we change our main LP domain to solutions.widget.com and change current main LP domain to be an alias - solutions.acme.com
New Setup:
LP domain = solutions.widget.com
Alias = solutions.acme.com
Alias in place so older LP still work (per another comment you replied to in community)
New Marketo LPs now solutions.widget.com
Scenario:
someone fills out form on new LP or embedded form (either solutions.widget.com or embedded form on either www.acme.com or www.widget.com) so now identified and part of our Marketo database. We assume that if they then visit pages on widget.com they will be tracked per normal but if they visit pages on acme.com will they be tracked.
Cookies are never accessible across private suffixes.
Consider a cookie set on the page solutions.example.com/mypage.html.
Option A: The cookie may be set for the full current domain (solutions.example.com). In this case, all other pages under solutions.example.com can read and write it, but neither (a) pages at the parent example.com nor (b) pages under another subdomain of example.com like blog.example.com nor (c) pages under any other domain on the internet can access the cookie.
Option B: The cookie may be set for the shortest private suffix, which is example.com. In this case, all other pages under solutions.example.com can read and write it. In addition, pages directly under example.com, like example.com/aboutus.html, and pages under any other subdomain of example.com, like blog.example.com/trishsblog.html can access the cookie. However, pages under any other private domain on in the internet, like another.example.info or yetanother.example.test cannot access the cookie.
There's no Option C: You can't make a cookie set at or under example.com accessible at or under example.info. You can only manipulate which levels under example.com can access it, you can't break out into someone else's domain (even if your company happens to have purchased both domains, from a browser security standpoint this doesn't matter, they are never taken as a single domain).
So if someone fills out a form at or under example.com, that same cookie will be visible and associated with the same lead at solutions.example.com (or vice versa) if you use Option B above. (Munchkin attempts to use Option B by default.)
But on another.example.info there (a) is no cookie at all until they visit there and (b) the cookie that's created when they first visit will be anonymous, until separate action is taken to associate it.
and what happens if existing known people (from when LP domain was solutions.acme.com now go to pages on www.acme.com will they still be tracked or will that be broken due to LP domain change.
Existing associated cookies will remain associated.
Marketo does not care if you have 10 different associated cookies under 10 different domain suffixes. Every activity in each of those Munchkin sessions will be tracked. But there's no communication between domains, each one must be separately associated.
For us the overall issue is: if we change main LP domain to solutions.widget.com from solutions.acme.com what will happen in terms of tracking with previously known people (when main LP domain was solutions.acme.com) and what will happen in terms of tracking for net new people (when main LP domain is now solutions.widget.com)
If a person has an associated cookie on solutions.example.com that cookie remains in the browser.* But it's only used on example.com.
On or under example.info, the cookie simply does not exist. So the person will start out with a new, anonymous cookie. If you can get them to click a tracked link to solutions.example.info or fill out a form on www.example.info, then that new cookie will be associated. Until then, if they just happen to be redirected to solutions.example.info when browsing the web, they'll be anonymous on example.info.
we are basically trying to use our Marketo instance to still use www.acme.com as our main site and to embed forms on for another 6 months-1 year before total transition to www.widget.com. is this even possible?
Of course, it's completely possible, but you can't magically have people who were known on Domain A be known on Domain B. If you can get an associated cookie on both domains, they'll both be tracked.
* until the browser removes it due to inactivity, which is defined differently based on browser vendor, or it expires
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