heroku recognizes 'myapp.com' but not 'www.myapp.com'

Just like it says in the title, I followed heroku's instructions and added 'myapp.com' and 'www.myapp.com' as domains for my heroku app.

The former works correctly but the latter does not. Any ideas? EDIT: When I point my browser to 'www.myapp.com', I get an error from Comcast, my ISP, saying that the URL was no开发者_高级运维t found.

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You can do this 2 different ways:

First way:

1. In your heroku custom domains add www.myapp.com.
2. In your DNS point the www CNAME to proxy.heroku.com

Second way:

1. Have you subdomain redirect to myapp.com

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You followed the part about DNS setup and setting up a CNAME for www.myapp.com? If so and you just set it up, it can take as many as 48 hours for all the DNS servers to update.

If that's not the case, make sure you have your CNAME record set up correctly with the domain's host so it knows about the www subdomain.