CNAME setup for new users? I followed the examples on the landing page but it won't accept anything I try.

David,

Please see
http://www.marketingrockstarguides.com/dkim-spf-and-cname-setup-for-marketo-289/

or 

http://www.slideshare.net/jdavidhill/marketo-administration-instructions

Have you setup your CNAME/subdomain on your DNS? You need to do that first.

This is very helpful.  Thank you.  I got the landing page setup but the Fallback page is still a problem.  I would have thought the same procedure would be accepted there too but it is not.  I used lp for the landing page and go for the Fallback page.  Marketo seems to be looking for something different because it won't accept the fallback page.

Marketo likes me better this morning because now it accepted the very same thing.

I think the issue was that I needed to give GoDaddy time to put the DNS changes into the system.

Hi David,
that's possible. DNS changes take up to 24 hours.

Best regards

Steffen