Can't set "example.com" as a CNAME record?

You cannot set a CNAME record for a root domain (e.g., example.com) because that would break RFC 1034 section 3.6.2, which states,

If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different.

You can’t do this for example.com because example.com will also have NS records to make it work which breaks the rule that no other data should be present.

You can have a CNAME record for www.example.com because this is not the root domain, and therefore it is easy to have no other data present for it.

The only ways to get around this are to either

• use the www prefix, or
• to get your domain parked where you want the CNAME record to point, and get the relevant IP address to set up an A record for example.com.

I just read that you’re using dynamic DNS. Some dynamic DNS providers can work with your domain if you host it on their nameservers: this way their dynamic DNS updaters can update example.com’s IP address, and you avoid any CNAME issues altogether. Off the top of my head I only know of dyndns offering this as a paid service.

You can not set naked domain name in CNAME records. You must have to do ONLY those settings for alias domains like www.example.com , about.example.com and more at CNAME records and the primary or ROOT domain settings must be done at A Records and you have to provide IP address of host. First delete the settings from CNAME about the naked domain and set it at "A Records" and then do settings at C Name for alias like www, about or anything like that.

This may help you: A Records, CNAME, MX Records : Basics to Setup Your Blog

I found that CNAME of a naked domain via @ Record like mentioned here doesn't work for some domain providers. To get out from this you can consider to point your NAME SERVERS to a DNS provider who support the ALIAS or ANAME.

Follow to this there are some DNS hosts provide a way to get CNAME-like functionality at the zone apex (the root domain level, for the naked domain name) using a custom record type.

Such records include, for example:

• ALIAS at DNSimple
• ANAME at DNS Made Easy
• ANAME at easyDNS
• CNAME at CloudFlare
• ALIAS at CloudDNS

For each provider, the setup is similar: point the ALIAS or ANAME entry for your apex domain to example.yourdomain.com, just as you would with a CNAME record.

ALIAS or ANAME or @ example.whateverdomain.com.