AceEngine

In a perfect world, name based virtual hosting would work fine and, in most cases, it gets the job done ok — not great, but ok. We’ve studied all the major search engines and each of them appear to be compliant with the HTTP1.1 protocol.
The major search engine’s write-ups are correct most of the time. However, on occasion something goes wrong, either at the ISP level or with the SE spider. In any case, the search engine ends up indexing the wrong web page. This goes to show that there is more going on than simply name based recognition of a site. By having a transitional period in which the site sits on the new server, where the DNS are pointing, and the site also sits on the original server possible ISP level or SE spider issues are alleviated.


Back in July of 1999 John Heard (highly respected search engine expert) found that Excite doesn’t like indexing different domains that have the same IP address, and existing websites in there database used content from the original IP address when a site changed IP addresses.


HTTP1.1, which is required to get name based virtual hosting to work, requires specific headers in the GET request — specially the HTTP_HOST and the REQUEST_URI variables. If that information is missing, then the web server gets mixed up (no pun intended) and often will return the wrong page — in most cases the “default” domain for that particular server.