Google just introduced another security level to set custom domain for blogspot.com. Besides normal ghs.google.com to be added to the CNAME record in domain, user needs to add another 2nd unique CNAME record.
You can get the 2nd CNAME by following below steps
1. Go to blogger setting for any blog
Settings > Basic
2. Under “Publishing”, click on “Add a custom domain”
3. Click “Switch to advanced settings”
4. Enter your registered domain name
5. Click “settings instructions”
6. Choose type of domain to install.
e.g. “On a top-level domain (www.example.com).”
7. Get the CNAME under “CNAME” subject
Add two CNAME records. For the first CNAME, where it says Name, Label or Host enter “qprm” and where it says Destination, Target or Points To enter “ghs.google.com” . For the second CNAME, enter “OKQFRCLFFBSL” as the Name and “gv-MK4QLTUM3XARQLGY4ZBLD6ZMRAERAEF72BQBZAZMNN26JVOAZ6AH.domainverify.googlehosted.com.” as the Destination. See our detailed instructions on providing CNAMEs for various registrars. If yours isn’t listed, or if you run into
other difficulties, contact your registrar directly and they can help you out.