Software Development and Design

350-901 · 60 questions

• A city parking portal’s browser UI must show DNA Center wireless health and Meraki SSID status. Where should the integration store platform API tokens and issue those privileged controller calls?
• A municipal operations portal fans request traffic across several identical back-end workers that talk to Cisco controllers. What is the primary job of the load balancer in that design?
• A transit-authority portal stores each clerk’s session only as files on one back-end worker’s local disk while a load balancer can send the next request to any instance. What design change restores free fan-out?
• A county IT portal must show device inventory plus health views from two different Cisco controller families. How should the privileged API sessions be arranged?
• A city’s load balancer still sprays parking-portal traffic at back-end workers that fail a liveness probe and return gateway errors. Which distribution behavior should the design use instead?
• A single VM that polls Meraki sites and transforms JSON for a water-utility dashboard is CPU-saturated. The workers are designed to be identical and stateless behind a load balancer. Which scaling direction matches that constraint?
• A parks-department module both renders HTML and embeds raw UCS and DNA Center API calls in the same unit. What modularity change lets the UI and the controller hop evolve on different clocks?
• A city’s “common Cisco helper” still ships inside every portal release as a versioned library. The team wants that hop to scale and fail without rebuilding the UI. Which modularity choice matches that goal?
• Five identical workers for a civic inventory sync all append to the same local file on a shared mount and capacity stops growing linearly. What is the scalability fix?
• A library-network team runs twenty copies of one deployable that absorbs Meraki load, yet every SSID-enable change still requires rebuilding the inventory UI. What does that design still lack?
• A hybrid city ops app must keep Webex ChatOps usable when the on-premises controller is unreachable, and keep inventory usable when a SaaS Cisco API is down. What HA design property does that require?
• A 911-support portal’s recovery-time objective requires the back-end to resume serving within seconds of a worker failure, and sessions are already shared or stateless. Which HA pattern best matches that requirement?
• A utilities dashboard runs its Cisco-API worker “in the cloud” with one token file, one region, and no degraded path when that hop fails. What does that design still lack?
• A city NOC dashboard consumes Meraki and DNA Center data. Meraki returns 5xx while DNA Center is healthy. Which design response is appropriate?
• A metro IT team must survive loss of an entire data center for its Cisco-API workers, while controllers stay on-premises. Which pattern matches protecting against site loss versus only overflowing stateless workers to cloud?
• A permits portal waits for controller A, then controller B, then a local store before painting the page, and the sum of those round-trips blows the latency budget. Which design change best cuts that latency?
• A worker that polls every Meraki site every second exhausts the published controller quota and starves sibling civic apps. What design move should be chosen before implementation?
• An eight-second UCS inventory sync on the user’s click path blows a city portal’s interactive latency objective. How should that slow Cisco-API work be placed?
• Many clerks opening the same health page would each trigger the same expensive DNA Center query. Which consumer design protects latency and the platform quota?
• A civic inventory table with thousands of rows issues one REST call per row to a Cisco platform API, and the page feels slow even though each call is fast. What latency design change should be preferred?
• Five modules in a municipal portal each hard-code a DNA Center hostname, API version, and a pasted JSON body. A controller move becomes a scavenger hunt. What maintainability fix should the design use?
• A two-thousand-line grab-bag module talks to Webex, Firepower FDM, and a spreadsheet for a city helpdesk app. What structure improves maintainability?
• A permits service cannot be exercised without a live Meraki controller, so every change is expensive. Which maintainability property should the design add?
• A civic Wi-Fi portal still ships idle Meraki location-API calls “in case we need them later,” and every release must understand and patch that surface. What maintainability action fits?
• Operators cannot tell which Cisco platform hop failed for a given city-portal request because the app only emits local print statements. What observability design set should the integration hop expose?
• A city’s network team ships a portal that enables guest SSIDs through a wireless controller API. When an enable fails at 09:14, support must match the same failure on the portal error screen, the portal back-end log, and the outbound controller request log. Which design choice best enables that cross-hop match?
• A parks department app polls Meraki for AP inventory and then parses the JSON locally. Operators need to know whether Meraki is slow or the parser is. Which observability design best answers that question?
• A civic ops dashboard shows a green check because the wireless-health microservice process is listening on its port. Users still see blank charts because the controller returns empty wireless-health payloads. What should the design expose so operators see the real problem?
• A city telemetry service adds a Prometheus label for every client MAC and also stores raw Meraki response bodies inside distributed traces. After a week the metrics store is huge and traces contain PII. What observability design mistake does this illustrate?
• A library Wi-Fi enable request produces this short event log: back-end accepted req-8821; controller-A returned 200; controller-B returned 429; UI showed a generic failure. Where should diagnosis focus first?
• An automation job calls a retrieve-data API for switch inventory. One failure shows a connect-timeout with errno in the client log; another shows HTTP 400 with a body complaining about a bad template field. How should these be classified for next action?
• After a failed SSID change, the portal UI log says 10:00:01, the back-end says 09:59:40, and the controller syslog says 10:02:12, with no shared request id. Why is a “who failed first” story from these lines unreliable?
• A Python worker crashes with JSONDecodeError on an empty body while syncing Firepower FDM objects. Earlier in the same request log, a proxy hop returned 502 and the upstream call completed with 204. What is the sound diagnostic move?
• A ChatOps bot posts room messages through the Webex API. Every thirty seconds the client log shows the identical HTTP 401 Unauthorized, with no intermittent 5xx. What does that regularity most strongly indicate?
• A municipal asset registry must keep device rows consistent with site and owner tables, enforce foreign keys, and support ad-hoc joins under transactions. Which database type best fits that stated need?
• An integration caches full UCS and Intersight compute inventory documents that differ by product family and are almost always read as whole objects after each API revision. Which store type is the best fit?
• Operators ask: which applications and sites share this Catalyst Center controller, and what else fails if that node is removed? The dominant access pattern is walking relationships. Which database type best matches?
• A weekly capacity report must aggregate a few fields across millions of historical interface samples. Point lookups of whole device documents are rare. Which database layout best fits the report?
• The city NOC stores interface counters and hop latency keyed by metric name, timestamp, and device, mostly appending samples and running windowed queries. Which database type is the appropriate choice?
• Inventory must support constrained joins for current device-to-site ownership, while thirty days of poll samples need append-and-window queries. Access patterns fight inside one engine. What is the honest evaluation using only the official database-type families?
• One developer maintains a small tool that enables a single guest SSID and appends an audit line. There is one release train and no independent scale need. Which architectural pattern is justified?
• Architects compare a coarser shared-integration design to independently deployable, narrowly scoped units with decentralized data. In official DEVCOR terms, what distinction are they drawing?
• DNA Center (Catalyst Center) emits a network event that must reach a ticket opener, a ChatOps Webex notifier, and a metrics recorder. The producer must not wait on or know those consumers. Which pattern fits?
• Five containers are labeled microservices, yet they share one database and must always ship on the same release train because any schema change breaks all five. What have the architects actually built?
• Constraints: the ChatOps Webex notifier must scale and release independently from the inventory UI; one small team owns a separate batch reporter with a single weekly change window. Which pairing of official patterns best matches?
• A finished feature branch that adds Meraki SSID helpers should join the shared development line while keeping both histories visible. Which official Git operation is the correct way to combine the branch?
• During merge of a platform-client branch, Git stops because both sides edited the same function. Conflict markers appear in the file. What is the correct resolution path if the intent is to finish the merge?
• A developer made two local commits on a feature branch that have not been pushed. They want the branch pointer moved back and the index updated accordingly. Which official Git tool matches that local rewrite?
• On this blueprint, which Git operation is named for switching the worktree onto another branch or restoring a file path from a revision?
• A bad commit that broke Ansible inventory parsing is already on the shared main branch and teammates have fetched it. How should the team undo that change safely?
• A city parking-meter integration engineer experiments with a local Git commit that was never pushed. Overnight they realize the experiment should not stay in history. Separately, a shared branch already has a bad commit that three other civic apps have pulled. Which actions match those two situations?
• During a merge conflict in the city's Meraki SSID helper repo, an engineer decides the entire conflicting file from the incoming branch is correct. Which resolution completes the merge cleanly?
• The municipal transit team wants to hand operations a rebuildable DNA Center health exporter for the weekend change window. Which statement best describes a proper release package?
• The night before a library Wi-Fi automation change window, a city build pulls a new major of a shared HTTP client because dependencies floated on latest. Which practice would have kept the build reproducible?
• Two defects hit the parks-department automation packages. Package A fails on a clean runner because a required library was never listed. Package B lists two libraries that cannot be installed together. How should those packaging defects be classified?
• The water utility releases a new meter-reading app that talks to Intersight. Two engineers ship builds with different unofficial and official client library versions because the SDK was left unpinned. What should the release process treat the platform client library as?
• A civic design review asks for a sequence diagram of enabling a library-branch SSID through the city's back-end and the Meraki Dashboard API. What must the diagram show to satisfy that request?
• The city clerk's portal waits for a DNA Center wireless-health REST response before rendering. On the sequence diagram, which notation best shows that blocking synchronous call?
• A sequence diagram for the city's Webex ChatOps bot shows only the happy-path 200 from the Webex API. Design review asks how the diagram should also cover a 401 or timeout without turning into application source code. What belongs on the diagram?
• A draft sequence for the city's protected Intersight inventory pull shows the resource GET before any token acquisition hop. What is wrong with that diagram from a Domain 1 sequence perspective?