Over the Air iOS Adhoc Build using Relative URL

With HTTP or HTTPS requests, a relative URL can be processed by the web browser to fill in the missing details. The link to the .plist file is a custom URL scheme. Safari doesn't know the format of the URL, so it doesn't fill in any missing details. So that link must be an absolute URL. Safari just looks for something that can handle a itms-services URL scheme, and sends off the whole URL to that scheme.

The link to the .ipa file also must be absolute, not because the program that handles the itms-services URL scheme doesn't have enough information, but because that program doesn't run the logic built in to process the URLs. I'm guessing that Apple prefers to keep that code simple and reliable rather than add the relative URL feature.

One solution you have is to write some sort of server side processor of your HTML and PLIST files to produce rewritten files with absolute URLs based on the server. How you chose to get this done will depend upon the configuration of your servers.

Another solution is to keep the .plist and .ipa on the main webserver, use absolute URLs to that server, and work with your HTML file on both servers.