There are many different sources that are helpful when deciding whether an IP address belongs to a datacenter or not.

But the following steps are essential and most relevant:

  1. Self published IP ranges from hosting providers need to be considered
  2. The downloadable whois databases from RIR’s such as RIPE-NCC or ARIN can be searched.
  3. Manual task: A list of datacenters and hosting providers needs to be compiled. With this list of datacenter needles, the whois databases from the RIR’s can be searched/grepped.