---
title: "2025-09-20 - DNS Resolution Failure in analytics-pipeline"
date: 2025-09-20
severity: P1
services: [analytics-pipeline, notification-service]
tags: [rca, p1, network]
status: resolved
duration_minutes: 22
author: Infrastructure
---
# 2025-09-20 - DNS Resolution Failure in analytics-pipeline
## Summary
On 2025-09-20, the analytics-pipeline service experienced a dns resolution failure. The incident lasted approximately 22 minutes and affected 2701 users and 2 dependent services.
## Timeline
| Time (UTC) | Event |
|------------|-------|
| 16:40 | Monitoring alert triggered |
| 16:42 | On-call engineer paged |
| 16:45 | Initial investigation started |
| 16:50 | Root cause identified |
| 16:53 | Mitigation applied |
| 16:57 | Service recovery observed |
| 17:02 | Incident resolved |
## Root Cause
The incident was caused by dns resolution failure in the analytics-pipeline service.
Investigation revealed multiple contributing factors:
1. Recent code changes introduced a regression
2. Test coverage did not include edge cases
3. Monitoring gaps delayed detection
## Impact
- Service degradation: 61% of requests affected
- Error rate spike: 19% (baseline: <1%)
- Latency increase: p99 went from 222ms to 4464ms
### Affected Services
- analytics-pipeline
- notification-service
### Customer Impact
- 3209 customer-facing errors
- 14 support tickets created
- Estimated revenue impact: $36285
## Resolution
1. Deployed hotfix to address the immediate issue
2. Added regression tests for the affected code path
3. Implemented additional monitoring and alerting
4. Updated runbook with troubleshooting steps
## Lessons Learned
### What Went Well
- Alert fired within 4 minutes of incident start
- On-call response was quick (5 minutes)
- Cross-team collaboration was effective
- Communication to stakeholders was timely
### What Could Be Improved
- Need better runbooks for network issues
- Monitoring coverage gaps identified
- Load testing should cover this scenario
- Need automated rollback for faster recovery
## Action Items
| Priority | Action | Owner | Due Date |
|----------|--------|-------|----------|
| P1 | Implement monitoring for dns resolution failure | SRE | 2025-09-27 |
| P2 | Update runbook | SRE | 2025-10-04 |
| P2 | Add load test scenario | Infrastructure | 2025-10-11 |
| P3 | Review similar services | DevOps | 2025-10-20 |
## Related Incidents
- [[2025-09-20-previous-incident|Previous network incident]]
- [[runbook-analytics-pipeline|analytics-pipeline Runbook]]
- [[architecture-network|Network Architecture]]
---
*RCA prepared by Infrastructure on 2025-09-22*
