System designMediumsd-g579

Subject System designLevel Mid–Senior~40 minCommon in Reliability & on-call interviewsIndustries IT services, Technology

Question

Design a support-ticket routing + SLA-tracking system for an IT helpdesk handling ~40K tickets/day across ~800 agents in multiple regions/skills. Requirements: route incoming tickets to the right agent queue by skill/priority/region, track SLA timers (first-response and resolution targets that vary by priority and pause during business-hours-off / customer-waiting states), escalate or alert when an SLA is about to breach, and rebalance load when an agent goes offline. Read-heavy dashboards but timer correctness is critical.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.