$ curl -I https://registry-1.docker.io/v2/
HTTP/1.1 401 Unauthorized
content-type: application/json
docker-distribution-api-version: registry/2.0
www-authenticate: Bearer realm="https://auth.docker.io/token",service="registry.docker.io"
date: Sat, 28 Jan 2023 01:39:06 GMT
content-length: 87
strict-transport-security: max-age=31536000