Many developers face a common DNS challenge when trying to set up CNAME records at the root domain level (also known as the apex or naked domain). While this appears to be a convenient solution for managing multiple domains pointing to the same IP, it technically violates RFC 1912 and RFC 1034.

The fundamental issue stems from how DNS resolution works at the zone apex. When you create a CNAME at the root:

example.com. IN CNAME otherdomain.com.

This creates conflicts with other essential records that MUST exist at the same level, particularly:

• SOA (Start of Authority) records
• NS (Name Server) records
• MX (Mail Exchange) records

Some providers like 1and1 implement non-compliant solutions that appear to work:

; DIG output showing non-compliant CNAME at apex
example.com.      71605   IN   CNAME   target.com.
target.com.      59      IN   A       192.0.2.1

This violates RFC standards because:

1. It prevents proper NS record resolution
2. Breaks DNSSEC validation
3. Causes issues with email delivery (MX records)

Instead of root CNAMEs, consider these alternatives:

1. ALIAS/ANAME Records (Provider-Specific)

Many modern DNS providers offer special record types:

; Cloudflare ALIAS example
example.com. IN ALIAS target.com.

2. Using a Subdomain

The simplest compliant solution:

www.example.com. IN CNAME target.com.

3. DNS Redirect Services

Services like AWS Route 53 offer:

; Route 53 S3/CloudFront redirection
example.com. IN A 192.0.2.1
(With website redirection configured)

For AWS Route 53 users:

{
  "Comment": "Root domain redirect to www",
  "Changes": [{
    "Action": "UPSERT",
    "ResourceRecordSet": {
      "Name": "example.com",
      "Type": "A",
      "AliasTarget": {
        "HostedZoneId": "Z2FDTNDATAQYW2",
        "DNSName": "s3-website-us-east-1.amazonaws.com.",
        "EvaluateTargetHealth": false
      }
    }
  }]
}

Always verify your setup with:

dig example.com +nostats +nocomments +nocmd
dig www.example.com +nostats +nocomments +nocmd
dig MX example.com +short

---

When you try to set up a CNAME record at your root domain (e.g., example.com instead of sub.example.com), most DNS providers like DynDNS will block this operation. This isn't arbitrary - it violates RFC 1912 section 2.4 which clearly states:

"A CNAME record is not allowed to coexist with any other data"

At the root level, your domain must have SOA and NS records, making a CNAME impossible under RFC rules. The 1and1 example you found is technically non-compliant, even if it "works".

Three technical reasons explain the blockade:

• Nameserver Resolution: When resolving example.com, the first lookup checks NS records. A CNAME would redirect before finding these critical records.
• Mail Delivery: MX records can't coexist with CNAMEs at root level.
• DNSSEC Validation: Cryptographic verification breaks with illegal CNAME configurations.

For your goal of maintaining a single IP reference, consider these RFC-compliant solutions:

// Option 1: ALIAS/ANAME Records (DNS provider specific)
example.com.  3600  IN  ALIAS  target.example.net.

// Option 2: Multiple A Records
example.com.  300  IN  A  192.0.2.1
www.example.com.  300  IN  CNAME  example.com.

// Option 3: Reverse Proxy Setup (Nginx example)
server {
    listen 80;
    server_name example.com www.example.com;
    location / {
        proxy_pass http://[your-ip]:8080;
    }
}

Some DNS providers offer special record types that mimic root CNAMEs while maintaining RFC compliance:

Provider	Record Type	Behavior
Cloudflare	CNAME Flattening	Resolves to A record automatically
AWS Route 53	Alias Record	Points to ELB/CloudFront directly
DNSimple	ALIAS	On-the-fly resolution

To verify your existing setup, use these diagnostic commands:

# Check all record types
dig example.com ANY +noall +answer

# Trace delegation path
dig example.com +trace

# Test specific record types
dig example.com MX
dig example.com NS

Remember that non-compliant configurations like 1and1's implementation may break unexpectedly during DNS protocol updates or security audits.