Trying to simplify something here. We have an ad that's used by multiple sources so I would like to use one LP. If I redirect many URLs to the one Master do I have a record of the referring URL? This would help me know the source so I could write the lead to the appropriate list.
I know there are other ways to do this but I'd like to keep the URL parameter free if possible.
I'd recommend using the original page URL and tag it with UTM. Very intuitive with Marketo. This is the best practice.
I am afraid you will have to test it with a clean browser to know if it works
I am also afraid you would loose many referrers, though, so I would rather use a URL shortener, but a good one. See Sanford's recommendation here: Re: Can you hide UTM parameters in URLs using Link Shorteners?
You wouldn't lose any referrers per se, which is actually the reason you won't see the original URL to which the user navigated.
The original referrer remains in place on a 301 redirect. So the Master page will see the referrer that brought you to the Alias (2 hops away, if you will).
There's no way to feed information to the Master page unless the Alias appends info before redirecting. If you use a URL param (which Robb doesn't want to) it will be appended. Otherwise, in the absence of a server programming language, you could have an LP that acts as a redirector, using a JS redirect (document.location) and appending the Alias URL.