The Flash Sale That Blocked 40% of Paying Mobile Shoppers
The Flash Sale That Blocked 40% of Paying Mobile Shoppers
Your luxury sneaker marketplace hosts high-heat limited drops where 50,000 pairs sell out in 90 seconds. Scalper botnets running distributed checkout scripts flood the site with 120,000 requests/second. To prevent bots from wiping out stock, the infrastructure team places Cloudflare Turnstile managed challenges on the /checkout/place-order endpoint, configured with aggressive security thresholds. During the Saturday drop, the bot attack is successfully blunted, but customer support is inundated with thousands of furious paying customers: over 40% of legitimate human mobile shoppers were unable to complete their purchases. Mobile shoppers on cellular networks (T-Mobile/Verizon) share Carrier-Grade NAT (CGNAT) gateway IP addresses with thousands of other cellular devices, causing Turnstile's IP reputation scoring to classify them as suspicious automated clusters. Furthermore, mobile in-app browsers (WebViews) and users with strict privacy settings or Safari Private Browsing failed the interactive cryptographic challenge, trapping human shoppers in infinite challenge loops while inventory sold out. You are tasked with architecting a robust managed challenge integration that mitigates bot automation while protecting mobile carrier users and high-value checkout conversion.
The Flash Sale That Blocked 40% of Paying Mobile Shoppers
Your luxury sneaker marketplace hosts high-heat limited drops where 50,000 pairs sell out in 90 seconds. Scalper botnets running distributed checkout scripts flood the site with 120,000 requests/second. To prevent bots from wiping out stock, the infrastructure team places Cloudflare Turnstile managed challenges on the /checkout/place-order endpoint, configured with aggressive security thresholds. During the Saturday drop, the bot attack is successfully blunted, but customer support is inundated with thousands of furious paying customers: over 40% of legitimate human mobile shoppers were unable to complete their purchases. Mobile shoppers on cellular networks (T-Mobile/Verizon) share Carrier-Grade NAT (CGNAT) gateway IP addresses with thousands of other cellular devices, causing Turnstile's IP reputation scoring to classify them as suspicious automated clusters. Furthermore, mobile in-app browsers (WebViews) and users with strict privacy settings or Safari Private Browsing failed the interactive cryptographic challenge, trapping human shoppers in infinite challenge loops while inventory sold out. You are tasked with architecting a robust managed challenge integration that mitigates bot automation while protecting mobile carrier users and high-value checkout conversion.
Provide 1–2 precise sentences for each architectural dimension. Each box guides you on what staff-level interviewers evaluate.
Define SLA targets, hard consistency constraints, and conditions the system must never violate.
Quantify throughput (QPS/RPS), read:write ratios, and peak burst multipliers.
Step-by-step path: client ingress → API gateway → queues → background workers → persistence.
Database engine, table schema, partition keys (PK/SK), and durability strategy.
What resource hits saturation first under 10x traffic? (CPU, disk IOPS, connection pools, network).
Worker crashes, network partitions, split-brain, poison pill DLQ, retries, and idempotency.
What did you sacrifice in exchange and why? (e.g. eventual consistency vs latency, cost vs redundancy).