Introduce redundant route reflectors with appropriate client hierarchy and loop-prevention identifiers” is the supported response when conventional iBGP full mesh grows quadratically and becomes costly to configure, observe and recover. Here the decisive response is “Apply approved outbound AS-path prepending on the less-preferred transit and check provider acceptance and alternate routing”, so that different intervention does not meet the stated requirement.

Internal OSPF cost does not communicate an intended interconnect preference to the neighboring autonomous system. “Use supported BGP MED where appropriate, coordinate the provider's comparison behavior and keep resilient alternate exits” applies to that other condition. The reported evidence is a multihomed public service wants remote networks to prefer one upstream for inbound traffic but changes only its own local preference; this alternative would address the wrong dependency.

That change concerns qos classification encrypted traffic, where Encryption hides much application payload from intermediate classifiers, so deep packet inspection may not see per-app content inside the tunnel. The reported issue instead stems from: Trusting unvalidated endpoint DSCP markings allows unauthorized traffic to consume preferential network resources.

That change concerns qos policing versus buffering behavior, where Policing enforces a rate by dropping or remarking excess packets, whereas shaping ordinarily smooths outbound bursts using buffers. In this question the necessary remedy is “Define an appropriate trust boundary and classify or remark traffic at access based on authenticated application and endpoint context”, which this alternative does not provide.

That change concerns diffserv versus intserv service model, where Per-flow IntServ state scales differently from aggregated DiffServ classes and can become operationally expensive for large multi-site deployments. The observed condition is a user-controlled workstation marks all outbound bulk backup packets as expedited forwarding, causing voice queues to saturate during office hours; this mechanism addresses another problem.