Serverless notebook DNS failure (gai error / name resolution)

[bek04]

I’m using a Databricks workspace on AWS (region: us-west-2). My Serverless notebook (CPU) cannot access any external URL — every outbound request fails at DNS resolution.

Minimal test in a notebook:
import urllib.request
urllib.request.urlopen("https://www.google.com/robots.txt", timeout=20)

Errors I get:
- URLError: <urlopen error [Errno -3] Temporary failure in name resolution>
- gaierror: [Errno -2] Name or service not known

Notes:
- SQL Warehouse works normally.
- Unity Catalog is enabled and I’m using Volumes (/Volumes/...).
- I already attached/updated the Network Connectivity Configuration (ncc_public_internet), but the notebook still has DNS failures.

What should I check next (network policy / serverless egress control / workspace setting) to enable outbound internet/DNS for Serverless notebooks?