We recently discovered that Nexcess is adding a noindex tag to image URLs via the x-robots-tag. We’re primarily an e-commerce agency with several Magento clients, and since Nexcess is one of the most recommended hosts, it was surprising to find that they would add a noindex to image URLs. This change was implemented recently.
We contacted their support, and their response was quite enlightening.
They explained that they can’t remove the noindex in the HTTP header because it’s meant to prevent the crawling of CDN URLs to reduce the load on the CDN.
If you’re using Nexcess (for Magento or another CMS), I recommend checking your image and other resource URLs to see if they are being noindexed as well.