What Is a CNAME Record?

What Is a CNAME Record?

A CNAME (Canonical Name) record is a DNS record that creates an alias, pointing one domain name to another domain name. CNAME records enable domain aliasing, allowing multiple domain names to resolve to the same destination.

CNAME records point to canonical (official) domain names, which then resolve to IP addresses via A or AAAA records. CNAME records are useful for: subdomain aliasing (www.example.com → example.com), service aliasing (mail.example.com → mail.provider.com), and domain redirection.

CNAME records cannot coexist with other record types (A, MX, etc.) at the same name. Check CNAME records to verify DNS aliasing and domain redirection. Learn more about DNS.

CNAME Record Purpose

Domain Aliasing

CNAME records create aliases, allowing multiple domain names to point to the same canonical domain name.

Subdomain Management

CNAME records enable easy subdomain management by pointing subdomains to canonical domain names.

Service Redirection

CNAME records redirect service subdomains (mail, www, ftp) to provider services or canonical domains.

Domain Simplification

CNAME records simplify DNS management by centralizing IP address management at canonical domains.

Flexibility

CNAME records provide flexibility in domain management, allowing easy changes to canonical domains.

CNAME vs A Record

CNAME records and A records serve different purposes:

A Records

• Map domain names directly to IP addresses
• Final resolution (no further DNS lookup needed)
• Can coexist with other record types
• Used for root domains and direct IP mapping

CNAME Records

• Map domain names to other domain names (aliases)
• Requires additional DNS lookup to resolve canonical name
• Cannot coexist with other record types at same name
• Used for subdomains and aliasing

When to Use Each

Use A records for root domains and direct IP mapping. Use CNAME records for subdomains and aliasing.

CNAME Record Uses

1. WWW Subdomain

Common use: www.example.com CNAME example.com - Points www subdomain to root domain.

2. Service Aliasing

Service aliasing: mail.example.com CNAME mail.provider.com - Points mail subdomain to provider service.

3. CDN Integration

CDN integration: cdn.example.com CNAME cdn.provider.com - Points CDN subdomain to provider CDN.

4. Domain Redirection

Domain redirection: old-domain.com CNAME new-domain.com - Redirects old domain to new domain.

5. Load Balancing

Load balancing: Multiple CNAME records can point to different canonical names for load distribution.

Checking CNAME Records

1. DNS Lookup Tools

Use DNS lookup tools to query CNAME records and retrieve alias information for domains.

2. Command Line Tools

Use command-line tools (dig, nslookup) to query CNAME records: dig CNAME www.example.com

3. Domain Health Check

Use our domain health check to verify DNS configuration including CNAME records.

4. Verification

Verify CNAME records point to valid canonical domain names, canonical names resolve correctly, and CNAME records don't conflict with other record types.

5. Resolution Testing

Test DNS resolution to verify CNAME records resolve correctly to canonical names and ultimately to IP addresses.