You must prepare content for search engines or your site will never rise above the clutter of the hundreds of millions of Web pages each major search engine holds in its index. If the IP is from a search engine, the server feeds a highly-optimized page. Otherwise it delivers a regular page such as the Home page. IP cloaking is also known as IP spoofing or IP delivery. IP cloaking is often abusive in how it attempts to manipulate a search engine's index.
Some practitioners develop hundreds of IP-cloaked pages using software.
Since IP cloaking hides content, pages optimized around irrelevant key phrases are often developed. Consequently search engines routinely purge IP cloaked pages, and in some cases, ban these sites from their indexes. That depends on who you talk to. Some search engine marketing firms simply add meta-tags to a page and call it a Doorway page. Those using IP cloaking develop their own kind of Doorway pages.