You may want to add landing page CNAMEs to allow different URLs to point to your Marketo landing pages. Following the steps below will help you manage multiple domains.
Cookies are not shareable across domains.
Same top level domain - Good! Cookies are shared.
go.mycompany.com > info.mycompany.com
Different top level domains - Bad! Cookies are not shared.
go.mycompany.com > go.mynewcompany.com
Admin Permissions Required
Go to the Admin area and click Landing Pages.
Copy the Account String from the Settings section.
Make a note of it for the next step.
Ask your IT department to setup the following CNAME: (Replace the word [CNAME] with the CNAME of your choice and [ACCOUNT STRING] with the text from the previous step).
[CNAME].YourCompany.com > [ACCOUNT STRING].mktoweb.com
Once your IT department has created the CNAME, go to Admin then click Landing Pages.
Click New then select New Domain Alias.
Enter your Domain Alias. The Default Page is displayed if the visitor does not put in a URL. Enter where they should go in that case.
For the Default Page, you can select a landing page or an external URL, such as your public website.
Enter your Default Page and click Create.
Nice! Now you know what to do if you ever want to add a CNAME.