Reselling web hosting services is a very common thing. Your own web hosting provider may be a reseller without you even knowing it! Reseller hosts typically pay for a more expensive account with another host, and have tools to re-sell you space out of their allottment.
There is a slight difference between reselling and co-locating which is outlined in a future post.
So how do you check if your host is a reseller? It can be tricky, but the first place to check is this website: http://www.whoishostingthis.com. Enter your web hosts domain (ie: hostgator.com). It will run what’s called a “reverse DNS lookup” which will indicate where the servers are actually located. At one time Hostgator was actually hosted by a company called “The Planet” which is a large-scale server leasing company. The company has since changed hands and is now hosted on their own servers.
Another thing to look out for is when you use a CDN, or “content delivery network.” CDNs cache a site’s content that is served on your primary host server and use a system of distributed servers to speed up delivery of that content to users around the world. Cloudflare is a popular example of a CDN. For example, one of our sister sites, globalwarmingisreal.com, is served at Pair Networks, one of the hosts on our Top 10 list of green hosting providers. But since the site uses Cloudflare for content distribution, services such as whoishostingthis.com sees Cloudflare as the hosting provider, instead of Pair, the primary host.
Reseller hosting is not necessarily a bad thing. If you are looking for basic hosting services, this is a perfectly fine source. If you want core access, root access, and very specific requirements, you may want to look at companies who are not resellers.