domain without www not working, but with www is working on Azure

we have a site that we recently moved to Azure, did the DNS mapping for www.sitename.com and also for sitename.com however when I access the site without any www prefix, it throws up an error. when I provide www. prefix it works fine.

what could I be missing ?

How do I point my domain without www?

Without the 'www', you must set your root (non-www) domain DNS A-record to point at your web server's IP address. This can be too rigid if you encounter availability or performance issues; the A-record is fixed and can take a day or two for changes to propagate.

How do I point my domain to Azure?

Sign in to the Azure portal using a Global administrator account for the directory. Search for and select Azure Active Directory from any page, then select Custom domain names. In Custom domain names, select the custom domain name.

Within Azure go to Domain Mappings and make an entry for sitename.com in addition to www.sitename.com ! that worked for me.. I remember trying to do that earlier, but Azure did not allow the entry without a www. originally (about a month back) but now it accepted and started working immediately.