Incident Overview
You are on-call for a mid-sized e-commerce platform. At 14:00 UTC, users report intermittent failures when accessing the checkout service.
The monitoring dashboard shows two conflicting alerts: Alert A: High latency (2000ms+) from the primary recursive resolver (Resolver-1). Alert B: NXDOMAIN responses for valid subdomains from the secondary recursive resolver (Resolver-2).
The application team claims the DNS records have not changed in weeks. The network team reports no packet loss between resolvers and authoritative servers.
Investigation Options
Review the available operational moves and select the best immediate action.
A
Restart authoritative nameservers
B
Flush cache on Resolver-1
C
Restore UDP connectivity for Resolver-2
D
Set TTL to zero