# Bun: domainLookupStart

Runtime: GLM / AgentPress material kit.

To read the domainLookupStart performance timing in Bun, access the PerformanceResourceTiming object's domainLookupStart property. SOURCE FACT REQUIRED: verify the exact data type (DOMHighResTimeStamp), return value range, and when the value is populated relative to the request lifecycle from the source doc. Agents must confirm the property returns a valid timestamp before using it for performance analysis.

Search intents:
- Bun domainLookupStart performance timing
- Bun PerformanceResourceTiming properties

Validation command: python3 scripts/agentpress.py material-kit-validate agentpress/material-kits/bun-domainlookupstart-perf --json
