[1] When used in the computer security lexicon, "Footprinting" generally refers to one of the pre-attack phases; tasks performed before executing the actual attack.
That is the reason by which it may be named a Pre-Attack, since all the information is reviewed in order to get a complete and successful resolution of the attack.
Active Footprinting is the process of using tools and techniques, such as performing a ping sweep or using the traceroute command, to gather information on a target.
Active Footprinting can trigger a target's Intrusion Detection System (IDS) and may be logged, and thus requires a level of stealth to successfully do.
WHOIS[6] is a web application used to get information about the target website, such as the administrator's e-mail address and details about the registration.
Information can also be gathered using the command Tracert ("traceroute"), which is used to trace a path between a user and the target system on the networks.