# An on-call engineer who responds to twenty pages a week treats the twenty-first as routine, which is Canonical URL: Domain: Pipeline Design ยท Difficulty: medium ## Problem An on-call engineer who responds to twenty pages a week treats the twenty-first as routine, which is exactly when the page that mattered slips through. The section's three severity tiers: page (PagerDuty wakeup, customer-facing SLA missed, action required within the hour), Slack channel (notification watched during business hours, daily DAG failed will retry, action waits), and email digest (weekly drift, nobody opens until something is wrong). The page-worthy test: requires action within the hour AND cannot wait for business hours AND on-call can fix it. Route the alert by adding three destinations off the monitor pipeline, one per tier, with each tech matching its tier. ## Related - [All practice problems](https://datadriven.io/problems) - [Mock interview mode](https://datadriven.io/interview/an-on-call-engineer-who-responds-to-twenty-pages-a-week-trea-d6ab8705) - [System Design Interview Questions](https://datadriven.io/data-engineering-system-design) - [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep) - [Daily Challenge](https://datadriven.io/daily) --- Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.