As I was working with a customer on designing their SharePoint 2010 farm using HNSC approach customer was curious on why they are not being able to return results for those site collections.
After reviewing the search service application in their POC environment and checking crawl log I noticed the following warning:
“This URL is part of a host header SharePoint deployment and the search application is not configured to crawl individual host header sites. This will be crawled as a part of the host header Web application if configured as a start address.”
After adding the URL for HNSC web application host and a crawl results started showing up and hence a happy customer …
or you can create a site collection at the root, and then it will also work without having to add the HNSCs to the content source