What caused the sudden 30% increase in latency for Flare's DNS resolution service last week?

Introduction

The sudden 30% increase in latency for Flare's DNS resolution service last week is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll follow a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our service.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this could be related to a recent deployment. Has there been any significant update or change to the DNS resolution service in the past week?

Why it matters: Recent changes often correlate with performance issues. Expected answer: Yes, there was a deployment on Tuesday. Impact on approach: If confirmed, we'd focus on changes in that deployment.

• Considering the scale of the issue, I'm wondering about the geographic distribution. Is this latency increase uniform across all regions, or are some areas more affected than others?

Why it matters: Helps identify if it's a global issue or localized to specific data centers. Expected answer: The issue is more pronounced in certain regions. Impact on approach: We'd prioritize investigating those specific regions and their infrastructure.

• Given the nature of DNS services, I'm curious about traffic patterns. Have we seen any unusual spikes in DNS query volume coinciding with the latency increase?

Why it matters: Unusual traffic patterns could indicate DDoS attacks or misconfigurations. Expected answer: Traffic volume has remained relatively stable. Impact on approach: If true, we'd focus more on internal system issues rather than external factors.

• Thinking about potential hardware issues, I'd like to know if there have been any recent changes or issues with our server infrastructure or network equipment.

Why it matters: Hardware problems can significantly impact service performance. Expected answer: No major hardware changes, but there was a network switch upgrade in one data center. Impact on approach: We'd investigate the impact of the network upgrade on DNS resolution performance.