I was trying to map a custom domain name to site I have created in Google App Engine. However, the custom domain is not getting applied to the site. Below are the steps that I have performed after checking Google Help Sites and stackoverflow answers.
1. Created / Uploaded Google App Engine Site
http://myGoogleSite.appspot.com/
2. Purchased a domain name
mydomain.com
3. Created a CNAME Record with my domain name provider
Name: www
Value: ghs.google.com
4. Created a Google apps account
https://www.google.com/a/mydomain.com
5. Verified domain name in Google apps account
6. Enabled services for Google App Engine.
Added site http://myGoogleSite.appspot.com/ (Created in Step 1)
7. Google Admin Panel
Settings > Select Google App Engine site
Added New Web Address
RESOLVED
The issue has been resolved without any other changes after a day. I think the CNAME entry which I had added in domain name server did get applied a day later. Though I had checked it through dnsstuff.com on the same day and they were reflected correctly.
If the CNAME www does not work when directed to ghs.google.com, try ghs.googlehosted.com instead. It's what at least some of their docs say.
For a company that can pretty accurately sift through millions of pages for related data, their documentation on their own products sucks hard.
The issue has been resolved without any other changes after a day. I think the CNAME entry which I had added in domain name server did get applied a day later. Though I had checked it through dnsstuff.com on the same day and they were reflected correctly
来源：https://stackoverflow.com/questions/11280542/google-app-engine-custom-domain